The chronic periodontitis in patients with acute coronary syndromes. The in ammation link between periodontal disease and coronary atherosclerosis


 Background

Coronary atherosclerosis and periodontal disease, due to their prevalence, are a serious epidemiological problem. Pathophysiological evidence points to their possible common inflammatory etiopathological background. The aim of the study was to analyze the relationship between the presence and severity of periodontitis, systemic inflammation and selected parameters of myocardial injury and heart function in patients with acute myocardial infarction.
Methods

The study group consisted of 71 patients 54.22(7.05) - year - old hospitalized due to acute myocardial infarction. The patients underwent a coronary angiographic examination and echocardiography. The following laboratory parameters were determined: blood morphology, hsCRP, ESR, fibrinogen, troponin I, CK-MB, BNP, lipidogram, glucose, creatinine, GFR, TSH, HbA1c. Dental assessment of the patients was performed and the following indicators were included: the number of teeth preserved, approximal plaque index (API), bleeding on probing (BoP), pocket depth (PD), the number of bleeding periodontal pockets ≥ 4 mm in depth (NoPD ≥ 4 mm), the percentage of bleeding periodontal pockets ≥ 4 mm in depth (%PD ≥ 4 mm), clinical attachment loss (CAL). The severity of periodontal disease and periodontological treatment needs were determined using the Community Periodontal Index of Treatment Needs (CPITN).
Results

The BI (bleeding index) significantly correlated with fibrynogen. All indices regarding the pocket depth (PD, NoPD ≥ 4 mm,% PD4 ≥ mm) correlated significantly with the number of leukocytes. PD and NoPD ≥ 4 mm were also associated significantly with the level of hsCRP. The BI is correlated closely with the levels of BNP. The multifactorial analysis showed that significant predictors of myocardial infarction are API and BI. The analysis showed that API and BI are important predictors of troponin levels. Linear regression analysis showed that only CAL is a significant predictor of BNP.
Conclusions

Patients with acute myocardial infarction have worse periodontal status in the AAP and CPITN classification compared to people without coronary heart disease. Higher severity of periodontal disease, poorer oral hygiene and increased activity of the periodontitis leads to greater manifestation of systemic inflammation in patients with acute myocardial infarction. Periodontitis is a risk factor for myocardial infarction and also affects the degree of post-infarction left ventricular damage, which means that there is an inflammatory link between these two diseases.


Introduction
Due to their prevalence, cardiovascular diseases are considered as social diseases; they are also among the most common causes of death worldwide [1]. Periodontal diseases, in turn, belong to the most common illnesses of the oral cavity and, along dental caries, constitute the main cause of teeth loss. Periodontal infections are also linked to the risk pattern of several systemic diseases such as cardiovascular diseases or rheumatoid arthritis [2]. The data, concerning oral hygiene behaviour and cardiovascular risk associated with oral health status, for the research was obtained from the National Health Insurance System-National Health Screening Cohort (NHISHEALS), and included 247,696 participants free from any history of cardiovascular diseases. The participants were recruited in the years 2002 and 2003 and all reported the initial presence of periodontitis resulting in a greater teeth loss.
Consequently, this was associated with an increased risk of major cardiovascular events (MACEs) in the future such as cardiovascular death, acute myocardial infarction, heart failure, and stroke [3]. The common factors contributing to the incidence of both cardiovascular disease and chronic periodontal disease include ageing, smoking, alcohol abuse, race/ethnicity, education and socioeconomic status, male sex, diabetes mellitus, and overweight or obesity [4,5]. Scienti c evidence also indicates the presence of genetic factors in periodontitis and cardiovascular diseases [6].
Due to personal hygiene neglect, bacterial colonize the cervical regions of the teeth, forming dentogingival bacterial plaque, known as bio lm, which constitutes a kind of an ecological niche, protecting them from antiseptics and antibiotics. The most common periodontal illness is in ammation of those tissues resulting from a bacterial infection. It leads to migration of epithelium forming a gingival pocket towards the root, destruction of collagen bres of the periodontal ligament, and also to bone resorption within the alveolar process [7,8]. Periodontitis is preceded by gingival in ammation (gingivitis), which is reversible if a proper therapy is employed. As a result of in ammation of the periodontium, tissues surrounding the tooth are in ltrated by neutrophils, macrophages and, subsequently, by activated lymphocytes, releasing, e.g., interleukin-1, prostaglandin E 2 , and tumour necrosis factor-α [9]. A considerably large area of the periodontal tissue, as well as its dense vascularisation, enables bacteria, bacterial metabolic products, and in ammatory mediators to enter the bloodstream and thus promotes endothelial dysfunction [10].
It has been known for a while that periodontitis alone is an independent risk factor contributing to the development of atherosclerotic vascular disease and the underlying mechanism is systemic in ammation [4]. Atherosclerosis is a chronic in ammatory process affecting the intima of mainly large and medium caliber arteries, leading to formation of lipid build-ups created as a result of accumulation of in ammatory cells and the formation of a bro-lipid structure, referred to as atherosclerotic plaque.
Theories regarding the pathogenesis of atherosclerosis have changed over time. Currently, the role of autoimmune and in ammatory conditions in the onset and progression of atherosclerosis and in developing its complications is underlined. Endothelial dysfunction resulting from immune and in ammatory reactions within the vessel wall is the earliest and most important process in the development of atherosclerosis [11,12].
Coronary artery disease, connected to atherosclerotic in ammation, and acute coronary syndromes are conditions resulting in the increase of both C Reactive Protein (CRP) levels and leukocytosis [13]. Leukocytes take part in atherosclerosis through their participation in the in ammatory process; they cause endothelial dysfunction, microcirculation disorders, have proteolytic, oxidative, and procoagulant effect.
The mechanisms with which active in ammatory lesions in the periodontal tissue in uence the blood vessel wall are still in the scope of numerous researches. The immune and in ammatory background of those dependencies is emphasized. Among a few complementary hypotheses, there are two most important ones; the rst one stipulates that bacteria and their toxins have a direct impact on the vessel wall during bacteremia; the second one assumes that cytokines and in ammatory mediators released during chronic periodontal in ammation may potentially affect the vessel wall. [14,15]. In clinical practice, however, important, and from a practical point of view more useful in assessing the degree of in ammation of the periodontal tissues are methods for the visual assessment of advancement of periodontosis [16,17]. Determining the severity of the disease is based on assessing the clinical position of the attachment (CAL) and the pocked depth (PD), whereas the activity of the in ammatory process is assessed on the basis of the presence of bleeding on probing (BoP) [18]. Despite many data supports the relationship between periodontitis and atherosclerosis, which are two common civilization pathologies, still too little attention is paid to the search for their joint etiopathogenesis to limit their adverse social effects.

Aim Of Study
The main goal was to analyze the relationship between the presence and severity of periodontitis and selected parameters of myocardial injury and heart function in patients with acute myocardial infarction. In addition, the impact of periodontitis on selected laboratory and morphological parameters of in ammation was analyzed in patients with acute myocardial infarction and in the group of people without con rmed ischemic heart disease.

Materials And Methods
coronary heart disease. The outpatient clinic performed 64-slice multidetector computed tomography ambulatory examinations to determine the status of coronary heart disease. Based on these examinations, only patients without changes in coronary arteries were included in the control group. They were also subjected to periodontal examination.
All the patients were interviewed for factors of ischemic heart disease such as: nicotinism, hypertension, diabetes, and lipid disorders. Patients were measured for height and weight and their body mass index (BMI) was determined; BMI in the range 25-29.9 kg/m² was de ned as overweight and ≥ 30 kg/m² as obesity.

Cardiology assessment
In the study group, the patients underwent a standard coronary angiographic examination on an Innova 4100 angiograph (GE Healthcare, Waukesha, WI) [19]. After the evaluation of coronary arteries, patients underwent revascularization in accordance with current standards [20]. Echocardiographic tests were performed with a Philips iE33 (Koninklijke Philips Electronics NV) in accordance with the principles of the American Echocardiographic Society, assessing the following echocardiographic parameters: left ventricle enddiastolic diameter, left ventricle endsystolic diameter, left ventricle ejection fraction (by the Simpson method), left atrium maximal diameter, right ventricle enddiastolic diameter [21].
Blood counts were determined by ow cytometry using an ADVIA 2120i apparatus (Siemens); brinogen level by measuring the clotting time using the ACL TOT 500 apparatus of the Instrumentation Laboratory.
The lipid pro le was determined by the enzymatic method, HDL-cholesterol level by direct elimination with catalase, TG level by spectrophotometric enzymatic reaction, CRP level by the immunoturbidimetric method using latex, HbA 1C by the immunoturbidimetry method, glucose level by the hexokinase method, creatinine by the Jaffe method with alkaline picrate. These tests were performed with the ADVIA 1800 apparatus from Siemens. BNP and TSH levels were determined by direct chemiluminescence using the ADVIA Centaur XP apparatus from Siemens. TnI in whole blood was determined by electrochemiluminescence using a Roche Elecsys 2010 analyzer (Roche Diagnostics GmbH, Mannheim, Germany). The minimum detection level was 0.01 µg/l.

Dental examination
Dental assessment of the patients was performed on the bedside on the next day after the admission to the Department of Cardiology. In order to ensure the uniformity and repeatability of the assessment, an oral examination was performed by one dentist. Dental examination was performed with the use of arti cial lighting, with a dental mirror and a Hu-Friedy PCPUNC 15 perio probe. Third molars were excluded from the examination. Patients enrolled in the study had to have at least 6 teeth. The following indicators were included in periodontal assessment: -the number of teeth preserved, -approximal plaque index (API) by Lange [16], -bleeding on probing (BoP) by Ainamo and Bay [17], -bleeding index (BI) was calculated (the number of points where bleeding was present was divided by the entire number of examined sites and multiplied by 100), -pocket depth (PD), which was measured from the edge of the gum to the bottom of the pocket found by probing, -the number of bleeding periodontal pockets ≥ 4 mm in depth (NoPD ≥ 4 mm), -the percentage of bleeding periodontal pockets ≥ 4 mm in depth (%PD ≥ 4 mm), -clinical attachment loss (CAL), which is de ned as the distance from the bottom of the pocket identi ed during probing and the enamel-cement border.
The parameters were assessed at four points: mesiobuccal, buccal, distobuccal, and lingual.
The severity of periodontal disease and periodontological treatment needs was determined using the Community Periodontal Index (CPI) of Treatment Needs (CPITN) [22], with the following groups: -CPI-0 -no in ammatory symptoms, -CPI-1-bleeding on probing, -CPI-2-presence of supragingival and/or subgingival stone, -CPI-3 -occurrence of pathological periodontal pockets with a depth of 3.5 to 5.5 mm, -CPI-4-occurrence of pathological periodontal pockets with a depth of 5.5 mm and above Periodontitis has also been categorized according to the American Academy of Periodontology (AAP) classi cation [23] for: -healthy periodontum, -gingivitis, -slight chronic periodontitis, -moderate chronic periodontitis, -severe chronic periodontitis, -aggressive periodontitis

Statistical analysis
The obtained data were analysed with the use of Microsoft O ce 2007 and StatSoft Statistica v. 10.0. In the statistical description of the obtained results, the average, median, minimum, and maximum values were used. Normal distribution of data was tested with the Shapiro-Wilk test, while homogeneity of variance was estimated with the Levene's test. To compare the control and study groups, Mann Whitney's U analysis was performed. The concentrations of the studied parameters were tested with the Univariate Analysis of Variance (ANOVA); the post-hoc analysis was performed with the use of Tukey's honest signi cant difference test (HSD). In the case of a lack of homogeneity of variance, Kruskal-Wallis's nonparametric test was used. The correlation between the parameters was described with Spearman's rank correlation coe cient.
Logistic regression analysis was performed to determine the prediction model of myocardial infarction.
To determine the prediction of troponin, BNP and EF levels, linear regression analysis was performed. The in ation variance coe cient was assessed for all parameters included in the linear regression analysis. Thus, the value of this coe cient allowed to determine whether a given predictor was correlated with other predictors in the model. The lack of collinearity of predictors in the model was assumed in cases when the coe cient reached the value of ≤ 4, and the parameter was included in the analysis. However, when the value of the coe cient was ≥ 5, it indicated the possibility of collinearity between the predictors, consequently the parameter was excluded from the analysis. The ROC analysis was applied to assess the quality of the classi cation of the occurrence or the lack of occurrence of a myocardial infarction .
Moreover, the differences found were considered statistically signi cant at the p level < 0.05.

Basic characteristics
The study group consisted of 71 people hospitalized due to myocardial infarction. The average age in the study group was 54 (from 36 to 65 years of age). The clinical characteristics of the study group are shown in Table 1. On the basis of the markers of myocardial necrosis in serum samples (TnI, CK, CK-MB, and myoglobin) and electrocardiography, according to the accepted standards, non-ST-elevation myocardial infarction was recognized in 30% of the patients, while ST elevation myocardial infarction in 70%. The patients underwent coronary angiography. In coronary angiography, 39% of patients had signi cant coronary stenosis in one coronary artery, while 61% of patients had a multivessel disease. Hemodynamically signi cant atherosclerotic plaques were described in 3% of cases in the left main coronary artery, in 75% of patients in the left anterior descending artery, in 51% in the circum ex artery and 48% of patients in the right coronary artery (61% of patients had stenosis in more than one vessel).
The majority of the patients (97%) were subjected to an invasive treatment, i.e. percutaneous coronary intervention (n-66) or coronary artery bypass grafting (n-3). The remaining patients were provided with conservative treatment (n-2). Comparison of CPITN percentages in the study and control group with the chi square test (X 2 ) showed a statistically signi cant difference between the control and study group in the numerical values of the CPITN groups, with the chi-square test value (X 2 = 20.47), the number of degrees of freedom (df = 4) and probability p = 0.0004. The absence of in ammatory symptoms (CPITN 0) was extremely rare in both the study and the control group. Minimal in ammatory changes (CPITN 1) were observed signi cantly more often in the control group, while advanced periodontal pockets with a depth of 5.5 mm and above (CPITN 4) dominated in the study group (Fig. 1).
Annotation: Community Periodontal Index (CPI) of Treatment Needs (CPITN), CPI-0 -no in ammatory symptoms, CPI-1-bleeding when probing, CPI-2-presence of supragingival and/or subgingival stone, CPI-3 -occurrence of pathological periodontal pockets with a depth of 3.5 to 5.5 mm, CPI-4-occurrence of pathological periodontal pockets with a depth of 5.5 mm and above The most common form of periodontitis, according to the AAP classi cation, also more often observed in the study group than in the control group was advanced chronic periodontitis. Other degrees of in ammation were less common and did not differ statistically compared to the control group (Fig. 2).

Periodontological indices and in ammatory biochemical markers
An analysis of the relationship between periodontological indices and in ammatory biomarkers showed that most of the evaluated indices were signi cantly associated with hsCRP and leukocytes levels. The BI was statistically signi cantly associated with the level of brinogen in the study group. All indices regarding the pocket depth (PD, NoPD ≥ 4 mm, %PD ≥ 4 mm) correlated signi cantly with the number of leukocytes. PD and NoPD ≥ 4 mm were also associated signi cantly with the level of hsCRP. There was also a statistically signi cant relationship between CAL and hsCRP levels in the study group. However, the number of teeth preserved was associated with ESR (Table 2).

Periodontal indices and markers of heart injury and function
Analysis of the relationship of periodontological indices with biochemical markers of heart injury and function showed few signi cant correlations. It has been shown that the BI is correlated closely with the levels of BNP in both the study group. The other analyzed periodontological parameters did not correlate with parameters of myocardial injury and function (Table 3).

Multifactorial analysis
A multifactorial analysis was performed in order to determine whether the analyzed periodontological indices are independently related to the myocardial infarction occurrence and markers of heart injury and function.

Model of prediction of myocardial infarction
In order to determine the model explaining the probability of occurrence of myocardial infarction, logistic regression analysis was performed using the backward elimination method, taking into account the likelihood ratio, where the explained variable was the occurrence of myocardial infarction, and predictors: number of teeth, API, BI, PD, CAL and CPITN. The Hosmer Lemeshow test turned out to be irrelevant, which indicates a good t of the model to the data. Important predictors of myocardial infarction are API and BI (Table 4). With an increase in API by 1%, the probability of having a heart attack increases by 8% (OR = 1.08), while with a 1% increase in BI, the probability of having a heart attack decreases by 7% (OR = 0.93). Annotation: B -non-standardized regression coe cient; SE -standard error; Wald -Wald test value; OR -odds ratio; 95%CI -con dence interval; p -signi cance level.
The ROC analysis was used to show the performance of the proposed model of prediction of myocardial infarction. The ROC analysis was applied to assess the quality of the classi cation of the occurrence or the lack of occurrence of a myocardial infarction based on the following three variables: API, BI and PD. Figure 3 illustrates the ROC curves, while Table 5 summarizes the results of the analysis.  The next step focused on establishing a model explaining the BNP level. For this purpose, linear regression analysis using backward elimination was used. Model includes the number of teeth, API, BI,

PD, NoPD ≥ 4 mm, CAL and CPITN as predictors. Linear regression analysis by backward elimination
showed that only CAL is a signi cant predictor ( Table 7). As the CAL increases by one unit, the BNP value increases by 31.33 units.

Discussion
The main assumption of the thesis that periodontitis affects the initiation and progression of atherosclerosis is the fact that the periodontal disease cause subtle systemic in ammation. The present study has revealed elevated levels of in ammation markers in the study group. Leukocytes count was Moreover, CRP contributes to the production of foam cells, formation of reactive oxygen species and to the proliferation and migration of smooth muscle cells [24]. The systematic review and meta-analysis of the study on the correlation between periodontitis and CRP levels conducted by Paraskevas et al. [25] demonstrated elevated CRP levels in blood serum of patients with periodontitis in comparison to healthy people. It was also shown that, among patients with stable coronary artery disease, elevated CRP level increases the risk of myocardial infarction, while in patients with myocardial infarction, it contributes to an increased risk of complications and worse prognosis [26,27,28]. A multicentre Stability Study showed a link between in ammation markers like hsCRP and interleukin-6 and periodontitis. In this study a large number of patients were collected, however, unlike the present study, the simplest indicator of periodontal disease, which is a tooth loss, was used [29]. In present study, hsCRP level correlated with the parameters attesting to the advancement of the periodontal disease, such as: PD (R = 0.28; p = 0.01), NoPD ≥ 4 mm (R = 0.24; p = 0.04); moreover, there was a positive correlation with the clinical attachment loss CAL (R = 0.27; p = 0.02). Different results were obtained by Górski et al., who did not demonstrate any correlation between CRP levels and periodontal markers [30]. However, Swaroop et al. [31], demonstrated in their study statistically signi cantly higher levels of in ammation markers, such as hsCRP and brinogen, among people with chronic periodontitis than among those with the healthy periodontium (p < 0.001); what is more, they proved positive correlations between hsCRP levels and brinogen and the measured periodontal parameters (PD, BI, CAL).
Another extremely important result of the present study is the relationship between periodontal disease and brinogen. Namely, a positive correlation between the values of the BI marker, indicating active in ammation of periodontium, with the level of brinogen (R = 0.36; p = 0.006). Fibrinogen is a protein synthesized by hepatocytes and broblasts in response to in ammation. The level of brinogen in the blood correlates with the severity of atherosclerotic lesions, the risk of an acute coronary syndrome, and mortality among patients with myocardial infarction. Fibrinogen participates in the thrombotic process; it is also pro-in ammatory, as it increases the expression of adhesion molecules and stimulates production of in ammatory mediators by endothelial cells [28,32]. This has an additional signi cance in the studied group of patients with acute myocardial infarction, where prothrombotic hyperactivity is a key pathogenetic factor. The study by Bokhari et al. [33], in which 317 patients with coronary artery disease and periodontitis were examined, indicated correlation between BI and the level of brinogen. Also Górski et al. [30] documented positive correlation between the concentration of brinogen and the values of BI (p = 0.0587), as well as between the number of lost teeth and the level of brinogen (p = 0.0003). Seringec et al. [34], in turn, demonstrated considerably higher levels of hsCRP, brinogen, and globulins among patients with chronic periodontitis, as well as a higher tendency of erythrocytes to aggregate than in people with healthy periodontium.
The present study has demonstrated correlation between the leukocytes count and the parameters indicating the severity of the periodontal disease, such as PD (R = 0.27; p = 0.02), NoPD ≥ 4 mm (R = 0.28; p = 0.02), as well as %PD ≥ 4 mm (R = 0.28; p = 0.01). Numerous epidemiological studies showed positive correlation between leukocytes count and the risk of coronary artery disease. In a prospective NHAHES I epidemiological study, a group of people with the leukocytes count < 6600 cells/mm³ was compared with a group with the leukocytes count > 8100 cells/mm³; it was found that increased leukocytes count is linked to an increased risk of coronary artery disease among white males (RR = 1.31; 95% CL 1.07-1.61) and white females (RR = 1.31; 1.05-1.63) aged 45-74, taking into account other cardiovascular risk factors [35]. In the meta-analysis of seven most important studies regarding the correlation between the leukocytes count and coronary artery disease, which encompassed 5,337 participants with ischemic heart disease, the difference between the leukocytes count below or equal to 2800 cells/mm³ was connected to the total RR of 1.4 [36].
Bearing in mind the main purpose of the research, indicating the correlation between periodontical markers and myocardial injury and heart failure indicators was the most important. Univariate analysis has been demonstrated a signi cant relationship between BI and the level of BNP in the study group (R = 0.29; p = 0.02). Linear regression analysis using backward elimination showed that a signi cant predictor of BNP is only CAL. As the CAL increases by one unit, the BNP value increases by 31.33 units. For the left ventricle ejection fraction prediction, none of the analyzed models were statistically signi cant (F < 1.62; p > 0.210) and none of the analyzed variables were a signi cant predictor of left ventricle ejection fraction (p > 0.05). BNP is recognized as a prognostic marker in patients with acute coronary syndromes. It is believed that BNP inhibits the growth of cardiomyocytes and broblasts, impairs collagen synthesis in relation not only to the myocardium but also to periodontal tissues [37]. The increase in BNP is in uenced by factors such as smoking, stress, diabetes, and age [38]. These are also risk factors for periodontal disease. Increased serum BNP levels are observed in patient with periodontitis compared to those without periodontitis. Studies by Leira et al. have shown that increased destruction of periodontal correlates with a higher serum BNP level [39]. On the other hand, in patients with coexisting heart failure and periodontidis professional periodontal treatment can contribute to a decrease in the values of BNP [40].
As a potential mechanism linking periodontal disease with heart failure, cross-reactivity between periodontal and myocardial antigens mediated by chronic Toll-like receptor activation is suspected [41]. Current results seem to con rm the thesis that periodontitis is associated with the biochemical features of heart failure in the course of myocardial infarction. It probably depends on the size of heart injury, as it was asserted by Mar l-Alvarez. This author indicated the correlation between periodontitis and the size of myocardial infarction. This observation is re ected by the higher level of troponin and myoglobin depending on the extent of the myocardial injury [42]. This observation in patients with myocardial infarction is extremely important from a prognostic point of view. Perhaps, an unfavorable prognostic factor in patients with myocardial infarction is not only classic and well-established BNP level but also periodontitis. However, this requires validation studies dedicated to this issue. showed that the TnI concentration was positively associated with indicators of the extent and severity of chronic periodontitis. Interestingly, the relationship between chronic periodontitis severity and TnI was mediated by the total leukocytes count. On the contrary, current results for patients with acute myocardial infarction are quite different from the data presented by Vedin et al. [29]. Indeed, they found no relationship between periodontal disease, which a simple index was the loss of teeth, and the level of troponin. It should be noticed, however that this study focused on patients with stable coronary heart disease. In earlier studies these authors showed no relationship between tooth loss and myocardial infarction in this population [43].
An equally important and original result of the study is the signi cant association of periodontitis with risk of myocardial infarction. The logistic regression analysis showed that API and BI are signi cant predictors of myocardial infarction. With the increase in API by 1%, the probability of myocardial infarction increases by 8% (OR = 1.08), while with a 1% increase in BI, the probability of myocardial infarction decrease by 7% (OR = 0.93). The current ndings are consistent with the results of the PAROKRANK study of 805 people [44]. A relationship has been demonstrated between moderate to severe periodontitis, objectively con rmed by radiological bone loss, and the rst myocardial infarction. Stability Study is a study dedicated to similar topics [29,43]. In contrast to the our study in PAROKRANK study showed no association with periodontal disease and the onset of the rst myocardial infarction. However, while various aspects of cardiovascular risk were assessed in this study, including myocardial infarction, all analyzes were based on a single but very simple indicator of periodontitis which is the number of teeth preserved. Since this was a multicenter observational study, the application of a general parameter that periodontal disease is justi ed. Remaining in this aspect in a sharp contrast to the present study, it also highlights its originality and methodical credibility. First, it emphasizes the comprehensiveness and diversity of periodontological data collected in the current study. Secondly, it concerns the acute phase of myocardial infarction, which the nature of the disease justi es the di culties in obtaining so many periodontological data. The fact that the increase in the BI ratio by 1% is accompanied by a reduction in the risk of heart attack by 7%, also requires comment. Of course, higher BI indicates a greater severity of periodontitis. It should be remembered, however, that during the dental examination, patients in accordance with acute coronary syndromes treatment standards were already on dual antiplatelet therapy, which undoubtedly increases the risk of bleeding [20,45]. Moreover, the severity of bleeding may be a clear evidence of the effectiveness of antiplatelet therapy, while it might be a problem in dental treatment in the period after acute coronary syndromes [46]. The explanation for this apparently unexpected relationship can therefore be seen in that -it is a net effect of the severity of periodontitis and the increased bleeding tendency associated with dual antiplatelet therapy. On the basis of the conducted analyses, it may be concluded that periodontitis is a condition which may affect the risk of the development of ischaemic heart disease as well as its complications in the form course of myocardial infarction, as it causes a mild systemic in ammatory response. Undoubtedly, social awareness of the possible clinical implication of periodontitis is insu cient. Considering the prevalence of the ischaemic heart disease, high mortality resulting from cardiovascular diseases, and the ubiquity of periodontitis in the Polish society, the periodontal health of the patients with ischemic heart disease should be taken into account and appropriate preventive and curative measures ought to be introduced. Moreover, patients with periodontitis should have their cardiovascular risk assessed. Focusing on any possible correlation between periodontal in ammation and the occurrence of ischaemic heart disease is of utmost importance due to the fact that this may be a modi able risk factor. The importance of chronic periodontitis should be taken into account in both primary and secondary prevention of cardiovascular disease [47,48]. What is more, even a single additional tooth brushing episode per day in healthy adult patients can reduce the incidence of atherosclerotic cardiovascular disease events [3]. However, the available literature does not provide su cient evidence to support or refute the potential bene t of periodontitis treatment in secondary prevention of cardiovascular disease [48,49]. Undoubtedly, further trials are necessary to conclude whether or not the periodontal disease treatment can help prevent the occurrence or recurrence of cardiovascular disease [60]. According to the recently consensus report published in 2020, patients with periodontitis should be informed about the higher risk for cardiovascular diseases, such as myocardial infarction or stroke, and as such, they should actively manage all their cardiovascular risk factors (smoking, exercise, excessive weight, blood pressure, lipid and glucose management, and su cient periodontal therapy and periodontal maintenance) [48].

Strength and Limitations
The obvious and permanent limitation of studies with extensive research methodology is a relatively small number of patients. For two reasons, the undoubted indubitable limitation is also used pharmacotherapy for two reasons. Firstly, the use of statins, which is a known anti-in ammatory agent, may modify the severity of the systemic in ammation. However, patients with acute myocardial infarction have not yet used statins in most cases, and blood samples were taken before the drug was started. In turn, antiplatelet drugs may by their nature increase bleeding, including those associated with stomalotological assessment. The more that periodontal examination was performed 24 hours after the onset of myocardial infarction and thus anti-platelet activity was fully developed. For ethical reasons, however, this restriction cannot be eliminated because it is not possible to delay the treatment of myocardial infarction for periodontal assessment. It should be emphasized, however, that both in the case of statins and antiplatelet drugs the limitation resulting from their use loses some strength due to the fact that almost all patients had the same treatment. It proves the pharmacological uniformity of the examined group, which increases the reliability of the results. Another limitation is also possible coexistence of other in ammatory processes in patients from the study group. To this end, special care was taken to exclude from the study patients who, at the time of inclusion in the physical examination or in additional examinations, had additional, beyond the periodontium, detectable foci of in ammation.
An undoubted advantage of the study is the extensive dental methodology using many periodontological indices. Both the detailed assessment of the periodontal status and the multitude of periodontal indices applied in the study can guarantee an increased reliability of statistical analysis of the obtained results.
These studies can increase the interest in the prevention and treatment of periodontal disease in order to improve both the periodontal status and the prevention of cardiovascular diseases in the population.

Conclusions
Patients with acute myocardial infarction have worse periodontal status in the AAP and CPITN classi cation compared to people without coronary heart disease.
49. Li C, Lv Z, Shi Z, Zhu Y, Wu Y, Li L, Iheozor-Ejiofor Z. Periodontal therapy for primary or secondary prevention of cardiovascular disease in people with periodontitis. Cochrane Database Syst Rev.
2019;12:CD009197. Figure 1 Comparison of the study and control group in reference to CPITN diagnoses Comparison of the study and control group according to the diagnosis of the AAP