Association of cardiovascular risk factors with the different presentations of acute coronary syndrome1

OBJECTIVE: to identify the relationship between different presentations of acute coronary syndrome and cardiovascular risk factors among hospitalized individuals. METHOD: cross-sectional study performed in a teaching hospital in São Paulo, in the State of São Paulo (SP). Socio-demographic, clinical and anthropometric data of 150 individuals hospitalized due to acute coronary syndrome were collected through interviews and review of clinical charts. Association between these data and the presentation of the syndrome were investigated. RESULTS: there was a predominance of ST segment elevation acute myocardial infarction. There was significant association of systemic hypertension with unstable angina and high values of low density lipoprotein with infarction, without influence from socio-demographic characteristics. CONCLUSION: arterial hypertension and high levels of low-density lipoprotein were associated with different presentations of coronary syndrome. The results can provide support for health professionals for secondary prevention programs aimed at behavioural changing.


Introduction
Cardiovascular diseases (CVD) are the main causes of morbidity and mortality in Brazil and worldwide (1) and constitute a serious public health issue. In Brazil, between January and October 2012, circulatory diseases represented 20.6% of all deaths, 24% affecting adults between 20 and 59 years old, in the prime of their productive years. Death from acute myocardial infarction (AMI) represented 12.1% in this group (2) .
Among the non-modifiable risk factors for the development of CVD, age over 55 years old, a family history of CVD, male sex, and ethnicity for certain conditions can be mentioned. Some of the modifiable risk factors are dyslipidemia (DLP), smoking, systemic arterial hypertension, physical inactivity, obesity, diabetes mellitus (DM), unhealthy diet and psychosocial stress. Dyslipidemia is the main predictor of CVD, mainly due to the high serum concentrations of low density lipoproteins (LDL) (3) .
Excessive LDL levels in the circulation contribute to the formation of atheromatous plaques in the arterial endothelium, whose presence in the coronary artery progressively reduces the vessel's lumen, restricting blood flow and possibly leading to Acute Coronary Syndrome (ACS) (4) . The signs and symptoms of ACS constitute a continuum of intensity, from unstable angina (UA) to non-ST segment elevation myocardial infarction (NSTEMI) and ST segment elevation myocardial infarction (STEMI). Unstable angina and NSTEMI result from a coronary artery partially or intermittently occluded by the formation of thrombus on the plaque, whereas STEMI is the result of a coronary artery totally occluded by a thrombus (4) .
The importance of controlling modifiable factors, such as hyperrtension, DM and DLP is reinforced by the Brazilian Society of Cardiology Guidelines, which also emphasize their role of independent markers for a worse prognosis among individuals with UA and NSTEMI (5)(6) .
Prevention is understood as a basic pillar in the reduction of morbidity and comorbidity rates, and must be prioritized for individuals who present with risk factors for the development of ACS (7) .
In order for preventive measures to be undertaken, investigation of individual characterization according to the different presentations of ACS is necessary, because these presentations are associated with distinct outcomes in hospitalization. Percutaneous coronary intervention (PCI) is more frequent among patients with AMI than among those with UA, and coronary artery bypass grafting is more frequently performed in patients with UA (8) . Thereby, the different prevalence of risk factors in the individuals may influence the presentations of ACS and, as a consequence, patients' clinical outcome.
Recent studies have investigated factors related to ACS according to its clinical manifestation in patients hospitalized following the first episode (8)(9)   The classification of individuals according to the glycemia results was based on: normal fasting blood glucose<100mg/dL; reduced glucose tolerance: fasting blood glucose >100 and <120mg/dL; DM: fasting blood glucose ≥126mg/dL (10) .
Waist-hip ratio was obtained through the division of the abdominal circumference measurement by the hip measurement. The result was assessed according to the World Health Organization (WHO) cut-off points: for men, <1 is favorable and ≥1.1 is unfavorable, and for women, <0.85 is favorable, and ≥0.85 is unfavorable (12) .
The classification for obesity was obtained

Results
The sample consisted of 150 patients. Their sociodemographic characteristics were not significantly related to the type of presentation of ACS (Table 1). Regarding the medical diagnosis, STEMI was predominant (72.7%), followed by UA (14.7%) and NSTEMI (12.7%). Table 2 shows that hypertension, DLP and DM stood out among the main comorbidities in the sample and as the most prevalent family antecedents. There was a significant association of hypertension with UA (p=0.002).
There was a greater frequency of patients among whom one or two coronary arteries (69.3%) were affected (Table 3). One coronary artery being affected was significantly associated with NSTEMI As shown in Table 4, the mean values for fasting blood glucose were above the normal limits in all the participants in the study, and the values for TotCh, LDL and TG were close to the limits considered normal or above them, whereas the mean HDL value was low. In Brunori EHFR, Lopes CT, Cavalcante AMRZ, Santos VB, Lopes JL, Barros ALBL.
relation to WHR, all the women participating were above the normal levels. The minimum WHR for the women was 0.85. Among the men, 66% had an appropriate WHR, with a minimum value of 0.78 and a maximum value of 1.38. There was a significant association between LDL values and the diagnosis of AMI (p=0.009). Rev. Latino-Am. Enfermagem 2014 July-Aug.;22(4):538-46.  thrombosis (17) .
The same study mentioned above performed in the non-metropolitan region of São Paulo verified that the length of inpatient treatment is greater among individuals admitted with UA, although the incidence of complications is greater among those who had infarction (8) . These data are relevant because they demonstrate the importance of knowing the manifestations of the different presentations of ACS, as these show varying rates of complications and mortality.
In the present study, women predominated among the individuals diagnosed with UA. It is believed that the persistence of symptoms of myocardial ischemia eventually led them to seek assistance, avoiding further progression of the disease. Compared with patients being hospitalized for the first time with a diagnosis of AMI, individuals with UA recognized at an earlier stage that they must seek professional help, as they present greater limitations for day-to-day activities in the week that precedes hospitalization due to ACS (19) . Regarding the arterial occlusion, particular attention must be given to patients with RCA occlusion, as this artery is generally responsible for the blood supply to most of the right ventricle. Mortality from right ventricle infarction is high when accompanied by lower wall infarction (25% to 30%). Thus, these patients are considered high priority for early reperfusion (6) .
The fact that PCI was the most frequently used treatment in this study's population is a reflection of the predominance of STEMI as a manifestation of coronary artery disease, with a greater proportion of occlusion of up to two coronary arteries, mainly the ADA and RCA (14) . The type of coronary artery affected is directly related to the treatment instituted. These data may also be influenced by the time of arrival of the patients with AMI in the emergency department, which should be less than 90 minutes, this limit being stipulated by the Brazilian Society of Cardiology for PCI in this diagnosis (6) . It was recently demonstrated by nurses from the non-metropolitan region of the State of São Rev. Latino-Am. Enfermagem 2014 July-Aug.;22(4):538-46.
Paulo that the arrival time of patients with infarction in a specialized emergency service varied by up to 183.3%.
The minimum time for the occurrence of the event and the attendance was nine hours 45 minutes and the maximum time was 19 hours and nine minutes (20) .
In relation to the laboratory values, the presence of mean values for glycemia above normal limits in all the participants in the study was observed. The values for TotCh, LDL and TG were close to the limits considered normal or above them, whereas the mean value for HDL was low.
Previous studies with coronary patients also found similar results to those evidenced in the samples studied regarding the presence of high levels of blood glucose, TotCh, LDL and TG and low levels of HDL (14)(15)18) .
The INTERHEART study ascertained that DLP is among the most important risk factors for the occurrence of AMI (21) . In Brazil (14) and in the metropolitan region of São Paulo (15) , the main risk factors for AMI are DM, increased WHR, a family history of coronary artery disease, increased LDL, hypertension and smoking.
In this study, the majority of the patients had high levels of blood glucose. AMI was most frequent in patients with high levels of LDL, confirming the high prevalence of insulin resistance among individuals who present coronary artery disease and ACS, as well as the important association of high levels of LDL with the diagnoses of STEMI and NSTEMI.
The higher plasma levels of LDL in the patients with AMI reflect the process of evolution of the atherosclerotic plaque in coronary artery disease (17) . The WHR also determines the individual's risk for developing CVD, as it defines the distribution of body fat. High WHR has been indicated as a predictive factor for CVD, irrespective of the BMI. Some studies show that men and women with high WHR values have a greater risk of death, syncope, ischemic myocardiopathy, glucose intolerance, and higher levels of blood pressure and serum lipids (18) .  (22) .  (22) .
In Another limitation refers to the data collection instrument used, which was not submitted for validation, although its variables were based on national guidelines for ACS. Future studies could submit the instrument for content and face validation by expert nurses.

Conclusions
The most frequent diagnosis was STEMI followed by UA and NSTEMI, with PCI being the treatment range of overweight and WHR was above normal levels.
There was a significant association of hypertension with UA and values of LDL with AMI, without influence from socio-demographic characteristics. Although