Heart rate and cardiovascular events: a nested case-control in Isfahan Cohort Study.

INTRODUCTION: Elevated heart rate (HR) is known to be a risk factor. The aim of the present study was to investigate the association of HR with the incidence of cardiovascular disease (CVD) in Iranian adults. METHODS: The Isfahan cohort study (ICS) was a longitudinal study started in 2001 on 6504 adults aged ≥ 35 years in urban and rural areas of central Iran. In a nested case control study, a control was randomly selected for each CVD event occurring during 7 years of follow up using density sampling method. HR at baseline was assessed by electrocardiogram. CVD was defined as incident coronary heart disease (myocardial infarction, unstable angina and sudden cardiac death) and stroke. The odds ratios (OR) were estimated by conditional logistic regression. RESULTS: 432 participants with CVD events in the case group and 401 participants free of CVD in the control group were included in the analysis. While HR did not show any significant relationship with CVD events in the crude model (P = 0.208), it was detrimentally associated with them when age was included (OR = 1.01, 95% CI: 1.00 - 1.02, P = 0.024). A dose response effect of quintiles of HR was seen in which significant association with CVD events started at third quintile [OR = 1.98 (1.15 - 3.41)] and increased toward fifth quintile [OR = 2.53 (1.47 - 4.36)] in the adjusted model for age, sex and HR-lowering drugs (P for trend = 0.001). This association remained statistically significant when other traditional risk factors were included in the model. CONCLUSIONS: An elevated heart rate was associated with the occurrence of cardiovascular events. It can be considered as a predictor of cardiovascular disease independently of other risk factors in Iranian adults.

Incidence of cardiovascular diseases in an Iranian population: the Isfahan Cohort Study.

INTRODUCTION: Accurate estimates of the incidence of  cardiovascular diseases (CVD) comprising of acute myocardial infarction (AMI), unstable angina pectoris (UAP), sudden cardiac death (SCD), and stroke are very important for public health. However, such information is scarce, especially for middle- and low-income countries.  METHODS: The Isfahan Cohort Study (ICS) prospectively followed up 6504 individuals, 51.8% women, aged 35 years and over, 6323 initially free of CVD, from urban and rural areas in three districts in central Iran including Isfahan, Najafabad, and Arak. A panel of specialists in cardiology and neurology decided on the diagnosis of the occurred events based on patients' hospital records, verbal autopsy, and death certificates.  RESULTS: After 32893 person-years of follow-up, 427 new cases of CVD events (229 in men) were registered. Confirmed cases of AMI, stroke, UAP, and SCD were 57, 43, 93, and 36 in men and 32, 48, 100, and 18 in women, respectively. The corresponding crude incidence rates were 352, 265, 352, and 220 per 100000 person-years in men and 186, 279, 584, and 104 in women, respectively. No significant differences were found in age at the time of events occurrence between men and women and between different event types except for SCD and stroke in women that in average the former occurred nine years later. CVD mortality rate was 331 per 100000 person-years in men and 203 in women.  CONCLUSION: We found substantially high incidence rates for almost all CVDs and mortality. These findings need urgent consideration by health policy makers specifically for women.

Appropriate cut-off values of waist circumference to predict cardiovascular outcomes: 7-year follow-up in an Iranian population.

OBJECTIVE: Due to the lack of compelling evidence for waist circumference (WC) as a cardiovascular disease (CVD) risk factor in many ethnic groups, the need for local research has been expressed by international authorities. This study was undertaken to determine the optimal cut-off points of WC for predicting incident CVD and metabolic syndrome in an Iranian population. MATERIALS AND METHODS: A total of 6,504 participants from three areas in central Iran were followed over 7 years. Receiver operating characteristics (ROC) and area under the curve (AUC) were used to identify the maximum value of sensitivity and specificity combinations corresponding to the appropriate cut-off points of WC for the detection of the metabolic syndrome and CVD events. The optimal cut-off values were defined as the point at which the value of "sensitivity+specificity-1" reached the maximum value. Finally, Cox proportional hazard modeling was used to determine which cut-off point was better fit in the CVD risk prediction model. RESULTS: After 394,418 person-years of follow-up, 427 incident primary CVD events (233 men) were identified. Considering CVD, the optimum cut-off points were 99/103.5 cm (men/women) but these had a low sensitivity (AUC: 0.59, 95%CI 0.55-0.63 in both men and women). The second highest values for discriminating CVD were 93/97 cm that resulted in acceptable sensitivity. Regarding the metabolic syndrome, 92.6/97.8 cm were identified as optimum (AUC: 0.67, 95%CI 0.65-0.69 in men and 0.65, 95%CI 0.63-0.67 in women). The best cut-off values that fit in the Cox regression model were 90/97 cm. CONCLUSION: International recommended WC cut-off values for the Middle East are not appropriate compared to the locally defined cut-off values in Iran.