Changing chronobiology of cardiovascular outcome following prophylaxis.

ABSTRACT

Cardiovascular events like angina, myocardial infarction and stroke have shown an increasing occurrence in the morning hours. We did this pilot nested case control study to see for any change in the time pattern of occurrence of cardiovascular events among patients on prophylaxis. A pilot study was done and the demographic characters, history of cardiovascular diseases, time of occurrence of cardiovascular event, history of drug intake and compliance were noted. Eighty four patients on prophylaxis and 135 patients presenting for the first time reported during the study period. Age did not show any significant difference. More males were getting prophylaxis for stroke and for the combined cardiovascular events. Time distribution of events showed peak occurrence between 8 to 12 hr followed by 20 to 24 hr among those who were not on prophylaxis and reverse in those on secondary prophylaxis. Odds of developing cardiovascular events though was not significantly different, was higher between 16-20 hr (1.26), 20-24 hr (1.48) and 0-4 hr (1.22) among those on prophylaxis. Seventy eight patients were taking antihypertensives. This observation demands further studies to determine the cause of evening increase in cardiovascular event especially since very little is known regarding evening exaggeration of risk factors which is becoming relevant especially in those getting prophylaxis.