Introduction :
Myocardial infarction is the most cause of heart failure. The incidence of heart failure after MI has been reported as high as 23% in various studies. Characteristics of patients in India who develop heart failure after a myocardial infarction are less well studied. Though presence of higher incidence of reduced LV function with delay in revascularization time is established, rates of reduced LV function after different modes of revascularization and correlation with coronary artery lesion is not well established.
Aim and Objectives :
To study the incidence of left ventricular dysfunction after the initial episode of myocardial infarction and to determine the difference in rates of development of LV dysfunction depending on time to perform revascularization and based on mode of revascularization and to correlate the development of LV dysfunction with the coronary artery lesion as determined by coronary angiogram.
Methodology :
93 patients admitted in PSG Hospital from 1st March 2013 to 31st December 2013 with a diagnosis of Acute ST Elevation Myocardial Infarction and undergoing reperfusion therapy with either streptokinase or by percutaneous coronary intervention were included. Window period and door to needle/door to balloon time are recorded. Left ventricular ejection fraction, as determined by volumetric method, is measured within first 24 hours and on day 5 by a single person to avoid interpersonal variation. Development of heart failure based on Framingham criteria is noted. Use of diuretics is noted. Coronary artery lesion by coronary angiogram is noted.
Results :
Out of 93 patients included in the study, 32 underwent primary PCI and 61 underwent thrombolysis. Patients with longer reperfusion time showed a significant reduction in LV ejection fraction. Patients retaining a normal ejection fraction when reperfusion times are between 0-3, 3-6, 6-12 and more than 12 were 70%, 59%, 32% and 0 respectively. Patients who underwent primary PCI had more chance of a preserved LVEF compared to those who underwent thrombolysis (82% Vs 44%. p=0.013). Patients with anterior wall STEMI had less number of patients with normal LVEF when reperfusion times were between 3 to 6 hours (41% Vs 93%. p=0.001) compared to non-anterior wall STEMI patients. No significant associations were found between age, presence of diabetes and the number of vessels involved to LVEF.
Conclusion :
Longer reperfusion times are associated with significant reduction in LVEF. Primary PCI leads to better outcome in patients presenting between 3-6 hours when compared with thrombolysis. AW STEMI patients develop significant reduction in LVEF at 3-6 hours compared to non-AW STEMI patients
