ASSOCIATION OF VIABILITY OF MYOCARDIUM WITH PARAMETERS OF HEART RATE VARIABILITY IN PATIENTS OF FIRST ANTERIOR MYOCARDIAL INFARCTION

Background & Objective: Heart rate variability (HRV) is depressed after acute myocardial infarction (MI) and has been considered as a powerful predictor of mortality and arrhythmic complications in patients of MI. The present study was done to evaluate whether presence of viable tissue within the akinetic myocardium in MI patients, as assessed by dobutamine stress echocardiography (DSE), has any influence on the parameters of HRV. Methods: 51 patients with anterior wall ST elevation myocardial infarction (STEMI) treated conservatively underwent DSE two weeks after the index event of MI for assessment of myocardial viability. HRV recording was done for 20 minutes in these patients. Results: Out of 51 patients, 26 were DSE positive and 25 were DSE negative for viable myocardium. Among DSE positive group, the first 25 patients were taken for comparative analysis. Only the time domain parameters of HRV were significantly high in patients in the DSE positive group as compared to that observed in DSE negative group. On logistic regression analysis, only pNN50 (with p value = 0.021) could make a significant contribution for prediction of myocardial viability in the patients of MI. When pNN50 value increased by one unit, it was 1.43 times more likely to predict viable myocardium. Conclusion: The presence of viable myocardial tissue in akinetic segments among patients of first anterior wall STEMI influences the time domain as well as frequency domain HRV measures. HRV could be used as a potential screening tool to detect myocardial viability in patients of MI.