Heart rate variability in early phase of acute myocardial infarction and convalescence.

Abstract This study was done to evaluate the degree of change in autonomic activity, manifested as heart rate variability (HRV), from acute phase of MI to convalescent period of AMI. Single center, observational prospective study. Department of Cardiology, Shaikh Zayed Hospital, Lahore. The study was completed in one year from June 2000 to July 2001. Thirty consecutive patients presenting within 24 hours of an ST segment elevation AMI with or without thrombolysis were included. First 24 hour Holter recording was done within 24-36 hours after AMI and the second was done before discharge. The mean hospital stay was 7.07 +/- 2.56 days. Mean duration between the two recordings was 5.47 +/- 2.36 days. The mean standard deviation of normal sinus interval (SDNN) was 65.07 +/- 25.11msec & 63-97 +/- 23.38msec; mean standard deviation of averaged sinus beats for 5 minutes segments of entire recording (SDANN) was 51.27 +/- 18.57msec and 55.83 +/- 19.65msec and mean SDDN index was 34.57 +/- 17.15msec and 30.57 +/- 14.89msec during early phase of acute MI & pre-discharge recordings respectively. There was no statistically significant difference in HRV between early phase of acute myocardial infarction and of pre-discharge recordings. HRV may be monitored for risk stratification at any time post AMI prior to discharge.