Prognostic markers in the acute phase of myocardial infarction

Introduction

The aim of the study was to assess the prognostic value of heart rate variability, arrhythmias and left ventricular systolic and diastolic function for the course and the outcome of myocardial infarction (MI).

Methods

We prospectively studied 57 consecutive patients admitted to the ICU of the Department of Cardiology of Kaunas Medical University Hospital between 2002 and 2004 with acute MI. The study protocol included 24-hour ECG monitoring on the first day and the third day of admission and echocardiography performed at days 2–4. Inhospital prognostic endpoints were death and nonfatal events: postinfarction angina, progressive heart failure, pulmonary edema and cardiogenic shock. Heart rate variability (HRV) was assessed at days 1 and 3 by a 24-hour recording using the 'HeartLab' system. A logistic regression model was used to select the combination of statistically significant variables and predict the complications.

Results

In our model statistically significant independent variables for prediction of inhospital MI complications were HRV frequency domain parameter low-frequency power (LF) on day 3, and left ventricular end-systolic volume (LV ESV), atrial fibrillation/flutter and inotropic agent administration on day 1. According to the results, atrial fibrillation/flutter (odds ratio 25.6) and increased LV ESV (odds ratio 1.067 (6.7%) for increase in 1 ml) increase the probability of inhospital complications, while increased LF on day 3 (odds ratio 1.29 for 1,000 units) and no administration of inotropic drug on day 1 (odds ratio 34.5) decrease the probability of inhospital complications. The average efficacy of prognostication reached 96.5%; the presence of complications was correctly predicted in 88.9% of cases, and the absence of complications in 100% of cases.

Conclusion

The HRV parameter LF on day 3, and LV ESV, atrial fibrillation/flutter and inotropic agent administration on day 1 are statistically significant independent predictors of inhospital complications of MI with an average predictive efficacy of 96.5%.