Sympathetic Overactivity in Patients With Left Ventricular Aneurysm in Early Period After Anterior Myocardial Infarction: Does Sympathetic Activity Predict Aneurysm Formation?

Abstract

Left ventricular aneurysm (LVA) is an important complication of acute transmural myocardial infarction (MI) that bears great clinical significance because of high mortality. Heart rate variability (HRV) analysis is extensively used to evaluate autonomic modulation of sinus node and to identify patients at risk for an increased cardiac mortality. In this study, the authors evaluated HRV in patients with LVA in the early period after acute anterior wall MI. They compared 18 patients (7 men, 11 women, with an average age of 56.1 ±8.2 years) with LVA and 46 patients (34 men, 12 women, with an average age of 56.4 ±5.9 years) without LVA. Mean heart rate, low frequency (LF) and low-frequency/high-frequency (LF/HF) ratio were significantly higher and standard deviation of normal-to-normal RR intervals (SDNN), root mean square of successive differences (RMSSD), number of NN intervals that differed by more than 50 ms from adjacent interval divided by the total number of all NN intervals (PNN50), and HF were lower in the patients with LVA. A SDNN <78 ms separated the patients with aneurysm from those without aneurysm with a sensitivity of 78%, specificity of 83%, positive predictive accuracy of 79%; a LF/HF ratio >2.4 with a sensitivity of 92%, specificity of 88%, and positive predictive accuracy of 92%. Single-vessel disease increased the left ventricular aneurysm formation by 5.1 fold, total left anterior descending artery (LAD) occlusion by 3.1 fold, mean heart rate >75 beats/minute by 2.3 fold, SDNN <78 ms by 7.9 fold, and LF/HF ratio >2.4 by 12.9 fold, but well-developed collaterals decreased the aneurysm formation by 4.4 fold. As a result, HRV analysis supplies parameters with high predictive value for LVA formation in the early period after acute anterior MI. The higher sympathetic activity and reduced heart rate variability may be associated with a higher incidence of complications such as ventricular arrhythmias and increased mortality in patients with LVA.