Fragmented QRS in prediction of cardiac deaths and heart failure hospitalizations after myocardial infarction

Abstract

Background: Increased QRS fragmentation in visual inspection of 12-lead ECG has shown association with cardiac events in postmyocardial infarction (MI) patients. We investigated user-independent computerized intra-QRS fragmentation analysis in prediction of cardiac deaths and heart failure (HF) hospitalizations after MI.

Methods: Patients (n = 158) with recent MI and reduced left ventricular ejection fraction (LVEF) were studied. A 120-lead body surface potential mapping was performed at hospital discharge. Intra-QRS fragmentation was computed as the number of extrema (fragmentation index FI) in QRS. QRS duration (QRSd) was computed for comparison.

Results: During a mean follow-up of 50 months 15 patients suffered cardiac death and 23 were hospitalized for HF. Using the mean + 1 SD as cut-point both parameters were univariate predictors of both end-points. In multivariate analysis including age, gender, LVEF, previous MI, bundle branch block, atrial fibrillation, and diabetes FI was an independent predictor for cardiac deaths (HR 8.7, CI 3.0-25.6) and HF hospitalizations (HR 3.8, CI 1.6-9.3) whereas QRSd only predicted HF hospitalizations (HR 4.6, CI 2.0-10.7). In comparison to QRSd, FI showed better positive (PPA) and equal negative (NPA) predictive accuracy for both end-points, and PPA was further improved when combined to LVEF < 40%. Limiting fragmentation analysis to 12-lead ECG or a randomly selected 8-lead set instead of all 120 leads resulted in an almost similar prediction.

Conclusions: Increased QRS fragmentation in post-MI patients predicts cardiac deaths and HF progression. A computer-based fragmentation analysis is a stronger predictor than QRSd.

Figure 1

120‐lead body surface potential mapping lead positions (left) and the principle of the intra‐QRS fragmentation analysis (right). After binomial filtering the number of polarity changes or extrema (*) are computed yielding the intra‐QRS fragmentation index FI. The horizontal dashed bars indicate the onset and offset of the filtered QRS.

Figure 2

Receiver‐operator characteristics for fragmentation index FI in predicting cardiac deaths (top) and heart failure hospitalizations (bottom).

Figure 3

Receiver‐operator characteristics for QRS duration in predicting cardiac deaths (top) and heart failure hospitalizations (bottom).

Figure 4

Kaplan‐Meier actuarial curves for cardiac deaths (left) and heart failure hospitalizations (right) based on fragmentation index FI.