QRS integral: an electrocardiographic indicator of mechanical interventricular asynchrony

Aim: The aim of this study was to investigate whether interventricular asynchrony (IVA) can be measured by electrocardiography.

Methods: Sixty-two patients (New York Heart Association heart failure functional class III: age, mean +/- SD: 64 +/- 9 years; ejection fraction, mean +/- SD: 24% +/- 8%; dilative cardiomyopathy/ischemic cardiomyopathy, n = 39/23) with left bundle branch block (QRS duration, mean +/- SD: 165 +/- 21 milliseconds) underwent a 120-channel body surface mapping. QRS integral was analyzed and compared with IVA (echo).

Results: Interventricular asynchrony was associated with significantly decreased QRS integrals 15 cm cranial and 6 cm lateral from V1 in patients with normal axis (n = 36): At a cutoff value of -26 milliseconds mV, receiver operating characteristic analysis to predict IVA revealed a sensitivity of 89% and a specificity of 83% (area under curve, mean +/- SEM: 0.9 +/- 0.07; P < .001). In patients with left axis deviation (n = 26), IVA showed significantly decreased QRS integrals 10 cm caudal from V1: at a cutoff value of -89 milliseconds mV, receiver operating characteristic analysis to predict IVA revealed a sensitivity of 83% and a specificity of 100% (area under curve, mean +/- SEM: 0.9 +/- 0.07; P < .002).

Conclusions: Interventricular asynchrony strongly correlates with QRS integral. Key lead positions, however, are axis dependent and outside standard leads.