A new electrocardiogram marker to identify patients at low risk for ventricular tachyarrhythmias: sum magnitude of the absolute QRST integral

Abstract Objective We proposed and tested a novel electrocardiogram marker of risk of ventricular arrhythmias (VAs). Methods Digital orthogonal electrocardiograms were recorded at rest before implantable cardioverter-defibrillator (ICD) implantation in 508 participants of a primary prevention ICDs prospective cohort study (mean ± SD age, 60 ± 12 years; 377 male [74%]). The sum magnitude of the absolute QRST integral in 3 orthogonal leads (SAI QRST) was calculated. A derivation cohort of 128 patients was used to define a cutoff; a validation cohort (n = 380) was used to test a predictive value. Results During a mean follow-up of 18 months, 58 patients received appropriate ICD therapies. The SAI QRST was lower in patients with VA (105.2 ± 60.1 vs 138.4 ± 85.7 mV ⁎ ms, P = .002). In the Cox proportional hazards analysis, patients with SAI QRST not exceeding 145 mV ⁎ ms had about 4-fold higher risk of VA (hazard ratio, 3.6; 95% confidence interval, 1.96-6.71; P < .0001) and a 6-fold higher risk of monomorphic ventricular tachycardia (hazard ratio, 6.58; 95% confidence interval, 1.46-29.69; P = .014), whereas prediction of polymorphic ventricular tachycardia or ventricular fibrillation did not reach statistical significance. Conclusion High SAI QRST is associated with low risk of sustained VA in patients with structural heart disease.