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.

Trial registration: ClinicalTrials.gov NCT00733590.

Copyright © 2011 Elsevier Inc. All rights reserved.

Figures

Figure 1

Example of SAI QRST measurement. The sum of the areas under QRST curve on 3 orthogonal ECG leads is calculated.

Figure 2

Representative baseline SAI QRST ECG in a patient without (A) and one with (B) subsequent sustained ventricular tachyarrhythmia and appropriate ICD therapy at follow-up.

Figure 3

SAI QRST distribution in validation cohort patients without and with sustained VA at follow-up.

Figure 4

Kaplan-Meier curves for freedom from VT/VF events in validation cohort patients with the low, intermediate, and high SAI QRST. (A) Kaplan-Meyer all VT/VF events free survival; (B) Kaplan-Meyer MMVT events free survival; (C) Kaplan-Meyer PVT/VF events free survival.

Figure 5

Correlations between SAI QRST, body mass index (BMI) and heart function characteristics. (A) Correlation between the SAI QRST and LVDD; (B) Correlation between SAI QRST and LV EF; (C) Correlation between SAI QRST and BMI; (D) Correlation between SAI QRST and QT interval; (E) Correlation between SAI QRST and heart rate; (F) Correlation between SAI QRST and QRS width.

Figure 6

Results of ROC analysis. Receiver operating characteristic (ROC) curve on the prediction of the freedom from sustained VT/VF events. (A) for all patients; (B) for patients with narrow QRS ≤ 120ms; (C) for patients with wide QRS > 120 ms.

Figure 7

(A) Kaplan-Meier curves for freedom from VT/VF events in patients with the ICD and CRT-D device (N=508). (B) Kaplan-Meier curves for freedom from VT/VF events in CRT-D patients with the low, intermediate, and high SAI QRST.