Abstract 2482: Quantification of Myocardial Scar Using a Simple ECG Tool Identifies Patients at Risk for Sudden Arrhythmic Death: An Analysis of SCD-HeFT
Background: Myocardial scar provides a substrate for malignant ventricular arrhythmias. The Selvester 12-lead ECG QRS-scoring systems estimate scar size from changes in Q-, R-, and S-wave durations, amplitudes and notches with each QRS point representing 3% of the left ventricle. QRS scoring has been validated against contrast-enhanced magnetic resonance imaging in ischemic and nonischemic cardiomyopathy. We tested the hypothesis that low ECG-estimated scar by QRS scoring would identify patients with reduced occurrence of VT/VF and/or sudden arrhythmic death in the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) population.
Methods and Results: We studied 797 patients (410 ischemic, 387 nonischemic) from the implantable cardioverter-defibrillator (ICD) arm of SCD-HeFT who had adequate baseline 12-lead ECGs for scoring (98% of ICD patients). During a median 45.5 month follow-up, 24% of patients had VT/VF treated by the ICD and/or sudden arrhythmic death. By univariate Cox proportional-hazards, QRS score as a continuous variable (per 3 QRS point increase) significantly predicted outcome (HR 1.12, 95% CI 1.0–1.2, p=0.04), along with 6 of 10 other clinically relevant variables. After multivariate adjustment, QRS score remained significant (adjusted HR 1.13, 95% CI 1.0–2.9, p=0.05). Similarly, when assessed as a dichotomous variable (QRS score ≥1 [n=696] vs 0 [n=101]), QRS score had the highest univariate HR of 1.9, 95% CI 1.1–3.3, p=0.015 (see Table⇓). After multivariate adjustment, dichotomous QRS score had the HR of 1.7, 95% CI 1.0–2.9, p=0.05.
Conclusions: ECG-estimated scar size by QRS score independently predicts risk of VT/VF and/or sudden arrhythmic death. Identification of myocardial scar by QRS scoring should be included in current risk-stratifying schemes for selecting patients for ICDs.