Objectives: The aim of this study was to determine whether QRS duration (QRSd) correlates with occurrence of ventricular arrhythmia in patients with coronary disease (CAD) receiving implantable cardioverter-defibrillators (ICDs).
Background: A QRSd measured on a standard electrocardiograph (ECG) correlates with total mortality risk in CAD patients at high risk for sudden death; however, the relationship between QRSd and risk of ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) is unclear.
Methods: PainFREE Rx II was a randomized trial, comparing efficacy of antitachycardia pacing versus shock therapy for VT/VF in patients receiving ICDs. We retrospectively correlated the QRSd and specific ECG conduction abnormalities on the 12-lead ECG at study entry with occurrence of VT/VF in 431 patients with CAD enrolled in the trial.
Results: The QRSd was < or =120 ms in 291 of 431 (68%) patients. Left bundle branch block (LBBB) was present in 65 patients, right bundle branch block (RBBB) in 48 patients, and nonspecific intraventricular conduction delay (IVCD) was present in 124 patients. Over 12 months' follow-up, VT/VF occurred in 95 (22%) patients (22% of patients with QRSd < or =120 ms vs. 23% of patients with QRSd >120 ms, p = NS). Patients with LBBB were less likely to experience at least one VT/VF episode than patients with QRSd <120 ms. Patients with RBBB and nonspecific IVCD did not differ from patients with narrow QRS complexes with regard to occurrence of tachycardias.
Conclusions: The QRSd and ECG conduction abnormalities are not useful to predict ICD benefit in patients having the characteristics of our study population. The utility of QRSd to predict VT/VF events in patients with CAD requires further prospective evaluation.