Association of prolonged QRS duration with ventricular tachyarrhythmias and sudden cardiac death in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II)

In patients with prior myocardial infarction and EF ≤30%, prolonged QRSd does not predict SCD/VT/VF in ICD-treated patients but does predict SCD in medically treated patients. This underscores the nonequivalence of VT/VF and SCD and the need for caution in inferring risk of SCD when using nonrandomized databases that include only patients with ICDs.