Reduced Ejection Fraction, Sudden Cardiac Death, and Heart Failure Death in the Mode Selection Trial (MOST): Implications for Device Selection in Elderly Patients with Sinus Node Disease

Background: The purpose of this study was to describe the incidence and predictors of sudden cardiac death (SCD) and heart failure (HF) death, and coexisting indications for ICDs and CRT, in patients with sinus node disease (SND) treated with pacemakers. Methods and Results: Baseline variables were used to predict SCD and HF death among 1,135 patients in the Mode Selection Trial, a 6-year trial of pacing mode in SND. There were 73 deaths among 177 patients with EF ≤ 35% (41.2%), 46/156 (29.5%) with EF 36–49%, and 147/802(18.3%) with EF ≥ 50%. SCD accounted for 21.9%, 23.9%, and 14.3% of deaths with EF ≤ 35%, 36–49%, and ≥ 50%. HF deaths accounted for 23.3%, 19.6%, and 3.4% of deaths with EF ≤ 35%, 36-49%, and ≥ 50%. EF ≤ 35% predicted SCD (hazard ratio [HR] 3.68, 95% confidence interval [CI] 1.72-7.89, P = 0.002) and HF death (HR 10.17, 95% CI 3.35, 30.82, P = 0.001). Four-year SCD rate with EF ≤ 35% was 15.5% (3.9% annually). Nearly one-fifth of patients qualified for ICDs (EF ≤ 35%) and half of these had QRS ≥ 120 ms. However, >40% died within 33 months (4-year noncardiac death rate ∼22%). Conclusions: Reduced EF predicts SCD and HF death in SND treated with pacemakers. SCD rates among patients with EF ≤ 35% are similar to control arms of primary prevention ICD trials, but mortality rates are significantly higher. Whether ICDs or CRT to provide bradycardia support would prolong life in elderly patients with EF ≤ 35% and SND merits prospective investigation.