Abstract 4851: One Year Follow-Up of CRT in Narrow QRS Patients with Mechanical Dyssynchrony: ESTEEM-CRT
CRT is standard therapy for patients with systolic heart failure and QRS > 120 ms. Prior single-center studies suggest CRT benefits patients with a narrow QRS (NQRS < 120 ms) in the presence of mechanical dyssynchrony (MD) as defined by echocardiography. But recent multi-center studies report that NQRS patients may not improve after 6 months of pacing. There is very little long-term data on the efficacy of CRT in these NQRS patients from multi-center sources. ESTEEM-CRT was a multi-center, single-arm, unblinded, feasibility study that evaluated the acute and chronic effects of CRT in patients with a NQRS and MD. Enrollment criteria were optimal pharmacologic therapy, EF ≤ 35%, NYHA Class III, QRS < 120ms, and MD as defined by the standard deviation of time to peak velocity of 12 segments (Ts-SD) > 28.7 ms using GE Vivid 7 machines. All patients received a CRT defibrillator and a subset underwent invasive LV dP/dtmax testing for AV optimization at implant. One month after implant, patients underwent baseline evaluation (CPX and echo) and CRT was turned on. Follow-up was 6 months later, and a substudy followed patients for 12 months. Statistical significance for NYHA class trend over time was evaluated by an exact correlation Mantel-Haenszel statistic. Differences in the means for quality of life (QOL), LVESV, and LVEDV were tested using repeated measures models. Demographics: n = 67; QRS = 102 ± 10 ms; age = 58 ± 14 years; 67% male; 60% ischemic, 66% hypertensive, 96% beta-blockers, 88% ACEI/ARB. Patients’ symptoms and QOL scores were improved at both 6 and 12 months, while LV volumes were unchanged throughout (see Table⇓). ESTEEM-CRT showed that patients with a NQRS and MD did not exhibit any change in LV size throughout 12 months of CRT. Symptomatic and quality of life improvements, though retained long-term, may be due to bias and/or placebo effect. Further controlled study is needed to fully understand the therapeutic impact of CRT in these patients.