Atrioventricular delay programming and the benefit of cardiac resynchronization therapy in MADIT-CRT

Abstract

Background: The optimal atrioventricular pacing delay (AVD) in cardiac resynchronization therapy (CRT) remains to be determined.

Objective: To determine whether programming CRT devices to short AVD (S-AVD) will improve clinical response secondary to greater reductions in dyssynchrony.

Methods: The study population comprised 1235 patients with left bundle branch block enrolled in Multicenter Automatic Defibrillator Implantation Trial in Cardiac Resynchronization Therapy (MADIT-CRT). We assessed the relationship between AVD and outcomes. Patients programmed to S-AVD (median value of <120 ms; n = 337) vs long AVD (L-AVD; ≥120 ms; n = 390) were assessed for the end points of heart failure (HF) or death, death alone, and echocardiographic response to the CRT at 1-year follow-up. Outcomes were also compared to the left bundle branch block implantable cardioverter-defibrillator-only group (n = 508).

Results: Multivariate analysis showed that patients programmed to S-AVD experienced a significant 33% (hazard ratio [HR] 0.67; 95% confidence interval [CI] 0.44-0.85; P = .037) reduction in the risk of HF or death and a 47% (HR 0.53; 95% CI 0.29-0.94; P = .031) reduction in death alone as compared with those programmed to L-AVD. Patients with CRT-programmed S-AVD and L-AVD experienced 63% (HR 0.37; 95% CI 0.26-0.53; P < .001) and 46% (HR 0.54; 95% CI 0.31-0.96; P < .001) reduction, respectively, in the risk of HF or death compared to patients with implantable cardioverter-defibrillator alone. At 1 year of follow-up, S-AVD vs L-AVD was associated with a greater reduction in left ventricular end-systolic volume (34.2% vs 30.8%; P = .002) along with a significantly greater improvement in dyssynchrony (22.3% vs 9.4%; P = .036).

Conclusions: Our findings indicate that in MADIT-CRT programming, the CRT AVD <120 ms was associated with a greater clinical and echocardiographic response to CRT.

Keywords: AVD; Atrioventricular delay; CI; CRT-D; Cardiac resynchronization therapy; HF; HR; Heart failure; ICD; IQR; L-AVD; LBBB; LV; LVEDV; LVESV; MADIT-CRT; Multicenter Automatic Defibrillator Implantation Trial in Cardiac Resynchronization Therapy; NYHA; New York Heart Association; S-AVD; SMART-AV; Smart Delay determined AV optimization: A comparison of AV optimization methods used in cardiac resynchronization therapy; atrioventricular delay; cardiac resynchronization therapy-defibrillator; confidence interval; hazard ratio; heart failure; implantable cardioverter-defibrillator; interquartile range; left bundle branch block; left ventricle/ventricular; left ventricular end-diastolic volume; left ventricular end-systolic volume; long AVD; short AVD.