PO-688-07 IMPACT OF BASELINE PR INTERVAL ON RESPONSE TO CARDIAC RESYNCHRONIZATION THERAPY: AN INDIVIDUAL PATIENT DATA META-ANALYSIS OF FIVE RANDOMIZED TRIALS

Abstract

Longer QRS duration predicts greater benefit from cardiac resynchronization therapy (CRT). Many patients receiving CRT also have a prolonged PR interval, but it is unclear whether PR interval is also an important determinant of the effects of CRT. To investigate whether PR interval is an important determinant of the benefits of CRT. Individual patient data from five randomized trials (MIRACLE, MIRACLE-ICD, CARE-HF, RAFT and REVERSE) comparing CRT and control were pooled. The composite primary endpoint was heart failure hospitalization (HFH) and all-cause mortality. Multivariable analyses were performed including PR interval as well as variables associated with heart failure outcomes including age, gender, QRS duration and morphology, heart failure etiology, systolic blood pressure, beta-blocker use, left ventricular ejection fraction (LVEF) and New York Heart Failure Association class. Of 3872 patients, 1849 were assigned to control and 2023 to CRT. Follow-up ranged from six to 40 months. There are a number of independent predictors of clinical outcomes (Table 1). However, CRT benefit on HFH or death was only significantly influenced by baseline QRS duration (p<0.0001) and PR interval (p=0.0214) and not QRS morphology (p=0.1107). For patients with QRS duration at or above the median value (160ms), the effect of CRT was substantial and similar regardless of PR interval. For patients with QRS duration below the median, CRT was effective only for those with the shortest quartile of PR interval, with progressively less evidence of benefit as PR interval became more prolonged (Table 2). PR interval as well as QRS duration are important determinants of the response to CRT. Patients with marked QRS prolongation benefit from CRT regardless of PR interval. When QRS is not as prolonged, patients with longer PR intervals may obtain little or no benefit.View Large Image Figure ViewerDownload Hi-res image Download (PPT)