Prognostic Implications of Right Ventricular Size and Function in Patients Undergoing Cardiac Resynchronization Therapy

Abstract

C ardiac resynchronization therapy (CRT) is an established treatment for patients with symptomatic chronic heart failure, reduced left ventricular ejection fraction (≤35%), and a QRS duration ≥130 ms. 1 Furthermore, chronic left ventricular failure is the most frequent cause of right ventricular (RV) adverse remodeling, a complex process consisting of progressive RV dilatation and dysfunction. 2 Both parameters individually, RV dilatation and RV dysfunction, are important prognostic markers in CRT-recipients. 3,4 However, the prognostic value of both parameters in a single model has not been evaluated. Accordingly, this study evaluated the prognostic value of RV remodeling in CRT-recipients. CRT-recipients with echocardiographic data on RV remodeling, before CRT implantation (both CRT-D and CRT-P), were identified from the departmental database of the Leiden University Medical Center (Leiden, The Netherlands). RV remodeling was assessed by RV size (measured by indexed RV end-diastolic area [right ventricular end-diastolic area−indexed for body surface area] using sex-specific cutoff values to define RV dila-tation: right ventricular end-diastolic area−indexed for body surface area >12.6 cm 2 /m 2 for men and right ven-tricular end-diastolic area−indexed for body surface area >11.5 cm 2 /m 2 for women) and RV function (measured by tricuspid annular plane systolic excursion) with tricus-pid annular plane systolic excursion <17 mm considered as a reduced RV function). 5 Subsequently, patients were classified into 4 remodeling patterns: (1) normal RV size and function; (2) RV dilatation and normal RV function; (3) normal RV size and RV dysfunction; (4) RV dilatation and RV dysfunction (Figure). The primary end point was all-cause mortality. Cumulative survival rates were calculated using the Kaplan-Meier method. To investigate the association between RV size and RV function with all-cause mortality , multivariable Cox proportional hazards regression analysis was performed, adjusting for variables known to have an impact on prognosis. The incremental prognos-tic value of RV size and RV function was assessed by likelihood-ratio testing evaluating the change in global χ 2 values. This retrospective analysis was approved by the institutional review board of the Leiden University Medical Center, and the need for patient written informed consent was waived. The research reported in this article adhered to the Helsinki Declaration. The data that support the findings of this study are available from the corresponding author upon reasonable request. Of the 773 patients (mean age 66±10 years, 75% males) included, 264 (34%) patients had pattern 1, 101 (13%) had pattern 2, 256 (33%) had pattern 3, and 152 (20%) had pattern 4, prior to CRT implantation. A total of 414 (54%) patients had an ischemic cause of heart failure. A total of 739 (96%) patients received CRT-D, and only 34 (4%) patients had CRT-P with a comparable distribution among the 4 remodeling patterns. Overall, 130 (17%) patients had atrial fibrillation, and the mean QRS duration was 168±26 ms. Mean left ventricular ejection fraction was 27±8%, mean right ventricular end-diastolic area−indexed for body surface area was 11.5±3.5 cm 2 /m 2 , and mean tricuspid annular plane sys-tolic excursion was 16±5 mm. When comparing the 4 RV remodeling patterns, ischemic cause varied significantly