The Shortest QRS Duration of an Electrocardiogram Might Be an Optimal Electrocardiographic Predictor for Response to Cardiac Resynchronization Therapy

Abstract

SummaryQRS duration has been associated with the response to cardiac resynchronization therapy (CRT). However, the methods for defining QRS duration to predict the outcome of CRT have discrepancies in previous reports. The aim of this study was to determine an optimal measurement of QRS duration to predict the response to CRT.Sixty-one patients who received CRT were analyzed. All patients had class III-IV heart failure, left ventricular ejection fraction not more than 35%, and complete left bundle branch block. The shortest, longest, and average QRS durations from the 12 leads of each electrocardiogram (ECG) were measured. The responses to CRT were determined using the changes in echocardiography after 6 months. Thirty-five (57.4%) patients were responders and 26 (42.6%) patients were non-responders. The pre-procedure shortest, average, and longest QRS durations and the QRS shortening (ΔQRS) of the shortest QRS duration were significantly associated with the response to CRT in a univariate logistic regression analysis (P = 0.002, P = 0.03, P = 0.04 and P = 0.04, respectively). Based on the measurement of the area under curve of the receiver operating characteristic curve, only the pre-procedure shortest QRS duration and the ΔQRS of the shortest QRS duration showed significant discrimination for the response to CRT (P = 0.002 and P = 0.038, respectively). Multivariable logistic regression showed the pre-procedure shortest QRS duration is an independent predictor for the response to CRT.The shortest QRS duration from the 12 leads of the electrocardiogram might be an optimal measurement to predict the response to CRT. (Int Heart J 2017; 58: 530-535) Key words: Heart failure C ardiac resynchronization therapy (CRT) is a wellknown procedure for improving left ventricular function via reverse remodeling in patients with heart failure.1) The QRS durations before implantation and at follow-up may predict the patient's response to CRT, especially in the presence of left bundle branch block (LBBB).2-8) However, the QRS durations are usually different and diverse among the 12-lead electrocardiogram (ECG). 9) Additionally, in previous reports, the methods to define the QRS duration in predicting a CRT patient's outcome have discrepancies and lack standardization of QRS duration measurement.10) Many different methods for QRS duration measurement have been used in previous studies, including the QRS duration of one selected lead, 11,12) the longest QRS duration, 13) the average QRS duration of 12 leads, 14) and undefined. 6,15,16) International guidelines for heart failure management also have not recommended a preferred standard measurement technique for QRS duration for CRT.2,10,17,18) Lack of standard measurement in the QRS duration might have a significant influence on the conclusions of different studies.10) Thus, this is the crucial reason why the recommended QRS duration for CRT implantation was different and variable in previous reports. However, the decision-making for suggesting that a patient receive a CRT implanta...

Prognostic Implications of QRS Duration in Third-Degree Atrioventricular Block Patients with Heart Failure Treated with Cardiac Resynchronization Therapy

“…23,24) However, patients with baseline QRS duration "150 ms showed narrowed QRS duration following biventricular pacing, with significantly improved cardiac functions. [25][26][27] In patients with third-degree AVB, pacing QRS duration was not associated with the location of the conduction block 28) but was correlated with baseline QRS duration. 28,29) In this study, patients with QRS duration < 120 ms showed significantly widened QRS duration after biventricular pacing, with poor response to CRT, while patients with QRS duration "150 ms had remarkably shortened QRS duration following biventricular pacing, with a response rate to CRT as high as 76.5%.…”