QRS Axis and the Benefit of Cardiac Resynchronization Therapy in Patients with Mildly Symptomatic Heart Failure Enrolled in MADIT‐CRT

Abstract

LAD in non-LBBB patients (RBBB or IVCD) is not associated with an increased benefit from CRT. In LBBB patients, those without LAD seem to benefit more from CRT-D than those with LAD.

Prognostic Impact of QRS Axis Deviation in Patients Treated With Cardiac Resynchronization Therapy

“…There is a paucity of data examining the influence of this “axis” of ventricular activation in LBBB patients and much of it remains controversial . Notably, the presence of a left or right AD (LAD or RAD) in LBBB has been associated with more advanced cardiovascular abnormalities, resulting in an altered distribution of the impulse within the left ventricle . The aim of this study was therefore to investigate the clinical relevance of QRS axis deviation in LBBB patients undergoing CRT.…”

Absence of left bundle branch block and blood urea nitrogen predict improvement in left ventricular ejection fraction in patients with cardiomyopathy and wearable cardioverter defibrillators

“…Findings from the MADIT‐CRT have shown LBBB preventing LV reverse remodeling, and absence of LBBB or correction of LBBB using a CRT device correcting this “dyssynchrony” with improvement in LV function . Another sub‐study of the MADIT‐CRT also showed increasing heart failure events in patients with LBBB, as compared to those with RBBB or nonspecific intraventricular conduction delay . Although a QRS duration ≥150 ms has been shown to negatively predict LVEF improvement, our study lacked statistical power to support this finding.…”

“…However, data is limited regarding the clinical variables that predict improvement in LVEF. A sub‐study of the MADIT CRT trial showed that systolic blood pressure (SBP) and left bundle branch block (LBBB) predicted improvement in LVEF in patients who received an ICD . Our study aimed to determine the clinical predictors of improvement in LVEF in patients with newly diagnosed cardiomyopathy who were prescribed a WCD.…”

Adjusting the QRS Duration by Body Mass Index for Prediction of Response to Cardiac Resynchronization Therapy: Does One QRS Size Fit All?

“…[17][18][19] Although several ECG parameters have been previously studied for prediction of CRT response, [3][4][5]20 none of them gained acceptance by the current guidelines. [17][18][19] Although several ECG parameters have been previously studied for prediction of CRT response, [3][4][5]20 none of them gained acceptance by the current guidelines.…”

“…[3][4][5] However, a significant intraventricular conduction delay reflected by a prolonged QRS duration (QRSd ࣙ150 ms) with left bundle branch block (LBBB) morphology remained as the main CRT indication for patients with symptomatic heart failure and reduced ejection fraction as recommended by the current guidelines. Several ECG predictors have been tested previously to designate a parameter to correlate with outcomes after CRT.…”