Author Affiliation: Harrington-McLaughlin Heart & Vascular Institute, University Hospitals Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio.
Selzman and Shein from the FDA point out that QRS morphology is also important for predicting response to CRT. In our article my colleagues and I stated, “Patients with LBBB have left ventricular activation times that are on average 36 ms longer than patients with RBBB. Consequently, the QRS duration above which CRT will be beneficial is probably significantly different with different types of conduction abnormalities”1(p1461) and called for an individual patient-level meta-analysis of all relevant clinical trials to further refine the indications for CRT.
Sipahi I. QRS Morphology Rather Than QRS Duration for Predicting CRT Response—Reply. Arch Intern Med. 2011;171(20):1861-1862. doi:10.1001/archinternmed.2011.517