(HealthDay News) – Among Medicare beneficiaries undergoing cardiac resynchronization therapy defibrillator (CRT-D) implantation, the risk of all-cause mortality and readmission is lowest for those patients with left bundle-branch block (LBBB) and QRS duration of ≥150ms, according to a study published in the Aug. 14 issue of the Journal of the American Medical Association.

Pamela N. Peterson, MD, MSPH, from Denver Health Medical Center, and colleagues examined the correlation between QRS duration and morphology and outcomes in a retrospective study involving 24,169 Medicare beneficiaries in the National Cardiovascular Data Registry’s Implantable Cardioverter-Defibrillator Registry who underwent CRT-D implantation between 2006 and 2009. Patients were categorized as having LBBB or no LBBB, and according to QRS duration (120–149ms or ≥150ms).

The researchers found that the mortality rates were 9.2% and 25.9%, respectively, at one and three years. At 30 days and one year, the all-cause readmission rates were 10.2% and 43.3%, respectively. Patients with LBBB and QRS duration of ≥150ms had the lowest unadjusted rate and adjusted risk of three-year mortality and one-year all-cause readmission. The correlations were observed with no complications.

“These findings support the use of QRS morphology and duration to help identify patients who will have the greatest benefit from CRT-D implantation,” the authors write.

Several authors disclosed financial ties to the pharmaceutical and medical device industries.

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