The interaction of sex, height, and QRS duration on the effects of cardiac resynchronization therapy on morbidity and mortality: an individual-patient data meta-analysis.

AIMS: To explore possible associations that may explain the greater benefit from cardiac resynchronization therapy (CRT) reported amongst women. METHODS AND RESULTS: In an individual-patient data meta-analysis of five randomized controlled trials, all-cause mortality and the composite of all-cause mortality or first hospitalization for heart failure (HF) were compared among 794 women and 2702 men assigned to CRT or a control group. Multivariable analyses were performed to assess the impact of sex, QRS duration, HF aetiology, left ventricular end-diastolic diameter (LVEDD), and height on outcome. Women were shorter, had smaller LVEDD, more often left bundle branch block, and less often ischaemic heart disease, but QRS duration was similar between sexes. Women tended to obtain greater benefit from CRT but sex was not an independent predictor of either outcome. For all-cause mortality, QRS duration was the only independent predictor of CRT benefit. For the composite outcome, height and QRS duration, but not sex, were independent predictors of CRT benefit. Further analysis suggested increasing benefit with increasing QRS duration amongst shorter patients, of whom a great proportion were women. CONCLUSIONS: In this individual-patient data meta-analysis, CRT benefit was greater in shorter patients, which may explain reports of enhanced CRT benefit among women. Further analyses are required to determine whether recommendations on the QRS threshold for CRT should be adjusted for height. (ClinicalTrials.gov numbers: NCT00170300, NCT00271154, NCT00251251).

An individual patient meta-analysis of five randomized trials assessing the effects of cardiac resynchronization therapy on morbidity and mortality in patients with symptomatic heart failure.

AIMS: Cardiac resynchronization therapy (CRT) with or without a defibrillator reduces morbidity and mortality in selected patients with heart failure (HF) but response can be variable. We sought to identify pre-implantation variables that predict the response to CRT in a meta-analysis using individual patient-data. METHODS AND RESULTS: An individual patient meta-analysis of five randomized trials, funded by Medtronic, comparing CRT either with no active device or with a defibrillator was conducted, including the following baseline variables: age, sex, New York Heart Association class, aetiology, QRS morphology, QRS duration, left ventricular ejection fraction (LVEF), and systolic blood pressure. Outcomes were all-cause mortality and first hospitalization for HF or death. Of 3782 patients in sinus rhythm, median (inter-quartile range) age was 66 (58-73) years, QRS duration was 160 (146-176) ms, LVEF was 24 (20-28)%, and 78% had left bundle branch block. A multivariable model suggested that only QRS duration predicted the magnitude of the effect of CRT on outcomes. Further analysis produced estimated hazard ratios for the effect of CRT on all-cause mortality and on the composite of first hospitalization for HF or death that suggested increasing benefit with increasing QRS duration, the 95% confidence bounds excluding 1.0 at ∼140 ms for each endpoint, suggesting a high probability of substantial benefit from CRT when QRS duration exceeds this value. CONCLUSION: QRS duration is a powerful predictor of the effects of CRT on morbidity and mortality in patients with symptomatic HF and left ventricular systolic dysfunction who are in sinus rhythm. QRS morphology did not provide additional information about clinical response. CLINICALTRIALSGOV NUMBERS: NCT00170300, NCT00271154, NCT00251251.