Key result
CRT-D did not offer a significant survival advantage over CRT-P for all-cause mortality at long-term follow-up (HR 0.76; 95% CI 0.50-1.170; p=0.21).
Why the study?
Does CRT-D improve all-cause mortality compared to CRT-P in patients with impaired left ventricular function?
Observational (n=500)
No
Does CRT-D improve all-cause mortality compared to CRT-P in patients with impaired left ventricular function?
Hazard Ratio: 0.76 (95% CI 0.5–1.17)
Absolute Event Rate: 19.2% vs 24.8%
p-value: p=0.21
In patients with impaired left ventricular function, CRT-D did not provide a significant long-term survival advantage over CRT-P, as the initial clinical benefit attenuated over time.
Observational data leave incremental CRT-D survival benefit over CRT-P uncertain; leaves open need for RCTs to guide selection.
OBJECTIVE: Studies have shown beneficial effects of cardiac resynchronisation therapy (CRT) on mortality among patients with heart failure. However the incremental benefits in survival from CRT with a defibrillator (CRT-D) are unclear. The choice of appropriate device remains unanswered. METHOD: This is a single-centre observational study in a tertiary cardiac centre. Patients (n=500) implanted with a CRT device with pacing alone (CRT-P) (n=354) and CRT-D (n=146) were followed for at least 2 years (mean 29 months, SD 14 months). The primary end point was all-cause mortality. RESULTS: A total of 116 deaths (23.2%) were recorded: 88 (24.8%) and 28 (19.2%), in the CRT-P and CRT-D groups, respectively. At 1 year there was a trend favouring CRT-D (HR 0.54, 95% CI 0.27 to 1.07, p=0.08) but this was attenuated by the 2nd year and became insignificant at the end of follow-up (HR 0.76, 95% CI 0.50 to 1.170, p=0.21). There was no survival benefit from having an internal cardioverter-defibrillator if patients were deemed non-responders to CRT. 27% of the CRT-P patients with ischaemic cardiomyopathy met indications for potential internal cardioverter-defibrillator implantation for primary prevention. These were older patients with poorer baseline function in comparison with CRT-D patients with devices for primary prevention. Once these differences were adjusted for, there was no difference in outcome between the groups. CONCLUSIONS: CRT-D did not offer additional survival advantage over CRT-P at longer-term follow-up, as the clinical benefit of a defibrillator attenuated with time. Further work is needed to define which subset of patients benefit from CRT-D.
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Looi et al. (2014) conducted an observational in Heart failure with impaired left ventricular function (n=500). CRT-D vs. CRT-P was evaluated on all-cause mortality (HR 0.76, 95% CI 0.50-1.170, p=0.21). CRT-D did not offer a significant survival advantage over CRT-P for all-cause mortality at long-term follow-up (HR 0.76; 95% CI 0.50-1.170; p=0.21).
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