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CRT-D benefits patients with mild HF, renal dysfunction
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In patients with mild HF, renal dysfunction was associated with increased risk for HF and death, but the risk was attenuated in those who had a cardiac resynchronization therapy defibrillator, according to new findings.
Researchers assessed the impact of renal function on long-term outcomes with CRT-D in 1,820 patients with mild HF who participated in the MADIT-CRT study. Patients were stratified by QRS morphology based on the presence of left bundle branch block (LBBB). Within each strata, patients were further categorized by renal function: glomerular filtration rate (GFR) less than 60 mL/min/1.73 m2 or at least 60 mL/min/1.73 m2.
The primary endpoint was death. Secondary endpoints included HF or death and HF. Median follow-up was 5.6 years.
Usama A. Daimee, MD, and colleagues found that among the 1,274 patients with LBBB, 32% had GFR less than 60 mL/min/1.73 m2 and 68% had GFR of at least 60 mL/min/1.73 m2.
Renal dysfunction confers higher risk
Compared with those with LBBB and no renal dysfunction, patients with LBBB and renal dysfunction had a higher risk for death (HR = 2.09; 95% CI, 1.53-2.86) and combined HF/death (HR = 1.46; 95% CI, 1.17-1.82). The researchers also observed a trend toward higher risk for HF (HR = 1.28; 95% CI, 1-1.66), according to the results.
In those with LBBB, CRT-D was associated with a reduction in the risk for HF or death, as well as HF alone, and a trend toward reduced risk for death, according to the researchers. This was observed in patients with impaired renal function (HR for death = 0.66; 95% CI, 0.44-1; HR for HF or death = 0.49; 95% CI, 0.36-0.67; HR for HF = 0.36; 95% CI, 0.25-0.54) and normal renal function (HR for death = 0.68; 95% CI, 0.44-1.05; HR for HF or death = 0.5; 95% CI, 0.38-0.66; HR for HF = 0.43; 95% CI, 0.32-0.59).
Compared with patients with high GFR, those with low GFR had a greater absolute reduction in risk for death (14% vs. 6%) and death or HF (25% vs. 15%).
In patients without LBBB, those with GFR less than 60 mL/min/1.73 m2 had higher risk for death (HR = 2.08; 95% CI, 1.37-3.15), HF or death (HR = 1.84; 95% CI, 1.35-2.51) and HF (HR = 2; 95% CI, 1.4-2.86) compared with those with GFR of at least 60 mL/min/1.73 m2.
However, CRT-D was not associated with reduced risk for death, HF or death or HF compared with implantable cardioverter defibrillator only in patients without LBBB, regardless of renal function.
Encouraging findings
“Our results have important clinical implications for patients with moderate renal dysfunction who are shown in this study to derive sustained benefit during long-term follow-up from CRT-D with greater absolute risk reductions in adverse outcomes,” Daimee, from the University of Rochester Medical Center, Rochester, New York, and colleagues wrote. “These findings are encouraging for patients with moderate renal dysfunction to be considered for implantation of a CRT-D.” – by Erik Swain
Disclosure: The MADIT-CRT trial was funded by an unrestricted research grant from Boston Scientific. Daimee reports no relevant financial disclosures. Four researchers report receiving grant support from Boston Scientific.
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