DENVER – Levels of troponin T and brain natriuretic peptide prior to implantation of a cardiac resynchronization device were strongly predictive of the risk of death or hospitalization for heart failure during the first year of device therapy in the BENEFIT study.
BENEFIT was a 1-year observational study undertaken to determine whether markers could predict which candidates for cardiac resynchronization therapy (CRT) were least likely to benefit from the costly device. At present, roughly 30% of patients who appropriately receive a CRT device do not respond to the treatment.
"We are all at this point frustrated with the persistent portion of CRT recipients who do not respond to therapy," BENEFIT principal investigator Dr. Alaa A. Shalaby said in presenting the study findings at the annual meeting of the Heart Rhythm Society. "We think our results suggest CRT should be offered earlier in the course of the disease"
Dr. Alaa A. Shalaby
BENEFIT included 267 CRT recipients at 33 centers. Patients were placed into one of three predefined risk categories based upon baseline levels of brain natriuretic peptide (BNP) and troponin T (TnT). On the basis os prior studies, high BNP was defined as 440 pg/mL or greater and a detectible TnT level was 0.01 ng/mL or greater. The low-risk group had an undetectable TnT and a BNP below 440 pg/mL. The intermediate-risk group had either an elevated BNP or TnT. The high-risk group had elevated BNP and TnT, reported Dr. Shalaby of the University of Pittsburgh.
The median baseline BNP in the study population was 198 pg/mL.
The three groups were similar in terms of baseline characteristics, including the proportion of patients with ischemic cardiomyopathy. Based on BNP and TnT results, 59% of patients were in the low-risk category, 33% had intermediate risk, and 8% were deemed high risk. The intermediate-risk group was evenly divided between patients who qualified on the basis of a high BNP and those with a detectable TnT.
During 12 months of follow-up there were 11 deaths and 19 heart failure hospitalizations. The incidence of either endpoint was 7% in the low-risk group, 15% in the intermediate-risk group, and 30% in the high-risk cohort.
After the researchers adjusted the results for age, left ventricular ejection fraction, QRS duration, and NYHA class, the risk of death or heart failure hospitalization was 2.5-fold greater in the group with intermediate-level baseline biomarkers as in the low-risk group. The high-biomarker group had a 7.3-fold increased risk, compared with the low-biomarker cohort. Both of these differences were statistically significant.
Changes in the biomarker levels after 6 and 12 months of CRT will be the subject of a future BENEFIT analysis, he noted.
The BENEFIT study was supported by St. Jude Medical. Dr. Shalaby reported having no conflicts of interest.