DEFEAT-HF: Spinal cord stimulation did not benefit patients with HF

CHICAGO — Implantation of a spinal cord stimulator was not associated with clinical benefit or improvement in outcomes as a treatment for advanced HF.

Douglas P. Zipes, MD, and colleagues of the DEFEAT-HF trial hypothesized that spinal cord stimulation (Prime Advanced Neuromodulator and standard 1x8 lead Model 3777, Medtronic) powered to 90% maximum tolerated threshold voltage would reverse remodel patients with NYHA class III HF and narrow QRS.

Douglas P. Zipes

The researchers randomly assigned 66 patients who were implanted with the spinal cord stimulator on a 3:2 basis to activation for 12 hours per day for 6 months or no activation for 6 months. At the 6-month mark, patients in the control group had their stimulators switched on and all patients continued to be followed annually. Sixty patients were analyzed; the other six died, did not complete 6-month follow-up or had an unreadable echocardiogram.

The primary outcome was change in left ventricular end-systolic volume index at 6 months. Secondary outcomes included change in peak oxygen uptake at 6 months and change in N-terminal pro–B-type natriuretic peptide levels at 6 months.

At 6 months, LV end-systolic volume index increased by 2.8 mL/m² in the therapy group and decreased by –3.6 mL/m²in the control group (P=.3), Zipes, from the Krannert Institute of Cardiology at the University of Indiana School of Medicine, Indianapolis, reported at the American Heart Association Scientific Sessions.

Mean change in peak VO₂ was 0.6 mL/kg/min in the therapy group and –0.2 mL/kg/min in the control group (P=.93). Mean change in NT-proBNP was –32 pg/mL for the therapy group and 74 pg/mL for controls (P=.79), according to Zipes.

There were no differences between the groups in freedom from death or hospitalization for HF at 6 months (P=.28), change on Minnesota Living with Heart Failure Score (P=.9), change in NYHA class (P=.7) or change in 6-minute walk distance (P=.47). Zipes also noted that there were no differences between the groups in adverse events resulting in complications (P=.95), and no type of complication occurred in more than 5% of patients.

Twelve-month data were similar to 6-month data, according to Zipes. Although one center randomly assigned one-third of the patient population, analysis of the data without those patients did not change the results, he said.

“This does not necessary invalidate the hypothesis of spinal cord stimulation benefits,” Zipes said. “[The trial] was low-powered, enough to establish neutral effects, but not for analyzing subgroups to understand why. Perhaps we had incorrect spinal cord stimulation dosing. Perhaps we should have used 24 hours per day instead of 12, a higher output, or maybe two leads. We could have included [cardiac resynchronization therapy] nonresponders but did not. Have these facts slain the hypothesis, or have we not tested the hypothesis appropriately?” – by Erik Swain

For more information:

Zipes DP. CS.02: Off the Beaten Pathologies. Presented at: American Heart Association Scientific Sessions; Nov. 15-19, 2014; Chicago.

Disclosure: The study was funded by Medtronic. Zipes reports receiving a research grant from and consulting for Medtronic.