Nonexcitatory, cardiac contractility modulation electrical impulses: feasibility study for advanced heart failure in patients with normal QRS duration.

Background: Cardiac contractility modulation signals are associated with acutely improved hemodynamics, but chronic clinical impact is not defined.

Objectives: The purpose of this randomized, double-blind, pilot study was to determine the feasibility of safely and effectively delivering cardiac contractility modulation signals in patients with heart failure.

Methods: Forty-nine subjects with ejection fraction <35%, normal QRS duration (105 +/- 15 ms), and New York Heart Association (NYHA) class III or IV heart failure despite medical therapy received a cardiac contractility modulation pulse generator.