Cardiac contractility modulation in non-responders to cardiac resynchronization therapy

Aims Cardiac resynchronization therapy (CRT) has become a standard therapy in cases of heart failure and asynchrony. Unfortunately, 20–30 % of patients were non-responsive (NR) to CRT. In this report we used cardiac contractility modulation (CCM) as an adjunctive measure in NR patients. Methods and results Sixteen NR patients, mean age 65+9 years, mean ejection fraction 27.3+7.4%, and New York Heart Association (NYHA) class III (n 9) or IV (n 7) despite CRT plus optimized medical therapy, received an additional CCM-implantation contra-lateral to the existing CRT system (OPTIMIZER III, Impulse Dynamics, Orangeburg, NY, USA). Cardiac contractility modulation delivers non-excitatory high-energy stimulatory impulses during the absolute refractory period, thus improving contractility [left ventricular (LV) dp/dt)] by stimulating the septum with two screw-in leads and one additional atrial lead for triggering the impulses. Acute LV dp/dt changes induced by CCM stimulation were measured by 5F Millar catheters placed in the LV during the implantation procedure in 14 of 16 cases. Patients were followed prospectively. Left ventricular dp/dt increased from a mean of 568+ 153 to 646+147 mmHg/s (þ14%, P, 0.001) in the acute intraoperative testing. We noted the following complications and events during a follow-up of an average of 147+80 days (range 68–326) after CCM: intraoperative ventricular flutter needing cardioversion (n 1), atrial lead dislocation (n 1), coronar