Background: Cardiac resynchronization therapy (CRT) has been shown to confer both symptomatic and prognostic advantage in selected patients with low ejection fraction and heart failure (HF). Patients with narrow complex QRS do not derive clear clinical benefit. This lack of effect might be due to incomplete resynchronization. Multisite left ventricular CRT (MSCRT) – i.e. two pacing leads on the LV (postero-lateral (PL) and antero-lateral (AL) branches of coronary sinus) - has theoretical advantages in faster and more physiological LV activation. Our previous experience shows feasibility and safety of MSCRT implantation.
Aim: To investigate prospectively the efficacy of MSCRT implantation in severe HF patients with narrow QRS and an indication for ICD implantation.
Methods: Patients with severe LV dysfunction, HF NYHA ≥3 on optimal medications, dyssynchrony (using dyssynchrony index by 3-dimensional echo) and narrow QRS were included and implanted with MSCRT defibrillator. Each patient served as his own control: CRT configuration for one month and MSCRT configuration for one month (in a blinded order). The clinical evaluation (quality of life questionnaires, 6-minute-walk, echocardiography and non-invasive measurement of cardiac output) was done blindly at baseline and after one month in each configuration.
Results: Out of eleven patients included (82% male, 91% ischemic heart disease) – three patients were excluded - one was lost to follow-up, one had AF with low MSCRT/biventricular pacing (BVP), and one had higher threshold in AL than PL branch. In five patients (62%) there was improvement in EF, NYHA Class and clinical evaluation with MSCRT versus baseline and versus BVP. In two patients (25%) there was improvement in these parameters versus baseline but no difference between MSCRT and BVP. In one patient (12.5%) there was a worsening of parameters with MSCRT with worsening mitral regurgitation versus an improvement with BVP.
Conclusion: Our results in a small group of patients show that CRT may improve quality of life, ejection fraction and cardiac output in patients with severe HF and narrow complex QRS. Larger studies are needed for further validation.
