Long-term prognosis of patients with chronic heart failure and reduced left ventricular ejection fraction receiving cardiac contractility modulation therapy: the impact of comorbidity burden on outcomes

Aim . To investigate the association between comorbidity burden and long-term clinical outcomes of patients with reduced left ventricular ejection fraction (HFrEF) undergoing cardiac contractility modulation (CCM). Methods . Our study included 59 patients with HFrEF, functional class II/III (NYHA), sinus rhythm, who underwent implantation of CCM system between September 2015 and December 2018 and were further followed by a multidisciplinary team. A mean follow-up period was 1916±102 days. All-cause mortality and heart transplantation were considered as primary composite endpoint. The secondary composite endpoint included all-cause mortality, heart transplantation, im- plantable cardioverter defibrillator shocks due to ventricular tachyarrhythmia and hospitalizations due to decompensated HF. Predicted survival rate were calculated using MAGGIC Risk Calculator and Seattle Heart Failure Model (SHFM). Initially, the Charlson comorbidity index (CCI) was calculated for all patients. Results. Three- and five-year survival rates were 79,7% and 66,1%, respectively, which were significantly higher than predicted by MAGGIC (p=0.02) and SHFM (p=0.01). The median time to the primary endpoint was 1494 days and the annual mortality was 7%. Patients with HF NYHA class III, chronic kidney disease and CCI ≥7 points had worse prognosis (p 1 =0.002, p 2 =0.003, p 3 =0.04 (log-rank test). There was a significant decrease in number of hospitalized pa- tients due to HF decompensated during CCM (p˂0.001) compared with the six-month period before the system implantation. Patients with CCI value ≥ 7 points reached secondary composite endpoint faster (p=0.002 and p=0.004 for three-year and five-year follow-up periods, respectively (log-rank test)). Conclusion . Long-term survival rates of patients with HFrEF II/III (NYHA) receiving CCM and managed on multidisciplinary team were significantly higher than predicted. The heavy comorbidity burden negatively impacts on the clinical course and outcomes of HF patients following CСM implantation. Applying the Charlson index can be useful in a comprehensive assessment of the prognosis and determining the target population for the expensive implantable devices, including CCM, in risk stratification and decision-making algorithms.