Methods: Prospective study in a cohort of 108P submitted to cardiac resynchronization therapy (CRT), with an ICD in a primary prevention strategy. All P performed cardiac scintigraphy with 123 metaiodo-benzylguanidine in the 48h previous to CRT implant to assess cardiac ANS dysfunction. We considered cardiac ANS dysfunction parameters of Early and Late "heart to mediastinum" rate – HMR - below 1,5 or a washout rate (WR) above 30%. Afterwards, P were randomized to perform a phase 2 cardiac rehabilitation program (30 programed and surveyed sessions) or no rehabilitation. We assessed the medium (3months) to long-term (2 years) occurrence of VT/VF by the interrogation of the CRT device.
Results: There were 67,9% male, with 68,1±9,9 years, and a mean LV ejection fraction of 27±7%, with ischemic etiology in 33,3% and diabetes in 38,9%. Sixty three P (57,8%) were in class III of NYHA and 73% on beta blockers. There were no significant differences between basal characteristics of the 2 groups, namely the occurrence of cardiac ANS (early HMR: p=0,810, late HMR: p=1,0 and WR: p=1,0). The rehabilitation group had a higher rate of previous cardiac surgery (p=0,023). During a follow-up of 630,8 ± 309,7 days, 16P (14,8%) had VT/VF with appropriate treatment via ICD. The occurrence of VT/VF was higher in the cohort of P with cardiac ANS dysfunction, as assessed by the early HMR (p=0,034). P with baseline cardiac ANS dysfunction that did not underwent cardiac rehabilitation were at higher risk of VT/VF (Odds Ratio 4,38; p=0,035), whereas the occurrence of VT/VF was similar in P that completed the cardiac rehabilitation program compared to P without cardiac ANS dysfunction (p=0,597).
Conclusions: HF is associated with a high incidence of cardiac ANS dysfunction. Cardiac rehabilitation seems to modulate ANS in these population and contribute to reduce the incidence of VT/VF.