Does the lack of left ventricular reverse remodeling always mean non-response to cardiac resynchronization therapy?

Abstract

Aim. To evaluate clinical, morphological, functional features and mortality level in patients with different value of left ventricular reverse remodeling after cardiac resynchronization therapy (CRT). Materials and methods. The study enrolled 112 patients (mean age 54.6±9.9 years, 83.5% men) with left ventricular ejection fraction (LVEF) 35%, NYHA functional class II-IV. We enrolled patients with QRS width >120 ms or QRS <120 ms + 3 parameters of mechanical dyssynchrony by echocardiography. Clinical, electrocardiographic and echocardiographic parameters were evaluated at baseline, 1, 3 months and each 6 months after implantation. Three patients with increase of left ventricular end-systolic volume (LVESV) were excluded from prospective trial due to lack of full follow-up data. According to the best decrease of LVESV (mean follow-up period 34.8±16.7 months) patients were classified as non-progressors (n=18; decrease in LVESV <15%), responders (n=41; decrease in LVESV 15-29%) and superresponders (SR) (n=50; reduction in LVESV ≥30%). Results. At baseline groups were matched for main clinical characteristics, the proportion of patients with atrial fibrillation, width of the QRS complex, and the presence of left bundle-branch block. Echocardiographic parameters didn't differ between the groups. All groups demonstrated significant reverse remodeling of the left ventricle, increase in LVEF, increase in 6-minute walking distance. SR demonstrated the best improvement of clinical and functional parameters after CRT. However, improvement in LVEF, LVESV, NYHA functional class between responders and non-progressors were found similar. Dynamics of these parameters were comparable. The survival rates were 100% in SR, 80% in responders and 88.9% in non-progressors (Log-Rank test p=0.001). Survival rates in responders and non-progressors didn't differ significantly (Log-Rank test p=0.150). Conclusion. Patients with reduction in LVESV less than 15% demonstrate improvement in clinical status, LVEF and survival rates compared to subjects with reduction in LVESV 15-29%. Non-progressors demonstrate similar survival as responders in long-term period. Taking into account the natural course of CHF functional stabilisation and absence of CHF progression in patients with lack of left ventricular reverse remodelling is a variant of good response and these patients should not be identified as non-responders.