CRT-P or CRT-D? Which parameters can help in selection? (2024)

Background: According to current guidelines CRT-D (cardiac resynchronization therapy with implantable cardioverter defibrillator) is preferred over CRT-P (cardiac resynchronization therapy without implantable cardioverter defibrillator) in patients with chronic systolic heart failure (HF-REF) with NYHA II-III and LVEF (left ventricular ejection fraction) ≤ 35%. However, a certain proportion of patients becomes asymptomatic and/or their LVEF increases above 35% some months after biventricular pacemaker (BiV PM) implantation, and in such cases the indication of ICD no longer exists.

Aim: To quantify the proportion of patients with HF-REF whose LVEF increases above 35% six months after CRT, and to determine parameters, which can predict the lack of such improvement of LVEF.

Patients and methods: 188 pts (82.4% men, mean age: 60.8±11.6 years, ischemic etiology: 38.4%, mean LVEF: 27.8±6.3%, mean NYHA: 2.51±0.87) with CRT (99 pts – CRT-D, 89 pts – CRT-P) followed at our heart failure clinic were included in the study. Baseline (before CRT application) clinical, echocardiographic, ECG and laboratory parameters were analyzed by logistic regression method to assess their power to predict whether LVEF remains below 35%, 6 months after initiation of CRT.

Results: At the time of implantation of BiV PM, according to the indication, every pt had LVEF lower than 35%. Six months after BiV PM implantation 36.8% of patients had LVEF higher than 35%, so they had no indication for ICD at that time. Among investigated parameters left ventricular end-systolic diameter above 55mm (OR: 8.13; CI: 2.19-30.10; p<0.01), systolic blood pressure lower than 110 mmHg (OR: 5.49; CI: 1.31-23.02; p<0.05), ischemic etiology (OR: 3.81; CI: 1.06-13.70; p<0.05), and estimated pulmonary artery systolic pressure higher than 35 mmHg (OR: 3.58; CI: 1.03-12.41; p<0.05) proved to be independent predictors of the lack of an LVEF improvement above 35%. During 6 months after BiV PM implantation no patient died, and appropriate ICD shock was observed only in one patient with CRT-D.

Conclusions: Six months after BiV PM implantation LVEF increases above 35% in more than one-third of patients, as a consequence of the beneficial effects of CRT. In these patients CRT-P implantation would have been enough instead of CRT-D application. Parameters which can predict the lack of LVEF improvement above 35% may play a role in the prediction of non-responderity to CRT as well as in the appropriate selection of CRT-P and CRT-D candidates.