Predictors of patient-perceived functional improvement after cardiac resynchronization therapy: a real-world multi-dimensional analysis of clinical, imaging, and ECG predictors.

Introduction: Up to one-third of appropriately selected patients undergoing cardiac resynchronization therapy (CRT) fail to achieve meaningful clinical benefit despite fulfilling guidelines' criteria. Traditional CRT response definitions [left ventricular (LV) end-systolic volume (ESV), ejection fraction (EF), and QRS duration] frequently diverge and occasionally fail to reflect patient-perceived clinical improvement. Objective: To identify predictors for patient-perceived functional improvement after CRT, incorporating various clinical, biochemical, electrocardiographic (ECG), and imaging variables. Functional improvement was defined as the changes in New York Heart Association (NYHA) functional class 6-9 months after CRT implantation. Methods: This retrospective single-center study included 97 heart failure (HF) patients meeting guideline-based CRT indications. Patients were categorized according to ≥1 NYHA class improvement at 6-9 months. Baseline and follow-up clinical, biochemical, ECG, echocardiographic, and cardiac magnetic resonance (CMR) parameters were compared between groups. Predictors of functional improvement were assessed using univariate and multivariate logistic regression. Results: Sixty-eight patients (70%) achieved ≥1 NYHA class improvement. At baseline, the non-improved group was characterized by higher NT-proBNP and creatinine levels, longer PR and shorter QTc intervals, and worse LV and RV global longitudinal strain (GLS) on CMR. At follow-up, NT-proBNP remained elevated in the non-improved group. Traditional CRT response criteria were more frequently met in the improved compared to the non-improved group (>15% LV ESV reduction: 94.7% vs. 5.3%, >10% LV EF improvement: 98.1% vs. 1.9%, and >20 ms QRS shortening: 86.2% vs. 13.8%); but none independently predicted functional improvement in multivariate analysis. Independent predictors for ≥1 NYHA class improvement included baseline renal function (OR 1.19, 95% CI 1.00-1.39, Conclusion: Functional improvement after CRT is best predicted by multi-dimensional assessment incorporating clinical, biochemical, and imaging parameters. In addition to the traditional response definitions, renal function, LV GLS, and LV diastolic indices were independently associated with a better patient-perceived functional improvement after CRT. Incorporating these factors into CRT eligibility and prognostication may enhance patient selection and improve outcomes.