Cardiac Resynchronization Therapy: Mechanisms, Indications, and Clinical Outcomes in Heart Failure Patients in a Resource-Constrained Setting

Abstract

Objectives: To evaluate the mechanisms, indications, and clinical outcomes of cardiac resynchronization therapy (CRT) in patients with heart failure treated at Hayatabad Medical Complex, Peshawar. Methodology: This retrospective study analyzed data from 100 patients who underwent CRT implantation between January 2015 and September 2024. Eligible patients had heart failure with reduced ejection fraction (LVEF ≤35%), left bundle branch block (LBBB), QRS duration ≥150 ms, and NYHA class II–IV symptoms despite optimized medical therapy. Demographic, clinical, and echocardiographic data were assessed. CRT response was defined as a ≥15% reduction in left ventricular end-systolic volume (LVESV) at six months. Statistical analysis was conducted using SPSS Version 26; one-way ANOVA and chi-square tests were applied with a significance level set at p<0.05. Results: The cohort comprised 60% males, with a mean age of 58.6 ± 11.2 years. The mean baseline LVEF was 28.3 ± 7.4%, and mean QRS duration was 167.4 ± 10.2 ms. Overall, 65% of patients responded to CRT, including 10% who were categorized as super-responders. Non-responders accounted for 25% of the cohort. Responders showed significant reductions in LVESV (180.2 ± 32.1 ml) compared to non-responders (210.5 ± 28.3 ml, p=0.002). Imaging-guided lead placement significantly improved response rates (40 responders vs. 5 non-responders; p=0.004). Hospitalization rates for heart failure exacerbation were significantly lower among responders (mean = 0.8) than non-responders (mean=2.5; p<0.01). Conclusion: CRT significantly enhances cardiac function and reduces hospitalization rates, particularly when guided by imaging for optimal lead placement. These findings underscore the potential of CRT to transform heart failure care, even in resource-limited healthcare settings.