Introduction: Heart failure (HF) is a major cause of morbidity and mortality. High-intensity interval training (HIIT) has been proposed to optimize cardiac function, but its long-term effects on heart function, symptom burden, and survival in HF patients remain poorly understood. This study examines the effects of long-term HIIT in individuals with HF.

Methods: This longitudinal observational study was conducted at the cardiac department of Pakistan Institute of Medical Sciences (PIMS), Islamabad, from July 2024 to January 2025. Using purposive non-probability sampling, 158 HF patients aged ≥30 years were recruited. Outcomes—Kansas City Cardiomyopathy Questionnaire (KCCQ-12), Duke Activity Status Index (DASI), and New York Heart Association (NYHA) classification—were assessed at baseline, three months, and six months. Statistical analysis (SPSS v26) included repeated-measures ANOVA, Pearson correlation, and multiple linear regression.

Results: Among 158 participants (71.0% men, 29.0% women; mean age 56.3 ± 12.4 years), KCCQ-12 and DASI scores significantly improved (p < 0.01), while NYHA classification worsened (p < 0.001). Higher HIIT levels correlated with improved functional capacity and quality of life (DASI: r = 0.392; KCCQ-12: r = 0.215, both p < 0.01) and reduced symptom severity (NYHA: r = -0.265, p < 0.01). HIIT, age, gender, and comorbidities were key predictors of outcomes, with women reporting better results and men showing worse symptom indicators.

Conclusion: Over six months, repeated assessment using the KCCQ-12, DASI, and NYHA classification showed that higher HIIT participation was associated with improved functional capacity, quality of life, and reduced heart failure symptom severity. These findings were supported by repeated-measures ANOVA, correlation, and regression analyses. Individually tailored HIIT may therefore be a useful addition to standard heart failure management.

Dr Mohamed A. M. Imam is an internal medicine doctor at Scarborough Hospital, United Kingdom. He contributed to data interpretation, drafting and critical review for the published HIIT heart failure study. He was also involved in multiple case studies. He aims to pursue cardiology subspecialty training and combine patient care with research and education.