Are you short of breath? comparing functional capacity using new york heart association class and cardiopulmonary exercise testing

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background New York Heart Association (NYHA) scale is used to assess symptom severity in heart failure patients. Despite it being used routinely in clinical practice, it is heavily dependent on patient and physician subjectivity. Cardiopulmonary exercise testing (CPET) provides a potentially more objective and reproducible measure of functional capacity. Purpose To assess functional capacity in NYHA 1 versus NYHA 2-4 patients. Investigators also wanted to explore any relationship between NYHA class and CPET variables in heart failure patients. Method A retrospective analysis of patients who underwent CPET between 2021 & 2022 was performed. The patients were grouped according to NYHA score and ejection fraction (EF). A separate subgroup analysis was carried out in NYHA 1, comparing patients with an EF < 35% and EF > 35%. Results A total of 160 patients were included, a dominant male (81.3%) Caucasian (95%) population with an average age of 53.9 years. 13.8% had an EF <35%. 51.9% had ischaemic cardiomyopathy. 103 (64.4%) patients had a NYHA score of 1, the rest had a NYHA score of 2-3. There was no significant difference between demographic parameters and co-morbidities between the groups. Figure 1 depicts CPET parameters comparing NYHA 1 vs NYHA 2-4 groups. VO2 MAX and % VO2 Max Predicted were significantly higher in NYHA 1 vs NYHA 2-4 (Figure 1). NT-proBNP levels were lower in the NYHA 1 group (378 pg/mL vs 850 pg/mL, p=0.023). Further analysis of the NYHA Class 1 group, comparing EF< 35% and >35% was carried out. It was discovered that despite being assigned the same NYHA Class, the EF <35% group had significantly lower VO2 max, % predicted VO2 max and VE/VCO2. EF was an important predictor of CPET performance in NYHA 1 patients. Those with an EF <35% had a lower VO2 max (p=0.001), low % VO2 Max predicted (p=0.005) and higher VE/VCO2 (p=0.002). NT-proBNP was also higher in this subgroup (p=0.047). Conclusion NYHA is an effective tool at assessing symptom severity in heart failure patients, albeit subjectively. CPET is particularly useful in NYHA 1 patients as it can give an objective assessment of functional capacity in these asymptomatic individuals. Future studies should explore the possible role of CPET in determining suitability for advanced heart failure therapies in NYHA 1 heart failure patients.