One-Minute Heart Rate Recovery and Clinical Outcomes in Transthyretin Cardiac Amyloidosis: Incremental Model Fit Beyond Conventional CPET Indices
Antonio Kösters, Nikita Ermolaev, Mahshid Eslami, Leonhard Lichtblau, Lisa Seilinger, Stefanie Pahr, Mariusz Grzeda, Roza Badr EslamAbstract
Aims
To assess the association of one-minute heart rate recovery (HRR1) with clinical outcomes and its incremental contribution to model fit beyond peak VO2 and ventilatory efficiency (VE/VCO2 slope) in transthyretin cardiac amyloidosis (ATTR-CM).
Methods
Consecutive adults with confirmed ATTR-CM undergoing symptom-limited cardiopulmonary exercise testing (CPET) were included in this single-centre observational study. During standardised active recovery at 24 W, HRR1 was defined as peak heart rate minus heart rate exactly 60 seconds after exercise. Cox proportional-hazards models evaluated all-cause mortality and the composite of mortality or first heart-failure hospitalisation. Principal models adjusted for age, sex, peak VO2 and VE/VCO2 slope; NT-proBNP and National Amyloidosis Centre (NAC) stage were examined separately.
Results
Of 161 baseline patients, 11 with unverifiable heart-rate measurements were excluded, and exact HRR1 was available in 110. Mortality analysis included 105 patients with 33 deaths; composite-outcome analysis included 107 patients with 51 events. Median HRR1 was 15.5 bpm. In conventional CPET-adjusted models, each 10-bpm greater HRR1 was associated with lower hazards of mortality (hazard ratio [HR] 0.65, 95% confidence interval [CI] 0.44–0.95; P = 0.028) and the composite outcome (HR 0.74, 95% CI 0.57–0.97; P = 0.029). Adding HRR1 improved model fit (likelihood-ratio P = 0.017 and P = 0.021, respectively); apparent C-indices increased from 0.770 to 0.795 for mortality and from 0.695 to 0.699 for the composite outcome. Associations were non-significant after separate adjustment for NT-proBNP or NAC stage.
Conclusion
HRR1 remained associated with outcomes after CPET adjustment and improved model fit. Discrimination gains were modest; value beyond biomarker staging was unproven.