Exercise training and high‐sensitivity cardiac troponin T in patients with heart failure with reduced ejection fraction

Aims Whether an exercise training intervention is associated with reduction in long‐term high‐sensitivity cardiac troponin T (hs‐cTnT) concentration (a biomarker of subclinical myocardial injury) in patients with heart failure with reduced ejection fraction (HFrEF) is unknown. The aims were to determine (i) the effect of a 12 week endurance exercise training intervention with different training intensities on hs‐cTnT in stable patients with HFrEF (left ventricular ejection fraction ≤ 35%) and (ii) associations between hs‐cTnT and peak oxygen uptake (VO 2peak ). Methods and results In this sub‐study of the SMARTEX‐HF trial originally including 261 patients from nine European centres, 213 eligible patients were included after withdrawals and appropriate exclusions [19% women, mean age 61.2 years (standard deviation: 11.9)], randomized to high‐intensity interval training (HIIT; n  = 77), moderate continuous training (MCT; n  = 63), or a recommendation of regular exercise (RRE; n  = 73). Hs‐cTnT measurements and clinical data acquired before (BL) and after a 12 week exercise training intervention (12 weeks) and at 1 year follow‐up (1 year) were analysed using multivariable mixed models. Baseline hs‐cTnT was above the 99th percentile upper reference limit of 14 ng/L in 35 (48%), 35 (56%), and 49 (64%) patients in the RRE, MCT, and HIIT groups, respectively. Median hs‐cTnT was 16 ng/L at BL, 14 ng/L at 12 weeks, and 14 ng/L at 1 year. Hs‐cTnT was statistically significantly reduced at 12 weeks in a model adjusted for randomization group, centre and VO 2peak , and after further adjustment in the final model that also included age, sex, creatinine concentrations, N‐terminal pro‐brain natriuretic peptide, smoking, and heart failure treatment. The mean reduction from BL to 12 weeks in the final model was 1.1 ng/L (95% confidence interval: 1.0–1.2 ng/L, P  < 0.001), and the reduction was maintained at 1 year with a mean reduction from BL to 1 year of 1.1 ng/L (95% confidence interval: 1.0–1.1 ng/L, P  = 0.025). Randomization group was not associated with hs‐cTnT at any time point (overall test: P  = 0.20, MCT vs. RRE: P  = 0.81, HIIT vs. RRE: P  = 0.095, interaction time × randomization group: P  = 0.88). Independent of time point, higher VO 2peak correlated with lower hs‐cTnT (mean reduction over all time points: 0.2 ng/L per increasing mL·kg −1 ·min −1 , P  = 0.002), without between‐group differences ( P  = 0.19). Conclusions In patients with stable HFrEF, a 12 week exercise intervention was associated with reduced hs‐cTnT in all groups when adjusted for clinical variables. Higher VO 2peak correlated with lower hs‐cTnT, suggesting a positive long‐term effect of increasing VO 2peak on subclinical myocardial injury in HFrEF, independent of training programme.