Associations of Cardiac myosin binding protein C to Troponin I in patients with chronic heart failure during exercise. A substudy of the SMARTEX-HF trial

Abstract Aim Cardiac myosin binding protein C (cMyC) has shown promise being more sensitive than cardiac troponins, rising faster after myocardial infarction[i]. Its association to hs-cTnI in heart failure patients during physical activity is not known. The aim of this study was to assess the association between a novel biomarker: cMyC and the clinically used high sensitivity cardiac Troponin I (hs-cTnI) during a 12-week exercise training program in patients with chronic symptomatic heart failure with reduced ejection fraction (HFrEF). The changes of biomarkers in plasma levels in an intervention group, performing structured exercise programs, were compared to those in a control group, instructed to perform regular recommended exercise (RRE) according to current guidelines. Methods and results This was a post hoc analysis of the SMARTEX-HF trial in 215 patients with symptomatic heart failure (HF) with Left Ventricular Ejection Fraction (LVEF) <35% and NYHA II-III. The patients were randomly assigned to High Intensity Interval Training (HIIT, n=77), Moderate Continuous Training (MCT, n=65) or RRE, (n=73) for 12 weeks. Measurements and clinical data were acquired before and after the 12-week intervention. In 191 patients, plasma was available for hs-cTnI testing and in 189 patients plasma was available for cMyC testing. Due to the lack of a normal distribution, the values were log transformed. There was a significant association of change in log hs-cTnI and change in log cMyC (Pearson correlation R=0.52 (95% CI 0.37- 0.66) p<0.001) (Figure 1). For any 10% increase in cMyC level, the ratio of the hs-cTnI level increased with approximately 5% (Figure 2). There was no association between the levels of cMyC at baseline and change in hs-cTnI at 12 weeks. Conclusion Changes in levels of the novel biomarker cMyC was significantly associated with hs-cTnI plasma levels in patients with symptomatic chronic HFrEF during a structured 12 week exercise training program. Being more sensitive, it may indicate a role as a future marker of subclinical myocardial damage.Models with adjustmentsMarginal effect at the mean