High altitude exposure, high-sensitivity cardiac troponin and biventricular cardiac function

Background: It has been consistently shown that heavy exercise leads to cardiac troponin (cTn) release and variable changes in post-exercise cardiac function. However its relationship to symptoms of acute mountain sickness (AMS) severity and exercise at significant (>4300m) and increasing high altitude (HA) has not been investigated. Purpose/study design: Transthoracic echocardiograms, hs-cTnT and Lake-Louis AMS scores were measured at rest at 1300m then repeated post-exercise and 12 hours later after progressive trekking to 3440 m, 4270m and at 5150m on 19 healthy subjects aged 35.4±8.3 years (52.6% males). Results: There was a significant and detectable increase in post-exercise hs-cTnT with increasing exercise (29.4% at 3440m, 15.8% at 4270m and 68.8% at 5150m; p=0.02). Compared with baseline, HA to 5150m led to a significant rise in AMS scores (0.1±0.3 vs 3.0±3.2; p<0.001) pulmonary artery systolic pressure ([PASP] 23.7±3.8 vs 37.9±11.7 mmHg: p<0.001), cardiac output (CO; 5.2±1.2 vs 7.5±1.3 l/minute; p<0.001) and a fall in SpO2 (96.1± vs 77.4±12.0%; p<0.001). There was no change in stroke volume (75.6± vs 77.3±12.3ml; p=0.10) or estimated filling pressures (E/E') of the left (5.9±1.1 vs 6.3±1.0; p=0.50) and right ventricles (4.5±1.5 vs 4.6±1.1; p=0.4). On multivariate analysis increasing CO (β-0.50, CI 0.024 to 0.98; p=0.040) and PASP (β0.07, 0.001 to 0.13; p=0.04) and decreasing SpO2 (β-0.07; -0.1 to 0.007; p=0.03) were the only independent predictors of increasing cTnT levels (overall R2=0.24; p=0.0004). Conclusions: Moderate intensity exercise at significant HA influences the post-exercise increase in hs-cTnT without overt deleterious effects on cardiac function.