Changes in cardiac function following a speed ascent to the top of Europe at 4808m.

Abstract

Both prolonged exercise and acute high-altitude exposure are known to induce cardiac changes. We sought to describe the cardiac responses to speed climbing at high-altitude, including left ventricular (LV) performance assessment using the myocardial work index (MWI), a new index derived from 2D speckle tracking echocardiography (STE). Eleven elite alpinists (9 males, age: 26 ± 4years) were evaluated before and immediately after a speed ascent of the Mont-Blanc (4808m) by echocardiography using conventional measurements as well as STE and MWI computation with derivate parameters as global work efficiency (GWE) or global wasted work (GWW). Athletes performed a long-duration (8h 58min ± 60min) and intense (78 ± 4% of maximal heart rate) ascent under gradual hypoxic conditions (minimal SpO2 at 4808m: 71 ± 4%). Hypoxic exercise-induced cardiac fatigue was observed post-ascent with a change in right ventricular (RV) and LV systolic function (RV fractional area change: -20 ± 23%, p = 0.01; LV global longitudinal strain change: -8 ± 9%, p = 0.02), as well as LV geometry and RV-LV interaction alterations with emergence of a D-shape septum in 5/11 (46%) participants associated with RV pressure overload (mean pulmonary arterial pressure change: + 55 ± 20%, p < 0.001). Both MWI and GWE were reduced post-ascent (-21 ± 16%, p = 0.004 and -4 ± 4%, p = 0.007, respectively). Relative decrease in MWI and GWE were inversely correlated with increase in GWW (r = -0.86, p = 0.003 and r = -0.97, p < 0.001, respectively). Prolonged high-altitude speed climbing in elite climbers is associated with RV and LV function changes with a major interaction alteration. MWI, assessing the myocardial performance, could be a new tool for evaluating LV exercise-induced cardiac fatigue.