Exercise-induced myocardial T1 increase and right ventricular dysfunction in recreational cyclists: a CMR study.

PURPOSE: Although cardiac troponin I (cTnI) increase following strenuous exercise has been observed, the development of exercise-induced myocardial edema remains unclear. Cardiac magnetic resonance (CMR) native T1/T2 mapping is sensitive to the pathological increase of myocardial water content. Therefore, we evaluated exercise-induced acute myocardial changes in recreational cyclists by incorporating biomarkers, echocardiography and CMR. METHODS: Nineteen male recreational participants (age: 48 ± 5 years) cycled the 'L'étape du tour de France" (EDT) 2021' (175 km, 3600 altimeters). One week before the race, a maximal graded cycling test was conducted to determine individual heart rate (HR) training zones. One day before and 3-6 h post-exercise 3 T CMR and echocardiography were performed to assess myocardial native T1/T2 relaxation times and cardiac function, and blood samples were collected. All participants were asked to cycle 2 h around their anaerobic gas exchange threshold (HR zone 4). RESULTS: Eighteen participants completed the EDT stage in 537 ± 58 min, including 154 ± 61 min of cycling time in HR zone 4. Post-race right ventricular (RV) dysfunction with reduced strain and increased volumes (p < 0.05) and borderline significant left ventricular global longitudinal strain reduction (p = 0.05) were observed. Post-exercise cTnI (0.75 ± 5.1 ng/l to 69.9 ± 41.6 ng/l; p < 0.001) and T1 relaxation times (1133 ± 48 ms to 1182 ± 46 ms, p < 0.001) increased significantly with no significant change in T2 (p = 0.474). cTnI release correlated with increase in T1 relaxation time (p = 0.002; r = 0.703), post-race RV dysfunction (p < 0.05; r = 0.562) and longer cycling in HR zone 4 (p < 0.05; r = 0.607). CONCLUSION: Strenuous exercise causes early post-race cTnI increase, increased T1 relaxation time and RV dysfunction in recreational cyclists, which showed interdependent correlation. The long-term clinical significance of these changes needs further investigation. TRIAL REGISTRATION NUMBERS AND DATE: NCT04940650 06/18/2021. NCT05138003 06/18/2021.

Validation of a Score for the Detection of Subjects with High Risk for Severe High-Altitude Illness.

PURPOSE: A decision tree based on a clinicophysiological score (severe high-altitude illness (SHAI) score) has been developed to detect subjects susceptible to SHAI. We aimed to validate this decision tree, to rationalize the prescription of acetazolamide (ACZ), and to specify the rule for a progressive acclimatization. METHODS: Data were obtained from 641 subjects in 15 European medical centers before and during a sojourn at high altitude. Depending on the value of the SHAI score, advice was given and ACZ was eventually prescribed. The outcome was the occurrence of SHAI at high altitude as a function of the SHAI score, ACZ prescription, and use and fulfillment of the acclimatization rule. RESULTS: The occurrence of SHAI was 22.6%, similar to what was observed 18 yr before (23.7%), whereas life-threatening forms of SHAI (high-altitude pulmonary and cerebral edema) were less frequent (2.6%-0.8%, P = 0.007). The negative predictive value of the decision tree based was 81%, suggesting that the procedure is efficient to detect subjects who will not suffer from SHAI, therefore limiting the use of ACZ. The maximal daily altitude gain that limits the occurrence of SHAI was established at 400 m. The occurrence of SHAI was reduced from 27% to 12% when the recommendations for ACZ use and 400-m daily altitude gain were respected (P < 0.001). CONCLUSIONS: This multicenter study confirmed the interest of the SHAI score in predicting the individual risk for SHAI. The conditions for an optimized acclimatization (400-m rule) were also specified, and we proposed a rational decision tree for the prescription of ACZ, adapted to each individual tolerance to hypoxia.