Diagnostic Yield of Customized Exercise Provocation Following Routine Testing.

Clinical guidelines advocate for customization of exercise testing to address patient-specific diagnostic goals, including reproduction of presenting exertional symptoms. However, the diagnostic yield of adding customized exercise testing to graded exercise in patients presenting with exertional complaints has not been rigorously examined and is the focus of this study. Using prospectively collected data, we analyzed the diagnostic yield of customized additional exercise provocation following inconclusive graded exercise test with measurement of gas exchange. Additional testing was defined as "positive" if it revealed a clinically-actionable diagnosis related to the chief complaint or reproduced symptoms in the absence of an explanatory diagnosis or pathology. Of 1,110 patients who completed a graded test, 122 (11%) symptomatic patients underwent additional customized exercise testing (e.g., sprint intervals and race simulations). Compared with those who did not undergo additional testing, this group was younger (29 [interquartile range 19 to 45] vs 46 [25 to 58] year old) and disproportionately female (43% vs 27%). Presenting symptoms included palpitations (46%), lightheadedness/syncope (25%), chest pain (14%), dyspnea (11%), and exertional intolerance (3%). Additional testing was "positive" in 48 of 122 (39%) of patients by revealing a clinically actionable diagnosis in 26 of 48 (54%) or reproducing symptoms without an explanatory diagnosis in 22 of 48 (46%). In conclusion, while patient-centered customization of exercise testing is suggested by clinical guidelines, these data are the first to demonstrate that the selective addition of customized exercise provocation following inconclusive graded exercise testing improves the diagnostic yield of exercise assessment.

Cardiovascular response to prescribed detraining among recreational athletes.

Exercise-induced cardiac remodeling (EICR) and the attendant myocardial adaptations characteristic of the athlete's heart may regress during periods of exercise reduction or abstinence. The time course and mechanisms underlying this reverse remodeling, specifically the impact of concomitant plasma volume (PV) contraction on cardiac chamber size, remain incompletely understood. We therefore studied recreational runners ( n = 21, age 34 ± 7 yr; 48% male) who completed an 18-wk training program (~7 h/wk) culminating in the 2016 Boston Marathon after which total exercise exposure was confined to <2 h/wk (no single session >1 h) for 8 wk. Cardiac structure and function, exercise capacity, and PV were assessed at peak fitness (10-14 days before) and at 4 wk and 8 wk postmarathon. Mixed linear modeling adjusting for age, sex, V̇o2peak, and marathon finish time was used to compare data across time points. Physiological detraining was evidenced by serial reductions in treadmill performance. Two distinct phases of myocardial remodeling and hematological adaptation were observed. After 4 wk of detraining, there were significant reductions in PV (Δ -6.0%, P < 0.01), left ventricular (LV) wall thickness (Δ -8.1%, <0.05), LV mass (Δ -10.3%, P < 0.001), and right atrial area (Δ -8.2%, P < 0.001). After 8 wk of detraining, there was a significant reduction in right ventricle chamber size (end-diastolic area Δ = -8.0%, P < 0.05) without further concomitant reductions in PV or LV wall thickness. Abrupt reductions in exercise training stimulus result in a structure-specific time course of reverse cardiac remodeling that occurs largely independently of PV contraction. NEW & NOTEWORTHY Significant reverse cardiac remodeling, previously documented among competitive athletes, extends to recreational runners and occurs with a distinct time course. Initial reductions in plasma volume and left ventricular (LV) mass, driven by reductions in wall thickness, are followed by contraction of the right ventricle. Consistent with data from competitive athletes, LV chamber volumes appear less responsive to detraining and may be a more permanent adaptation to sport.