Plasma catecholamines in patients undergoing invasive cardiopulmonary exercise test for exercise intolerance.

Background: Invasive cardiopulmonary exercise testing (iCPET) combines traditional cardiopulmonary exercise testing with invasive hemodynamic measurements to assess exercise intolerance, which can be caused by preload insufficiency (PI), characterized by low ventricular filling pressures and reduced cardiac output during exertion. We hypothesize that plasma catecholamine levels at rest and during exercise correlate with hemodynamic parameters in PI.

Methods: We included adult patients who underwent iCPET for exercise intolerance and had plasma catecholamines measured at rest and peak exercise.

Results: Among 84 patients, PI was identified in 57 (67.8 %). Compared to patients without PI, those with PI were younger [median (IQR) 37 (28, 46) vs 47 (39,55) years, p = 0.005] and had lower workload at peak exercise [81 (66, 96) vs 95 (83.5, 110.50) Watts, p = 0.006]. Patients with PI had higher heart rates at rest and peak exercise [87 (78, 97) vs 79 (74, 87) bpm, p = 0.04; and 167 (154, 183) vs 156 (136, 168) bpm, p = 0.01, respectively]. In all patients, epinephrine and norepinephrine at peak exercise directly correlated with peak workload (r:0.41, p < 0.001 and r:0.47, p < 0.001, respectively). Resting epinephrine was higher in patients with PI [136 (60, 210) vs 77 (41, 110) pg/mL, p = 0.02]. There was no significant difference in the change in catecholamines from rest to peak exercise between patients with or without PI.

Conclusion: PI patients exhibited elevated heart rate and epinephrine at rest, indicating increased sympathetic activity. We did not find strong associations between catecholamines and cardiac filling pressures, suggesting that catecholamine levels are predominantly influenced by peak workload.