Unexplained exercise-related dyspnea in type 2 diabetes predicts pulmonary arterial hypertension during exercise

Abstract

Purpose: To evaluate whether type 2 diabetes mellitus (T2DM) patients who suffer from unexplained exercise-induced dyspnea display cardiac dysfunction during exercise. Background: Patients with type 2 diabetes mellitus (T2DM) frequently suffer from unexplained dyspnea. It is not fully understood whether these patients have a worse exercise capacity and cardiac dysfunction than non-dyspneic patients. If so, it would be clinically relevant to evaluate cardiac function in T2DM patients with unexplained dyspnea and initiate treatment accordingly. Methods: 47 T2DM patients with unexplained dyspnea and 50 asymptomatic T2DM patients underwent echocardiography with simultaneous cardiopulmonary exercise testing (CPETecho). Left ventricular (LV) function (cardiac output, LV ejection fraction, stroke volume), estimated LV filling pressures (E/e') and mean pulmonary artery pressures (mPAP) were assessed at rest, low- and high-intensity exercise by using colloid contrast. Breath-by-breath analyses were used to monitor exercise intensity and evaluate exercise capacity (V O2peak). Results: The groups had similar characteristics and glycemic control (p>0.05). LV function and E/e' were similar between groups during all stages of exercise (p>0.05). However, mPAP increased disproportionally (mPAP/CO > 3) during exercise in 62% of the patients with dyspnea. The mPAP/CO slope was significantly steeper in the patients with, as opposed to without dyspnea (Pinteraction=0.013). Moreover, a steeper mPAP/cardiac output slope (β= -1.86, 95% CI -2.75, -0.98) was an independent predictor of lower VO2peak (multivariate model R2:0.54). Conclusion: In T2DM patients with unexplained exertional dyspnea, simultaneous cardiopulmonary exercise testing and echocardiography frequently reveal a reduced exercise capacity associated with exercise-induced pulmonary arterial hypertension. Dyspneic T2DM patients possibly have early left atrial and LV diastolic dysfunction. Timely preventive and therapeutic interventions may improve clinical outcomes in these patients. (Table Presented).