Pulmonary hypertension during exercise underlies unexplained exertional dyspnoea in patients with Type 2 diabetes

Aims To compare the cardiac function and pulmonary vascular function during exercise between dyspnoeic and non-dyspnoeic patients with Type 2 diabetes mellitus (T2DM). Methods and results Forty-seven T2DM patients with unexplained dyspnoea and 50 asymptomatic T2DM patients underwent exercise echocardiography combined with ergospirometry. Left ventricular (LV) function [stroke volume, cardiac output (CO), LV ejection fraction, systolic annular velocity (s ')], estimated LV filling pressures (E/e '), mean pulmonary arterial pressures (mPAPs) and mPAP/COslope were assessed at rest, low- and high-intensity exercise with colloid contrast. Groups had similar patient characteristics, glycemic control, stroke volume, CO, LV ejection fraction, and E/e ' (P > 0.05). The dyspnoeic group had significantly lower systolic LV reserve at peak exercise (s ') (P = 0.021) with a significant interaction effect (P < 0.001). The dyspnoeic group also had significantly higher mPAP and mPAP/CO at rest and exercise (P < 0.001) with significant interaction for mPAP (P < 0.009) and insignificant for mPAP/CO (P = 0.385). There was no significant difference in mPAP/COslope between groups (P = 0.706). However, about 61% of dyspnoeic vs. 30% of non-dyspnoeic group had mPAP/COslope > 3 (P = 0.009). The mPAP/COslope negatively predicted V?O-2peak in dyspneic group (beta = -1.86, 95% CI: -2.75, -0.98; multivariate model R-2:0.54). Conclusion Pulmonary hypertension and less LV systolic reserve detected by exercise echocardiography with colloid contrast underlie unexplained exertional dyspnoea and reduced exercise capacity in T2DM.

Automated summary

In patients with Type 2 diabetes mellitus, the dyspnoeic group showed abnormal cardiac and pulmonary vascular function during exercise, including lower LV systolic reserve and higher mean pulmonary arterial pressures. These abnormalities may contribute to exertional dyspnoea and reduced exercise capacity in these patients.