Right ventricular-pulmonary arterial uncoupling in mild-to-moderate asthma

Persistent pulmonary hypertension and resulting right ventricular (RV) failure are highly encountered phenomenon in severe pulmonary diseases. However, in this study, we aimed to examine the effects of mild-to-moderate asthma on RV functions, pulmonary arterial stiffness (PAS), and coupling of RV to the pulmonary artery (PA) in the absence of overt pulmonary hypertension.

We enrolled 53 patients with mild-to-moderate asthma, and 50 healthy control subjects. A comprehensive two dimensional transthoracic echocardiography was performed on each individual. The parameters measuring RV function were all examined. PAS was calculated by dividing maximal frequency shift of pulmonary flow by pulmonary acceleration time. RV-PA coupling was estimated by the tricuspid annular plane systolic excursion (TAPSE) to pulmonary artery systolic pressure (PASP) ratio (TAPSE/PASP).

Baseline demographics, clinical and laboratory parameters of both groups were similar (p > 0.05). Most of conventional echocardiographic parameters measuring RV function were impaired in patients with asthma compared to control subjects. PAS values were significantly higher in the asthma group [24 (21-26) vs. 20 (18-22), p < 0.001], and TAPSE/PASP ratio was significantly lower in the asthma group versus the control group [0.81 ± 0.08 vs. 0.96 ± 0.11, p < 0.001]. Multilinear regression analysis revealed PAS, TAPSE, and PASP as independent predictors of TAPSE/PASP ratio.

Mild-to-moderate asthma was shown to be associated with both subclinical RV dysfunction and increased PAS values. TAPSE/PASP ratio was also markedly decreased, suggesting RV-PA uncoupling even in the absence of overt pulmonary hypertension. PAS referring RV afterload was shown to be an independent predictor of TAPSE/PASP ratio.