Exercise Echocardiography for mPAP/CO Slope Estimation

Abstract

We read with interest the paper by Gargani et al 1 on the prognostic implications of exercise echocardiog-raphy of the right ventricle and pulmonary circulation. The value of exercise echocardiography for assessing the mean pulmonary artery pressure over cardiac output (mPAP/CO) slope has been a source of conjecture for many years. Particularly, its accuracy and feasibility have been debated, and so far, invasive determination of pulmonary pressures is typically deemed necessary for diagnosing exercise-induced pulmonary hypertension. However, the current study challenges this concept by elegantly demonstrating that noninvasive determination of the mPAP/CO slope, irrespective of its relation to invasive pressures, does provide major diagnostic and prog-nostic information. Acceptable feasibility is another essential requirement for the mPAP/CO slope to become widely adopted in daily practice. Although information regarding feasibility is not provided in the paper, based on the data provided, we could infer that the mPAP/CO slope was obtained in only 720 of 1,356 patients with survival data available. Limited feasibility of mPAP/CO slope estimation was also reported by a previous study, in which tricuspid regurgitation gradients could only be obtained during exercise in 34% of patients. 2 In our experience, the accuracy and feasibility of noninvasive mPAP/CO slope determination can be improved substantially by the use of FI GURE 1 Pulmonary Artery Pressure Measurement Using Colloid Enhancement of the TR Signal Agitated colloid administration (white arrow) improves exercise pressure estimation in a patient without a detectable TR signal. The dotted yellow line represents the echocardiographic estimation of right ventricular systolic pressure. TR ¼ tricuspid regurgitation.