Cardiopulmonary transit time measured on dynamic rubidium cardiac PET/CT is a predictor for pulmonary hypertension

Cardiopulmonary transit time (CPTT), the time for blood to circulate from the right to the left ventricle, can be assessed on dynamic Rubidium-82 ([⁸²Rb]) cardiac PET/CT. Given its association with cardiac and pulmonary function, CPTT holds potential as a screening marker for pulmonary hypertension. This study investigated the relationship between CPTT and echocardiographic markers of cardiac function, as well as its association with pulmonary hypertension. In this retrospective single-center study, 111 patients (72 male, 39 female) referred for [⁸²Rb]RbCl-PET/CT and echocardiography within 31 days were included. CPTT, normalized to heart rate (NCPTT), was calculated from peak right and left ventricular [⁸²Rb] activity and examined in relation to patient characteristics and echocardiographic parameters, which were further used to categorize left and right ventricular systolic dysfunction, left ventricular diastolic dysfunction, and signs of elevated pulmonary arterial pressure.

Prolonged NCPTT was significantly associated with lower left ventricular ejection fraction and increased body weight (p < 0.05). NCPTT was significantly associated with left and right ventricular systolic dysfunction (OR = 1.21, 95%CI:1.04-1.42, p < 0.05; OR = 1.18, 95%CI:1.04-1.34, p < 0.01), elevated pulmonary arterial pressure (OR = 1.21, 95%CI:1.02-1.44, p < 0.05), and possible pulmonary hypertension (p < 0.05), but not with left ventricular diastolic dysfunction.

Our findings suggest that NCPTT may serve as a useful additional marker for assessing cardiac function, particularly ejection fraction, and could help in the evaluation of patients with suspected cardiac systolic dysfunction, as well as the detection of pulmonary hypertension.