Distribution of normalized pulmonary transit time per pathology in a population of routine CMR examinations.

ABSTRACT

Pulmonary transit time (PTT), defined as the time taken for a contrast agent bolus to pass from the right ventricle to the left ventricle, is a surrogate for non-invasive assessment of preload. It is used in several imaging modalities pulmonary angiography, echocardiography and cardiac magnetic resonance (CMR). Many recent studies have highlighted the prognostic value of PTT. Therefore, we sought to evaluate PTT in a consecutive cohort of patients undergoing CMR. We retrospectively evaluated PTT normalised for heart rate in 278 patients (66% male, mean age 58 ± 11 years) who underwent CMR between August 2017 and November 2021 with a diagnosis of dilated cardiomyopathy, infarct, hypertrophy, valvular, myocarditis, other pathology or no pathology ("normal"). Normalised pulmonary transit time (nPTT) was higher in men than in women (8.4 ± 1.3 beats vs 7.5 ± 1.1 beats, p = 0.002) in the "normal" group. nPTT was moderately correlated with left ventricular end-diastolic volume (LVEDV) (r2 = 0.19; p < 0.001), left ventricular end-systolic volume (LVESV) (r2 = 0.34; p < 0.001) and left ventricular ejection fraction (LVEF) (r2 = 0.29; p < 0.001). nPTT was significantly higher in patients with dilated cardiomyopathy (11.3 ± 5.4 beats; p < 0.001), infarct (9.5 ± 2.9 beats; p < 0.001) or valvular heart disease (9.5 ± 3.1 beats; p = 0.006) than in patients included in the "normal" group (7.9 ± 1.3 beats). The nPTT is an important marker of pathology. Its value depends on sex and type of pathology, but it is not specific for any type of pathology.