Prognostic Value of Pulmonary Transit Time and Pulmonary Blood Volume Estimation Using Myocardial Perfusion CMR

Abstract

Objectives The purpose of this study was to explore the prognostic significance of PTT and PBVi using an automated, inline method of estimation using CMR. Background Pulmonary transit time (PTT) and pulmonary blood volume index (PBVi) (the product of PTT and cardiac index), are quantitative biomarkers of cardiopulmonary status. The development of cardiovascular magnetic resonance (CMR) quantitative perfusion mapping permits their automated derivation, facilitating clinical adoption. Methods In this retrospective 2-center study of patients referred for clinical myocardial perfusion assessment using CMR, analysis of right and left ventricular cavity arterial input function curves from first pass perfusion was performed automatically (incorporating artificial intelligence techniques), allowing estimation of PTT and subsequent derivation of PBVi. Association with major adverse cardiovascular events (MACE) and all-cause mortality were evaluated using Cox proportional hazard models, after adjusting for comorbidities and CMR parameters. Results A total of 985 patients (67% men, median age 62 years [interquartile range (IQR): 52 to 71 years]) were included, with median left ventricular ejection fraction (LVEF) of 62% (IQR: 54% to 69%). PTT increased with age, male sex, atrial fibrillation, and left atrial area, and reduced with LVEF, heart rate, diabetes, and hypertension (model r 2 = 0.57). Over a median follow-up period of 28.6 months (IQR: 22.6 to 35.7 months), MACE occurred in 61 (6.2%) patients. After adjusting for prognostic factors, both PTT and PBVi independently predicted MACE, but not all-cause mortality. There was no association between cardiac index and MACE. For every 1 × SD (2.39-s) increase in PTT, the adjusted hazard ratio for MACE was 1.43 (95% confidence interval [CI]: 1.10 to 1.85; p = 0.007). The adjusted hazard ratio for 1 × SD (118 ml/m 2 ) increase in PBVi was 1.42 (95% CI: 1.13 to 1.78; p = 0.002). Conclusions Pulmonary transit time (and its derived parameter pulmonary blood volume index), measured automatically without user interaction as part of CMR perfusion mapping, independently predicted adverse cardiovascular outcomes. These biomarkers may offer additional insights into cardiopulmonary function beyond conventional predictors including ejection fraction.

Prognostic value of pulmonary transit time by cardiac magnetic resonance imaging in ST-elevation myocardial infarction

“…Previous studies have evaluated the prognostic value of PBVI in heart failure, in patients referred for perfusion CMR or after Ross procedure [ 5 , 10 , 12 ]. Although patients with MACE exhibited slightly larger PBVI in our cohort, differences did not reach statistical significance and PBVI was not an independent predictor of MACE.…”

“…Magnetic resonance imaging has been validated for pulmonary blood volume evaluation based on contrast bolus transit in a phantom [ 11 ]. Recently, a large study in patients with known or suspected coronary artery disease who were referred for perfusion cardiac magnetic resonance (CMR) imaging found an association between pTT at rest and nonfatal major adverse cardiovascular events (MACE) independent of conventional risk parameters [ 12 ]. However, CMR data on pTT early after ST-elevation myocardial infarction (STEMI) as well as in the follow-up are lacking so far.…”

Direct cardiovascular complications and indirect collateral damage during the COVID-19 pandemic

“…On the contrary, Joy et al. investigated cardiovascular changes in a cohort of 74 patients with a mild clinical course of COVID-19 compared with 75 seronegative control patients 6 months after infection [ 53 ]. Thorough analysis of cardiovascular biomarkers and cardiac magnetic resonance imaging did not reveal any long-term cardiovascular abnormalities in COVID-19 patients with only mild symptoms [ 53 ].…”

Third-Generation Cardiovascular Phantom

“…17,18,38 Transit times from right ventricle to left ventricle were estimated from literature between 8 and 12 seconds, with phantom measurement of 12.0 ± 0.2 seconds. 17,18,38,39 From left ICA to left IJV, ranges estimated from literature were 7 to 10 seconds, whereas phantom measurements showed 7.7 ± 0.4 seconds. 40 Finally, transit times from aortic arch to aortic bifurcation were estimated from literature between 2.4 and 4 seconds and measured in the phantom at 2.9 ± 0.1 seconds.…”

“…Contrast media arrival in the literature between antecubital vein and right ventricle was estimated between 10 and 16 seconds, with empirical phantom measurement of 13.1 ± 0.3 seconds 17,18,38 . Transit times from right ventricle to left ventricle were estimated from literature between 8 and 12 seconds, with phantom measurement of 12.0 ± 0.2 seconds 17,18,38,39 . From left ICA to left IJV, ranges estimated from literature were 7 to 10 seconds, whereas phantom measurements showed 7.7 ± 0.4 seconds 40 .…”