Prognostic value of novel cardiovascular magnetic resonance transit times beyond the pulmonary circulation in patients with ventricular dysfunction.

Objectives: To evaluate the prognostic value of transit time (TT) assessment in the systemic circulation and organ perfusion in patients with ventricular dysfunction (VD). The primary endpoint was defined as death, heart failure admission, or ventricular arrhythmias, and the secondary endpoint was worsening renal function.

Methods: A retrospective study on 139 patients who underwent cardiac magnetic resonance for VD evaluation and 50 controls. TT was measured as peak-to-peak time in signal intensity over time curves obtained at different stages of circulation (right cavities, left cavities, aorta, and peripheral organs) from first-pass perfusion images. Outcomes were monitored over a median follow-up of 15 months.

Results: A total of 139 patients were included (84% male, age 63 [57-70] years). Patients exhibited significantly prolonged TT compared to controls, with in-patients showing longer times than outpatients. Among the 29 patients reaching the primary endpoint, both PTT and STT were significantly prolonged (PTT: 9.75 s vs 13.4 s, p < 0.01; STT: 4.77 s vs 7.00 s, p < 0.01). Concurrent prolongation of PTT (> 10 s) and STT (> 5 s) was associated with a higher event probability (42.3%), compared to isolated abnormalities (6.3% for PTT, 6.7% for STT). Multivariate analysis revealed that combined PTT and STT alteration independently predicted the combined endpoint (HR IC 95%: 8.685 (2.415-31.236), p = 0.001). Prolonged RPT was independently associated with renal function deterioration (OR IC 95%: 1.129 (1.015-1.256), p = 0.024).

Conclusions: Evaluation of TT beyond pulmonary circulation provides prognostic insights into VD. Simultaneous assessment of PTT and STT enhances specificity compared to isolated PTT evaluation, predicting combined adverse events. RPT is independently associated with renal impairment.

Clinical Relevance Statement: For the first time, it is described that transit time can be evaluated in systemic circulation and in peripheral organs and that this assessment can be easily made from conventional CMR perfusion images and holds significant prognostic value.

Key Points: Pulmonary transit time is a valuable hemodynamic parameter; systemic transit time may also be valuable. Transit time can be measured in the systemic circulation, and is longer in patients with ventricular dysfunction. Systemic transit time assessed by magnetic resonance imaging identifies patients with ventricular dysfunction who will experience events during follow-up.