Congestion quantified as pulmonary blood volume using CMR normalizes after guideline-directed treatment in newly diagnosed heart failure

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Abstract
Background: Pulmonary congestion in heart failure (HF) is challenging to quantify. Recent advances in cardiovascular magnetic resonance (CMR) using routine clinical perfusion scans make it possible to calculate the pulmonary blood volume indexed to body surface area (PBVi) as a prognostic marker of congestion. The aims were to assess if PBVi normalizes after onset of treatment and if PBVi differs in different HF subtypes compared to healthy controls. Methods: In this prospective cohort study, a total of 115 subjects (22 healthy controls, 93 HF patients of which 19 newly diagnosed) underwent CMR at 1.5T. PBVi was calculated as the transit time for a contrast bolus from the right to the left side of the heart during a perfusion scan, multiplied by the cardiac output from 2D aortic flow. Results: Patients with newly diagnosed HF showed signs of pulmonary congestion in terms of an increased PBVi compared to controls (394 vs 302 ml/m2 p = 0·004). After treatment, PBVi normalized to similar levels as controls (296 ml/m2, p > 0·99). There were no differences in PBVi between controls and chronic out-patients with preserved (HFpEF, n = 19, p > 0·999), mildly reduced (HFmrEF, n = 24, p > 0·999) or reduced ejection fraction (HFrEF, n = 31, p = 0·146). Conclusion: This proof-of-concept study demonstrates for the first time that non-invasive PBVi normalizes following initiation of guideline-directed medical therapy, while PBVi remained within normal range in treated patients with HFpEF or HFmrEF. Assessment by CMR may provide incremental clinical value as a marker of pulmonary congestion in suspected HF and for evaluating response to decongestive treatment.