Determinants and prognostic significance of myocardial blood flow on cardiovascular magnetic resonance in dilated cardiomyopathy: a multicentre cohort study

Background Patients with dilated cardiomyopathy have altered myocardial perfusion, although the prognostic significance of perfusion abnormalities is unknown. In this study, we aimed to investigate whether myocardial perfusion reserve (MPR) assessed by stress perfusion cardiovascular magnetic resonance (CMR) in patients with dilated cardiomyopathy is independently associated with future adverse cardiovascular events. Methods In this multicentre cohort study, patients with dilated cardiomyopathy were recruited from three UK centres (Leeds General Infirmary, Glenfield Hospital, and Barts Heart Centre). The inclusion criteria comprised left ventricular dilatation, a left ventricular ejection fraction of less than 50%, and no clinical or CMR evidence of ischaemic heart disease. All participants underwent adenosine stress quantitative perfusion CMR between February 2018, and April 2024, to assess global stress and rest myocardial blood flow (MBF) and MPR. The primary outcome was a composite of first heart failure hospitalisation or death. Cox proportional hazards models were adjusted for age, sex, left ventricular ejection fraction, and non-ischaemic myocardial fibrosis. To identify the optimal cutoff values, a five-fold cross-validation approach was applied separately for each parameter. Findings Among the 549 patients enrolled, the mean age of the participants was 62 years (IQR 54–72); 349 (64%) were male participants and 200 (36%) were female. The primary endpoint occurred in 85 patients (15% of 549; 49 heart failure hospitalisations and 36 deaths) during a median follow-up of 3·1 years (IQR 1·8–4·8). Patients who met the primary outcome had lower MPR (p<0·001) and higher rest MBF (p<0·001) than those who did not, whereas stress MBF did not differ significantly between groups (p=0·06). Lower MPR (<2·44; hazard ratio 2·15 [95% CI 1·37–3·37], p<0·001), higher rest MBF (>0·64 mL/min per g; 2·20 [1·38–3·50], p<0·001), and lower stress MBF (<1·29 mL/min per g; 1·64 [1·02–2·61], p=0·04) were associated with the primary outcome after adjustment. Interpretation In patients with dilated cardiomyopathy, decreased MPR and increased rest MBF are associated with adverse prognosis, beyond established clinical and CMR risk markers. These perfusion parameters could offer prognostic value and warrant evaluation as therapeutic targets. The prognostic role of stress MBF in this cohort remains less certain.