Abstract 13262: Impaired Myocardial Perfusion Reserve is Associated With Adverse Cardiovascular Events in Patients With Dilated Cardiomyopathy

Introduction:Stress perfusion cardiovascular magnetic resonance (CMR) and PET data suggest the presence of microvascular dysfunction in non-ischaemic dilated cardiomyopathy (DCM) but its impact on clinical outcomes is unknown.Hypothesis:Impaired global stress myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) are associated with increased risk of adverse cardiovascular (CV) events.Methods:Adenosine stress perfusion CMR was undertaken on consecutive DCM patients.Stress and rest global MBF and MPR were derived using a modified Fermi-constrained deconvolution algorithm and follow-up data was collected. The primary outcome was a composite of CV death, CV hospitalization and major arrhythmic events. Cumulative incidence curves were constructed for the primary endpoint, stratified by the median value for stress MBF and a threshold of 1.5 for MPR, selected due to prognostic significance in other cardiac conditions. Cox proportional hazards modelling was performed, adjusting for age, sex, LVEF and midwall fibrosis.Results:Of 97 patients (63 men, median age 51 years, median LVEF 43%) followed up for median 1661 days, 17 met the primary endpoint. Stress MBF and MPR increased in line with a rise in LVEF (both p=0.01); there was no trend between rest MBF and LVEF (p=0.77). MBF below median and MPR<1.5 were significantly associated with increased cumulative incidence of the primary endpoint (log-rank p=0.02 and p=0.01, Fig 1). On multivariable modelling, a decreased rate of the primary outcome was associated with increased MPR (HR 0.44; 95%CI 0.2-0.96; p=0.04), with a non-significant increase in stress MBF (HR 0.69; 95%CI 0.46-1.06; p=0.09) and had no association with rest MBF (HR 1.08; 95%CI 0.47-2.46; p=0.86).Conclusion:Impaired MPR, driven by reduced stress MBF is associated with an increased risk of CV events, even after adjusting for LVEF. MPR may be a useful adjunct for DCM risk stratification and as a putative therapeutic target.