Clinical Outcomes and Prognosis
Ahmed Abdelhaleem, MD
Advanced Cardiac Imaging Fellow
West Virginia University Heart & Vascular Institute
Morgantown, West Virginia, United States
Ahmed Abdelhaleem, MD
Advanced Cardiac Imaging Fellow
West Virginia University Heart & Vascular Institute
Morgantown, West Virginia, United States
Dina Labib, MD, PhD, FSCMR
PhD student
Libin Cardiovascular Institute of Alberta, University of Calgary
Calgary, Alberta, Canada
Steven Dykstra, MSc, BSc
PhD Student
Libin Cardiovascular Institute of Alberta, University of Calgary
Calgary, Alberta, Canada
Robert J. Miller, MD
Associate professor of Cardiology
University of Calgary, Canada
Sandra Rivest, RN
Research nurse
Libin Cardiovascular Institute of Alberta, University of Calgary
Calgary, Alberta, Canada
Jacqueline Flewitt, MSc
Research Collaborations Coordinator
Libin Cardiovascular Institute of Alberta, University of Calgary
Calgary, Alberta, Canada
Andrew G. Howarth, MD, PhD
Clinical Co-director
Libin Cardiovascular Institute of Alberta, University of Calgary
Calgary, Alberta, Canada
Carmen P. Lydell, MD
Clinical Co-director
Libin Cardiovascular Institute of Alberta, University of Calgary
Calgary, Alberta, Canada
Nowell M. Fine, MD
Associate professor of cardiology
Libin Cardiovascular Institute
Calgary, Alberta, Canada
James White, MD
Professor of Cardiology
Stephenson Cardiac Imaging Centre
Calgary, Alberta, Canada
Objective criteria are published for the discrimination of hypokinetic non-dilated (HNDC) from dilated forms (DCM) of idiopathic non-ischemic cardiomyopathy (NICM), however, current practice rarely considers these when assigning disease labels or undertaking care decisions. The clinical relevance of adherence to such diagnostic criteria has not been systematically evaluated. In this observational cohort study, we comprehensively study differences between HNDC and DCM-classified patients with respect to their cardiac MRI-based phenotype, referral demographics, comorbidities, and clinical symptoms in addition to the association with major adverse cardiovascular events (MACE) over a median of a 3.6-year period of clinical follow-up.
Methods:
760 patients with idiopathic NICM and MRI-derived LVEF < 50% were identified from the Cardiovascular Imaging Registry of Calgary (CIROC). Patients with obstructive coronary artery disease, prior myocardial infarction, congenital heart disease, or any known cardiomyopathy diagnosis were excluded. Study subjects were stratified to HNDC or DCM based on sex-specific upper limits of normal ( >2SD) for indexed LV end-diastolic volume (LVEDVi). All patients underwent baseline health questionnaires, collection of laboratory, pharmacy, and 12-lead ECG data, and were prospectively followed for the composite MACE outcome of all-cause mortality, survived cardiac arrest, ventricular tachycardia or fibrillation, hospital admission for heart failure, cardiac transplant, or LVAD implantation.
Results:
Of 760 NICM patients, 517 (68%) met criteria for DCM and 243 (32%) for HNDC. Respective baseline demographics, health profiles and cardiac MRI phenotypes are provided in Table 1. Compared to DCM, HNDC patients were older and had a greater prevalence of hypertension, dyslipidemia, and atrial fibrillation with significantly higher LVEF (44.2 vs 30.9%, p< 0.001), lower LVmassi (59.6 vs 78.2 g/m2, p< 0.001), lower prevalence of mid-wall striae fibrosis (11 vs 40%, p< 0.001) and shorter QRS durations (100 vs 104 msec, p< 0.001).
Over a median follow-up of 3.6 years the primary outcome occurred in 26 (10.2%) HNDC versus 98 (19.0%) DCM patients (HR 0.56 [0.37-0.86]; p< 0.001). Kaplan-Meier curves for each cohort are provided in Figure 1. Multivariable modeling in the DCM cohort showed LVEF (aHR 0.969 per 1%, p=0.001) and mid-wall striae (aHR 1.7, p=0.01) to be independent predictors of the primary outcome. In the HNDC cohort, LVEF (aHR 0.938 per 1%, p=0.001) and female sex (aHR 1.15, p=0.02) were independent predictors, while mid-wall striae lost significance (aHR 1.7, p=0.39) following adjustment for age.
Conclusion:
Discrimination of HNDC from DCM by sex-specific LVEDVi thresholds establishes unique phenomic clusters with distinct distributions across all MRI-based markers, many demographic characteristics, and distinct incident rates of cardiovascular outcomes. These findings are of strong importance to future therapeutic guidelines and clinical decision-making.