Clinical Outcomes and Prognosis
Muhammad Mustafa Alhussein, MD, MSc
Fellow
Uinversity of Calgary
Calgary, Alberta, Canada
Muhammad Mustafa Alhussein, MD, MSc
Fellow
Uinversity of Calgary
Calgary, Alberta, Canada
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
Brennan A. Ballantyne, MD
Fellow
Libin Cardiovascular Institute of Alberta
Calgary, Alberta, Canada
Bert Vandenberk, MD
Fellow
Libin Cardiovascular Institute of Alberta
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
Derek Exner, MD
Professor
Libin Cardiovascular Institute of Alberta
Calgary, Alberta, Canada
Stephen B. Wilton, MD, MSc
Associate Professor
Cumming School of Medicine, University of Calgary
Calgary, Alberta, Canada
James White, MD
Professor of Cardiology
Stephenson Cardiac Imaging Centre
Calgary, Alberta, Canada
Arrhythmia risk stratification in ischemic cardiomyopathy (ICM) remains dominantly guided by left ventricular ejection fraction (LVEF). Prior studies suggest an incremental role for late gadolinium enhancement (LGE) quantification to improve risk stratification. However, integration of scar quantification in routine practice has not been achieved due to its time-consuming nature, lack of technique consensus, and frequent need to consider image artifacts. We sought to assess the feasibility and prognostic value of pragmatic, visual sub-segmental scoring in routine practice assisted by a graphical reporting tool encouraging clinicians to visually match the appearance of LGE images. The value of this to predict life-threatening arrhythmic events was tested.
Methods:
1,093 patients with a CMR-based diagnosis of ICM were identified from the Cardiac Imaging Registry of Calgary (CIROC). Baseline health questionnaires and electronic health data were collected following electronic consent and patients were prospectively followed for the composite arrhythmic outcome of sudden cardiac death, survived sudden cardiac arrest, unstable ventricular tachycardia, or appropriate ICD therapy (adjudicated). Studies were clinically interpreted using standardized reporting software (cardioDITM, Cohesic Inc., Calgary) incorporating a 68-subsegmental graphical interface for rapid visual estimation of LGE (veLGE) burden (4 subsegments assigned for each of the 17 AHA segments)(Figure 1). veLGE was expressed as percentage of all 68 subsegments. Chamber volumetry was performed using cvi42 (Circle Cardiovascular Inc., Calgary) with data migration for reporting and data management. veLGE% was assessed by multivariable analysis for independent association with the composite arrhythmic outcome.
Results:
Mean age was 63.3 ± 10.7 years with 83% male. Baseline characteristics are shown in Table 1. Over a median 3.8 years the composite arrhythmic outcome was experienced by 89 (8.1%) patients. Patients experiencing this outcome showed higher prevalence of atrial fibrillation, wider QRS, lower bi-ventricular EF, and increased LVEDVi. veLGE% was significantly higher in patients experiencing the arrhythmic outcome (30% vs 23%, p=0.001). Following adjustment for baseline variables, veLGE% remained an independent predictor of the primary outcome (HR 1.02 per 1%, p=0.027). Using an optimal ROC-defined threshold of veLGE ≥ 35%, patients above this threshold experienced a 1.9-fold increased risk of arrhythmic events (HR of 1.87 [1.23-2.85], p=0.004). In patients with LVEF ≤35% the presence of veLGE ≥35% was associated with an incremental 2.8-fold risk of the primary outcome (aHR 2.78 [1.61-4.79], p< 0.001) (Figure 2).
Conclusion:
In a large population of patients with ICM, veLGE quantification was ubiquitously achieved in routine clinical practice and was associated with independent prognostic value for the prediction of future life-threatening ventricular arrhythmias.