Background Risk stratification in heart failure is important as it enables personalised care. A diagnosis of ischaemic cardiomyopathy (ICM) is important as it has a higher risk than non-ischaemic cardiomyopathy (NICM) and it may be treated with an ICD. Results of the Danish Study to Assess the Efficacy of ICDs in Patients with Non-ischemic Systolic Heart Failure on Mortality (DANISH) trial have suggested the prognostic benefit from defibrillator therapy in patients with NICM may be less than previously thought. Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) in a subendocardial or transmural pattern is validated for the detection of prior myocardial infarction. We hypothesised that the use of LGE CMR would alter the diagnosis of ICM in patients with newly presenting heart failure.
Methods We identified patients in the Leeds Heart Failure registry who had a clinically indicated CMR scan including LGE imaging. We also collected data on coronary angiogram findings, presence of previous myocardial infarction (MI), and revascularisation status (percutaneous coronary intervention and/or coronary bypass grafting). We classified patients with ICM by current American College of Cardiology (ACC) definition as used in trials such as the Surgical Treatment of Ischaemic Heart Failure Trial (STICH) by any of:
Prior revascularisation and significant coronary artery disease
75% stenosis of the Left Main Stem or left anterior descending coronary artery
75 % stenosis of both the Right coronary artery and the left circumflex artery
ICM was defined by CMR findings when a subendocardial or transmural pattern of LGE was identified by an independent level 3 CMR reporter. Concordance between ACC and CMR diagnosis of ICM was tested using Cohen’s Kappa statistic, with 1 implying complete agreement, and -1 complete disagreement. Net reclassification index was calculated to define how CMR modifies ACC definition of ICM.
Results 147 patients were included in the analysis. Their mean age was 61.3 (SEM 1.1), 79.5% were male, 19.9% had NYHA class 3 or 4 symptoms, and LV ejection fraction was 30 % (SEM 1%). Heart failure therapy included 54 % (SEM 3) of the maximum licenced dose of ACE inhibitor or ARB, 46% (SEM 3) of the maximum licenced dose of beta-blocker, and 43mg (SEM 4) furosemide per day. Overall, there was discordance between ACC and CMR definitions in 30 (20.4%) cases. The net reclassification index was 38.3%, with 7/62 cases of ICM diagnosed by CMR being classified by ACC definition as NICM, and 23/85 cases diagnosed as NICM by CMR being defined as per the ACC definition as ICM as demonstrated in case 1. There was significant disagreement between the two methods, with a Cohen’s Kappa statistic of 0.596 (SEM 0.064; p<0.001). Figure (Case1)
Conclusion Classification of ICM is significantly altered by using CMR with patients being reclassified in both directions. Further studies are needed to establish if this improves long term risk stratification in patients with ICM.
Conflict of Interest None
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