Non-ischemic or Dual Cardiomyopathy in Patients with Coronary Artery Disease

Abstract

Background: Randomized trials in obstructive coronary artery disease (CAD) have largely shown no prognostic benefit from coronary revascularization. While there are several potential reasons for the lack of benefit, an underexplored possible reason is the presence of coincidental non-ischemic cardiomyopathy (NICM). We investigated the prevalence and prognostic significance of NICM in patients with CAD (CAD-NICM). Methods: We conducted a registry study of consecutive patients with obstructive CAD on coronary angiography who underwent contrast-enhanced cardiovascular magnetic resonance imaging (CMR) for the assessment of ventricular function and scar at 4 hospitals from 2004 to 2020. We identified the presence and cause of cardiomyopathy using CMR and coronary angiography data, blinded to clinical outcomes. The primary outcome was a composite of all-cause death or heart failure (HF) hospitalization, and secondary outcomes were all-cause death, HF hospitalization, and cardiovascular death. Results: Among 3,023 patients (median age 66 years, 76% men), 18.2% had no cardiomyopathy (CAD+noCM), 64.8% had ischemic cardiomyopathy (CAD+ICM), 9.3% had CAD+NICM, and 7.7% had dual cardiomyopathy (CAD+dualCM) defined as both ICM and NICM. Thus, 16.9% had CAD+NICM or dualCM. During a median follow-up of 4.8 years (interquartile range, 2.9, 7.6), 1,116 patients experienced the primary outcome. In Cox multivariable analysis, CAD+NICM or dualCM was independently associated with a higher risk of the primary outcome compared with CAD+ICM [adjusted hazard ratio (HR) 1.23; 95% confidence interval (CI) 1.06-1.43; P = 0.007] after adjustment for potential confounders. The risks of the secondary outcomes of all-cause death and HF hospitalization were also higher with CAD+NICM or dualCM (HR 1.21; 95% CI 1.02-1.43; P = 0.032 and HR 1.37; 95% CI 1.11-1.69; P = 0.003 respectively), while the risk of cardiovascular death did not differ from that of CAD+ICM (HR 1.15; 95% CI 0.89-1.48; P = 0.28). Conclusions: In patients with CAD referred for clinical CMR, NICM or dualCM was identified in 1 of every 6 patients and was associated with worse long-term outcomes compared with ICM. In patients with obstructive CAD, coincidental NICM or dualCM may contribute to the lack of prognostic benefit from coronary revascularization.