CMR Myocarditis Outcome

Study Questions:

What is the prognostic value of tissue characterization by cardiac magnetic resonance (CMR) in risk stratification of patients presenting with suspected myocarditis?

Methods:

The investigators enrolled 670 patients with suspected myocarditis who underwent CMR, including late gadolinium enhancement (LGE) parameters between 2002 and 2015, and were followed. They performed multivariable model for major adverse cardiac events (MACE) and determined the continuous net reclassification improvement (NRI) by LGE markers.

Results:

At a median follow-up of 4.7 years (interquartile range, 2.3-7.3), 98 patients experienced a MACE. A total of 294 (44%) patients demonstrated LGE presence, which was associated with a more than doubling risk of MACE (hazard ratio [HR], 2.22; 95% confidence interval [CI], 1.47-3.35; p < 0.001). Annualized MACE rates were 4.8% and 2.1% corresponding to LGE presence and absence, respectively (p < 0.001). In the multivariable model, LGE presence maintained significant association with MACE (HR, 1.72; 95% CI, 1.08-2.76; p = 0.023). The computed continuous NRI was 0.39 (95% CI, 0.10-0.67) when LGE presence was added to the multivariable model for MACE. Regarding location and pattern, septal and mid-wall LGE demonstrated the strongest associations with MACE (HR, 2.55; 95% CI, 1.77-3.83 and HR, 2.39; 95% CI, 1.54-3.69, respectively; both p < 0.001). A patchy distribution portended to a near threefold increased hazard to MACE (HR, 2.93; 95% CI, 1.79-4.80; p < 0.001). LGE extent (per 10% increase) corresponded to a 79% increase in risk of MACE (HR, 1.79; 95% CI, 1.25-2.57; p = 0.002). A normal CMR study corresponded to low annual MACE and death rates of 0.8% and 0.3%, respectively.

Conclusions:

The authors concluded that CMR tissue characterization provides effective risk stratification in patients with suspected myocarditis.

Perspective:

This observational study reports that key CMR variables of tissue characterization provide strong prognostic values in risk stratifying patients in this heterogeneous clinical setting. Furthermore, patients with a normal CMR have a significantly favorable outcome compared to those with an abnormal CMR study. Additional studies are indicated to validate these findings and identify genetic markers that predict the course of patients with suspected myocarditis, with the goal of developing new therapeutic strategies to treat myocarditis.

Clinical Topics: Heart Failure and Cardiomyopathies, Noninvasive Imaging, Acute Heart Failure, Magnetic Resonance Imaging

Keywords: Cardiac Imaging Techniques, Gadolinium, Heart Failure, Magnetic Resonance Imaging, Myocarditis, Prognosis, Risk


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