Abstract 2160: Myocarditis in Hypertrophic Cardiomyopathy Patients Presenting Acute Clinical Deterioration
Introduction: The extreme variability in the phenotype and progression of hypertrophic cardiomyopathy (HCM) is still largely unexplained.
Hypothesis: Myocarditis can be a major cause of acute electrical instability or clinical deterioration in HCM patients.
Methods: One hundred-nineteen HCM patients (69M/50F, mean age 41±8 ys), 42 with acute clinical deterioration including electrical instability and/or rapidly worsening heart failure, and 77 clinically stable, underwent cardiac catheterization with left ventricular (LV) endomyocardial biopsy and gene analysis of major sarcomeric proteins. Biopsies were processed for histology, immunohistochemistry for inflammatory infiltrates characterization and polymerase chain reaction for the most common cardiotropic viruses. Controls were 50 normal surgical samples.
Results: All 119 patients showed histological findings suggestive of HCM. In addition CD45RO+ lymphocytes (≥14/mm2) with focal necrosis of the adjacent severely hypertrophied and often disorganized myocytes (Figure⇓) , consistent with an overlapping active myocarditis, were observed in 28 of 42 unstable and none of 77 stable HCM patients. A viral genome was detected in 14 of 28 patients with myocarditis (adenovirus in 5, enterovirus in 3, influenza virus in 3, Epstein-Barr virus in 2, HCV in 1) and in none of HCM patients without and in controls. No correlation between sarcomeric protein gene mutations and HCM clinical profile was observed
Conclusions: Myocarditis, often viral, represents a common cause of acute clinical deterioration in HCM. Its recognition can potentially affect disease prognosis and treatment