Exuberant late gadolinium enhancement in hypertrophic cardiomyopathy as a precursor to ‘burn out’

A 37-year-old man with a family history of hypertrophic cardiomyopathy (HCM) presented to an outside emergency department with dyspnoea, palpitations, upper normal troponins (troponin I values of 0.26 ng/mL, 0.24 ng/mL, and 0.23 ng/mL with reference range <0.29 ng/mL), and an elevated BNP of 771 pg/mL (reference range <100 pg/mL). Transthoracic echocardiogram demonstrated features of HCM without left ventricular (LV) outflow tract obstruction (Supplementary material online, Video S1). Initial findings including mild LV systolic dysfunction [LV ejection fraction (LVEF) 45%] prompted coronary angiography, which excluded epicardial coronary artery disease (Supplementary material online, Videos S2 and S3). Initial electrocardiogram (ECG) demonstrated normal sinus rhythm with right axis superior deviation, right atrial enlargement, and right ventricle hypertrophy (Supplementary material online, Figure S1). While the ECG did not show LV hypertrophy as might be expected for HCM, retrospectively applied automated artificial intellgence ECG analysis predicted a probability of HCM of 96.43%. The utilized artificial intelligence ECG application is a deep learning convolutional neural network application with area under the curve of diagnosing HCM by ECG alone of 0.96 (95% CI 0.95–0.96) with a sensitivity of 87% and specificity of 90%.¹ Cardiac MRI confirmed LV systolic dysfunction (LVEF 46%) (Supplementary material online, Video S4) and revealed exuberant, dense, diffuse, patchy LV late gadolinium enhancement (LGE) (Panels A–C, white arrowheads) with greatest density of LGE located at the RV insertion point on the basal anterior septum (black arrowhead). LGE was 43% of myocardial mass as determined using an auto-threshold method (cmr42, Circle CVI, Calgary, AB, Canada), with confirmation of semiautomated segmentation by visual assessment. Right ventricular biopsy (Panel D), performed to exclude infiltrative disease given the extent of LGE and LV systolic dysfunction, demonstrated marked myocyte hypertrophy, myocardial disarray, and interstitial fibrosis (asterisk), consistent with HCM. After shared decision-making, an implantable cardioverter defibrillator was pursued. Subsequent genetic testing revealed a heterozygous mutation in the MYBPC3 gene.

In light of the patient’s profound myocardial scar burden, early care discussions included anticipation of ‘burn out’ and cardiac transplantation. Over the ensuing 4 years, exertional dyspnoea and fatigue progressed despite guideline-directed medical therapy for LV systolic dysfunction. Clinical course was complicated by symptomatic atrial fibrillation requiring three ablations and hospitalization for decompensated heart failure. Cardiopulmonary exercise capacity and LV systolic function continued to decline (3.2 metabolic equivalents, LVEF 18%), with associated LV dilatation (Supplementary material online, Video S5). The patient underwent cardiac transplantation 5 years after initial evaluation. Study of his explanted heart revealed marked interstitial and replacement-type fibrosis (Panels E and F, white arrowheads and asterisk). Although ‘burn out’ is uncommon in HCM, exuberant LGE may predict clinical course.

Supplementary material

Supplementary material is available at European Heart Journal – Case Reports online.