Pathology of Hypertrophic Cardiomyopathy Leading to Congestive Heart Failure
TJ Honebrink, AG Rose. University of Minnesota, Minneapolis, MN
Background: Hypertrophic cardiomyopathy (HCM) is a recognized cause of sudden death in some patients with HCM. Recent studies indicate a better long term prognosis. Its association with left ventricular dilation and congestive heart failure (CHF) in 3.5-15% of longer surviving subjects with HCM is less widely appreciated. The mechanism of production of CHF in HCM is unknown.
Design: We studied the explanted hearts of two patients with HCM who received cardiac transplants for CHF. The patients' medical records as well as the hearts and glass slides and reports were reviewed. Note was made of the duration of symptoms of CHF, left ventricular ejection fraction (LVEF), heart weight, presence of asymmetric septal hypertrophy (ASH) (ratio of VS to LVFW), presence of mirror image plaque in LV outflow tract, mean diameter of mid-portion of LV cavity (two measurements at right angles to each other: antero-posterior and lateral), presence and severity of LV replacement fibrosis (0 = no fibrosis; + = mild fibrosis, affecting < 10% of the myocardium, ++ = moderate, 10-20% and +++ = severe fibrosis, >20%); and the presence of small coronary artery disease (SCAD). The pathology was reviewed with reference to establishing a cause for the onset of CHF. Two randomly selected autopsy patients with HCM without CHF (aged 61 and 70 years) served as histological controls.
Results: Both hearts (Table) showed a severe degree of replacement fibrosis of the LV myocardium as well as SCAD. Patient 1 (24 mths symptoms of CHF) showed fibrosis of about 50% of the left ventricular myocardium and patient 2 (1 mth symptoms of CHF) showed 15% fibrosis. The fibrosis evolves via from ischemia induced myocyte vacuolation and myocytolysis. The controls both showed grade 1+ replacement fibrosis with heart weights of 820 gm and 460 gm, respectively. One out of two (1/2) controls showed SCAD; neither control showed ASH.
|Age (year), Sex||LVEF||Heart Weight (gm)||Asymmetric Septal Hypertrophy (ratio)||Mirror Image Plaque||LV Cavity Diameter (mean, cm)||LV Fibrosis||Small Coronary Disease|
|Patient 1, 20, F||15%||441||Yes (1.5)||No||2.1||+++||Yes|
|Patient 2, 28, F||35%||500||Yes (1.7)||No||2.5||++||Yes|
Conclusions: Replacement fibrosis of hypertrophied myocardium associated with dysplastic SCAD appears to be the basis for the onset of ventricular systolic dysfunction that is imperfectly compensated for by ventricular dilatation. The young age of both of the patients is noteworthy and indicates that heart failure may occur at a relatively early stage of the course of HCM and without severe LV dilatation.
Monday, March 9, 2009 9:30 AM
Poster Session I Stowell-Orbison/Autopsy Award # 5, Monday Morning