Progression of hypertrophic cardiomyopathy to dilated cardiomyopathy: a case reports and review of the literatures

Abstract

Left ventricular systolic function in hypertrophic cardiomyopathy (HCMP) does not usually deteriorate even in the end stage of the disease. However, occasionally cases of HCMP progress to a similar form of dilated cardiomyopathy (DCMP) with a decreased systolic function and dilated left ventricle. We report two cases of HCMP which progressed to DCMP during follow-up. Our cases have been documented by serial M-mode echocardiography which shows a prominent decrease in the left ventricular systolic function and a chamber enlargement of the left ventricle. There are various explanations of the pathogenesis of the functional and morphological myocardial deterioration of HCMP progressing to DCMP, and more cases should be studied to determine the pathogenesis and prevention of this end-stage feature of HCMP.

Findings of Cardiac Magnetic Resonance Imaging in Hypertrophic Cardiomyopathy after 16 Years

“…A small distinctive subset of HCMP patients (approximately 5–10%) show the evolution into the end stage (or "burned-out" phase), characterized by LV wall thinning, cavity enlargement and systolic dysfunction that resembles dilated CMP and produces a relentlessly progressive and irreversible heart failure. 1) 6) In 1998, Chang et al 7) demonstrated two cases of HCMP progressing to dilated CMP-like features after a follow-up period of more than 15 years with echocardiographic evidence, but there was no cardiac MRI evaluation. Chang et al 7) concluded that pathologic study of more cases is necessary to reveal the pathogenesis of the functional and morphological changes of the myocardium.…”

“… 1) 6) In 1998, Chang et al 7) demonstrated two cases of HCMP progressing to dilated CMP-like features after a follow-up period of more than 15 years with echocardiographic evidence, but there was no cardiac MRI evaluation. Chang et al 7) concluded that pathologic study of more cases is necessary to reveal the pathogenesis of the functional and morphological changes of the myocardium. In the previous study, end stage of HCMP among 44 cases was identified approximately after 14 ± 18 years.…”

Pathology of End-stage Remodeling in a Family of Cats with Hypertrophic Cardiomyopathy

“…12, 22, 27 Many mechanisms have been proposed for myocardial infarction in human HCM patients, including increased oxygen demand with decreased supply because of narrowing of the intramural coronary arteries related to atherosclerosis, coronary vessel spasm, intimal or medial hypertrophy of intramural coronary vessels, coronary vessel thromboembolism, or an increase in cardiac muscle mass beyond the ability of the coronary vessels to provide adequate blood flow. 3, 21 This last mechanism is far less likely as a primary cause because the echocardiographically measured IVS and LVFW dimensions are only moderately elevated and therefore would not be expected to impair the coronary vessels' ability to supply blood, although it might play a contributory role. Coronary vessel spasm has also been suggested as a cause of myocardial infarction in humans, but such a mechanism is difficult to demonstrate or disprove.…”

“…19 These abnormal coronary vessels typically have narrowed lumina and have been implicated as a cause of myocardial infarction. 3, 21, 22 These abnormal vessels are often more numerous in areas of fibrosis, suggesting a relationship between the two, although the nature of that relationship has not been identified. 12 Maron and Spirito 22 have proposed a mechanism for ES-HCM in human HCM patients in which the abnormal coronary vessels result in alterations of blood flow leading to myocardial ischemia, which causes myocardial cell death and subsequent replacement fibrosis.…”

“…12, 27 Coronary vessel spasm, increase of cardiac muscle mass beyond the ability of the vasculature to supply blood, and thromboembolism of the coronary arteries have also been suggested. 3 Ino et al 11 have recently suggested apoptosis as a primary cause of myocardial loss and subsequent fibrosis. Several recent papers suggest mutations in genes encoding various sarcomeric proteins and mitochondrial genes as underlying causes of ES-HCM.…”