Myocardial Metabolic Abnormality in a Patient With Uremic Cardiomyopathy

A 73-year-old Japanese man with endstage renal disease was admitted to hospital because of heart failure. He had been started on hemodialysis 3 years prior because of immunoglobulin A nephropathy. His blood pressure was 112/72 mmHg, and pulse rate was 72 beats/min. He had had hypertension for 20 years and there was no family history of cardiomyopathy.

His laboratory data showed only mild anemia (hemoglobin, 10.2 g/dL), excepting the renal and heart failure. ECG revealed sinus rhythm with mild left ventricular hypertrophy. Chest X-ray showed cardiomegaly (cardiothoracic ratio 60%). Transthoracic echocardiography demonstrated diffuse hypokinesis of the dilated left ventricle (LV) (ejection fraction, 35%; end-diastolic diameter, 56 mm) without hypertrophy (LV wall thickness, 10 mm), although the ejection fraction was 60% before starting hemodialysis.

¹²³I-β-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) and ²⁰¹thallium dual myocardial single-photon emission computed tomography demonstrated perfusion-metabolism mismatch showing normal perfusion and lower BMIPP uptake in the anteroseptal and inferior walls of the LV (Figure A). Because coronary angiography showed normal coronary arteries, a right ventricular endomyocardial biopsy was obtained. Microscopically, perivascular fibrosis, and a difference in the size of myocytes with vacuolar degeneration were seen (Figure B,C) although capillary density was normal (Figure D).

Figure.

¹²³I-β-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) and ²⁰¹thallium (Tl) dual myocardial single-photon emission computed tomography demonstrate perfusion-metabolism mismatch showing normal perfusion and lower BMIPP uptake (A, Upper, BMIPP; Lower, Tl). Endomyocardial biopsy shows mild interstitial fibrosis (B; Azan, ×100), vacuolar degeneration in various sized myocytes (C; H&E, ×200), and normal capillary density (D; immunostaining for CD 31, ×200).

These findings suggested that the myocardial metabolic abnormality may be related to systolic dysfunction in the present patient with uremic (or hemodialysis-related) cardiomyopathy. Although its mechanisms are unknown, ischemia with non-obstructive coronary artery (INOCA) related to endothelial dysfunction and repeated reduction in myocardial blood flow by hemodialysis may induce a metabolic abnormality with regional differences that is unlikely to be seen in dilated cardiomyopathy.

Disclosures

K.M. is a member of Circulation Journal’s Editorial Team. The authors declare no conflicts of interest.