Cardiac scintigraphic findings of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes: A case report

Abstract

A 49-year-old woman was admitted to hospital because of heart failure. She was diagnosed as having mitochondrial cardiomyopathy and diabetes mellitus. Echocardiography revealed a hypertrophic and poorly contracting left ventricle. A diagnosis of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes was established by muscle biopsy. She underwent technetium-99m-sestamibi ((99m)Tc-MIBI) and beta-methyl-p-(123)I-iodophenyl-pentadecanoic acid ((123)I-BMIPP) scintigraphic examinations. (99m)Tc-MIBI single-photon emission computed tomography revealed reduced tracer uptake in the hypertrophic left ventricular inferior wall. In contrast, there was an increase in (123)I-BMIPP uptake in the in the region of reduced (99m)Tc-MIBI uptake ((99m)Tc-MIBI/(123)I-BMIPP mismatch). There was rapid washout of (99m)Tc-MIBI from the myocardium (washout rate increased by 30%). Decreased (99m)Tc-MIBI and increased (123)I-BMIPP uptake ((99m)Tc-MIBI/(123)I-BMIPP mismatch) were the characteristics of cardiac involvement in mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes.

Keywords: 123I-BMIPP mismatch; 99mTc-MIBI; 99mTc-MIBI washout; MELAS.

Figure 1

Echocardiogram in the short-axis view showing left ventricular hypertrophy and left ventricular dilation with decreased contraction. A small amount of pericardial effusion is also noted

Figure 2

Southern blot analysis of mitochondrial DNA in the mitochondrial transfer RNA (Leu[UUR]) gene showing, in the presence of A3243G point mutation, the 322 bp polymerase chain reaction product is cut into a 206 bp and a 116 bp fragment. NC Negative control; PC Positive control

Figure 3

^99mTc-sestamibi (^99mTc-MIBI) (upper panel) and beta-methyl-p-¹²³I-iodophenyl-pentadecanoic acid (¹²³I-BMIPP) (lower panel) single-photon emission computed tomography images showing decreased ^99mTc-MIBI uptake in the inferoseptal segments and increased ¹²³I-BMIPP uptake in the inferoseptal and septal segments (^99mTc-MIBI/¹²³I-BMIPP mismatch)