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A 27-year-old man was admitted to hospital because of severe cardiac failure. Investigation revealed dilated cardiomyopathy with a left ventricular ejection fraction of 15–20%. During adolescence the patient had been investigated for growth retardation and he also had progressive external ophthalmoplegia. There had been no symptoms of cardiac disease until 2 weeks before admittance. An endomyocardial biopsy showed cardiomyocytes deficient in cytochrome c oxidase (COX) in a mosaic pattern. A skeletal muscle biopsy showed mitochondrial myopathy with COX-deficient ragged-red fibers. Molecular genetic analysis revealed a heteroplasmic, 3.8-kb, mitochondrial DNA (mtDNA) deletion in heart and muscle. PCR-based quantification of the proportion of mtDNA with deletion showed 47% mutated mtDNA in the myocardial biopsy and 68% in muscle. In spite of treatment, the condition deteriorated and the patient died 5 days after admittance. This case demonstrates that mtDNA deletions may occasionally be the cause of severe dilated cardiomyopathy, and that morphological and molecular genetic diagnosis may be obtained by endomyocardial biopsy.

Earlier studies have shown that spinal cord stimulation (SCS) has antianginal and anti-ischemic effects in severe coronary artery disease. In the present study, 14 patients were subjected to right-sided atrial catheterization and atrial pacing. The patients were paced to angina during a control session and during spinal cord stimulation. Myocardial extraction of β-endorphin (BE) during control pacing (8 ± 22%) changed to release at the maximum pacing rate during treatment (–21 ± 47%, a negative value representing release). Furthermore, the results indicate local myocardial turnover of leuenkephalin, BE and calcitonin-gene-related peptide. In addition, it is implied that SCS may induce myocardial release of BE which could explain the beneficial effects in myocardial ischemia.