Refractory high output heart failure in a patient with primary mitochondrial respiratory chain disease

A 40-year-old man who was referred to our hospital due to dyspnea was found to have high output cardiac failure on Swan-Ganz catheterization. An endomyocardial biopsy revealed cardiomyocyte hypertrophy with a vacuolar structure consistent with mitochondrial disease (MD). The patient was discharged, then readmitted for high output cardiac failure with hypotension and hyperlactacidemia. Treatment with cardiopulmonary support and hemodiafiltration gradually improved his general condition, although it resulted in ischemic necrosis of the right leg. The hyperlactacidemia completely resolved after amputation, and the high output cardiac failure has not recurred for two years. High output cardiac failure is rare in MD patients and is related to myocardial abnormalities and hyperlactacidemia.