Intraventricular conduction disturbances and paroxysmal atrioventricular block in a young patient with MELAS.

We present the case of a 36-year-old male patient with MELAS (mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes) who developed intraventricular conduction disturbances and syncopal episodes due to a paroxysmal atrioventricular block. This case suggests that in MELAS, as well as in other mithochondriopathies, intraventricular conduction disturbances and atrioventricular block can be features of the disease. In our case, progression toward atrioventricular block was rapid, suggesting that in MELAS patients presenting with worsening conduction system anomalies, pacemaker implantation has to be considered without delay, irrespective of age.