Following a
myocardial infarction the patient with a dilated heart is at greater risk for arrhythmias, congestive failure and
sudden death. Studies of
myocardial infarction in experimental animals have shown that, with
infarcts involving up to 20% of the left ventricle,
hypertrophy of surviving myocytes occurs and there are minimal hemodynamic changes.
Infarctions greater than 20% induce little additional
hypertrophy, and develop increased left ventricular filling pressures and cardiac dilatation. It has been suggested that inadequate
hypertrophy of residual myocardium may be a reason for the progressive left ventricular dilatation which occurs after large
myocardial infarcts. There are data in humans and animals suggesting that the mass of the left ventricle following a
myocardial infarction correlates with improvement in systolic function. Studies from our laboratories have previously shown that
2-tetradecylglycidic acid, an inhibitor of
carnitine palmitoyl
transferase I, inhibits mitochondrial long-chain
fatty acid oxidation and causes myocardial
hypertrophy when given to rats by mouth for 7-28 days. We carried out studies to see whether induction of additional myocardial
hypertrophy by means of feeding tetradecylglycidic
acid might prevent pathologic dilation following a large (50%)
infarct in rats. Treatment of control and infarcted rats with tetradecylglycidic
acid for 10 days resulted in myocardial
hypertrophy in both groups. The rats with
myocardial infarction treated with tetradecylglycidic
acid had an increase in peak developed left ventricular pressure during abrupt aortic occlusion and lower left ventricular end-diastolic volumes, when compared to untreated rats with
myocardial infarction, while the stroke volume was maintained. Thus induction of myocardial
hypertrophy with an inhibitor of long-chain
fatty acid oxidation retarded the process of left ventricular dilatation and had beneficial effects on systolic function following a large
myocardial infarction.