Myocardial blood flow and efficiency in concentric and eccentric left ventricular hypertrophy

It is not clearly understood why concentric left ventricular hypertrophy (increased left ventricular mass and relative wall thickness) is associated with higher cardiovascular risk than eccentric hypertrophy (increased left ventricular mass but normal relative wall thickness). Possible reasons include lower myocardial efficiency or perfusion reserve in concentric than in eccentric hypertrophy. We compared myocardial perfusion reserve and efficiency in normotensive controls and in hypertensive patients with concentric and with eccentric hypertrophy.

Study subjects comprised 16 patients with hypertension-induced left ventricular hypertrophy and 10 normotensive controls. We measured myocardial perfusion reserve and oxygen consumption by positron emission tomography. We calculated myocardial efficiency by dividing left ventricular minute work by myocardial oxygen consumption.

There was no significant difference in myocardial perfusion reserve between patients with concentric (n = 9) as compared to eccentric (n = 7) hypertrophy. However, myocardial perfusion reserve in both patient groups were lower than in controls. Although myocardial efficiency in patients with eccentric hypertrophy and in controls were not different, both values were higher than measurements in patients with concentric hypertrophy (18% +/- 6% v 16% +/- 3% v 13% +/- 4%, eccentric hypertrophy versus controls versus concentric hypertrophy, respectively, P =.04 for both eccentric versus concentric hypertrophy and for controls versus concentric hypertrophy).

Myocardial efficiency but not perfusion reserve is lower in hearts with concentric compared with eccentric left ventricular hypertrophy. This might be an explanation for the higher cardiovascular morbidity and mortality associated with concentric left ventricular hypertrophy.