Does Isovolumic Relaxation Time Reflect the Severity of Left Ventricular Hypertrophy in Patientswith Essential Hypertension?

To elucidate whether the isovolumic relaxation time (IRT) reflects the severity of left ventricular hypertrophy, IRT and left ventricular mass index (LVMI) were measured in 43 patients with essential hypertension and in 17 normotensive controls. The hypertensive patients were subdivided into three groups based on interventricular septal thickness (IVST) and left ventricular posterior wall thickness (PWT), determined echocardiographically, and clinical symptoms. IVST and PWT in group 1 patients (n = 10) were less than 10 mm, IVST and/or PWT in group 2 (n = 23) were 10 mm or greater, and the hypertensive patients in group 3 (n = 10) were in class III of the New York Heart Association Classification of hypertension. The IRT was prolonged in accordance with the increase in LVMI in groups 1 and 2. Though the LVMI showed no significant difference between normotensive controls and group 1, the IRT was significantly longer in group 1 patients (p < 0.05). The LVMI was markedly greater in group 3 than in group 2 (p < 0.01), but the IRT showed no significant difference. This finding indicates that there might be a limit of IRT prolongation associated with myocardial hypertrophy due to essential hypertension. In conclusion, IRT reflects the severity of left ventricular hypertrophy in patients with mild to moderate essential hypertension, but does not in advanced stages of hypertension.