ObjectiveTo determine whether type A behavior, which is associated with a risk of coronary heart disease, affects left ventricular hypertrophy in patients with essential hypertension.DesignCross-sectional study of 88 untreated patients with mild to moderate essential hypertension (33 men, mean ± SEM age 54 ± 1 years).MethodsWe measured the type A behavior score using a standardized questionnaire, left ventricular mass index using M-mode echocardiography and 24 h mean ambulatory blood pressure (recorded every 30 min). Beat-to-beat blood pressure was also measured using a Finapres device in patients at rest and during mental stress (counting backward) to determine the blood pressure response to stress.ResultsThe left ventricular mass index was correlated with the type A behavior score (r= 0.214,P< 0.05), age (r= 0.266,P< 0.05), 24 h mean systolic and diastolic blood pressures (r= 0.391,P< 0.001, andr= 0.382,P< 0.001, respectively), systolic blood pressure both at rest and during stress (r= 0.255,P< 0.05, andr= 0.215,P< 0.05, respectively), and the variability of both systolic and diastolic blood pressures at rest (r= 0.253,P< 0.05, andr= 0.321,P< 0.01, respectively). Stepwise multiple linear regression analysis demonstrated that age was associated with an increase in the left ventricular mass index for both sexes (P= 0.004 for males,P= 0.003 for females). The type A behavior score predicted a greater increase in left ventricular mass index in men (P= 0.018) but not in women. The 24 h mean systolic blood pressure was associated with a greater increase in left ventricular mass index in women (P< 0.001) but not in men.ConclusionType A behavior is an independent risk factor for left ventricular hypertrophy in male patients with essential hypertension.