OBJECTIVES This study investigated the prognostic value of left ventricular (LV) mass at echocardiography in uncomplicated subjects with essential hypertension. BACKGROUND Only a few single-center studies support the prognostic value of LV mass in uncomplicated hypertension. METHODS The MAssa Ventricolare sinistra nell'Ipertensione study was a multicenter (45 centers) prospective study. The prespecified aim was to explore the prognostic value of LV mass in hypertension. Admission criteria included essential hypertension, no previous cardiovascular events, and age Ն50. There was central reading of echocardiographic tracings. Treatment was tailored to the single subject. RESULTS Overall, 1,033 subjects (396 men) were followed for 0 to 4 years (median, 3 years). Mean age at entry was 60 years, and systolic/diastolic blood pressure was 154/92 mm Hg. The rate of cardiovascular events (ϫ100 patient-years) was 1.3 in the group with normal LV mass and 3.2 in the group (28.5% of total sample) with LV mass Ն125 g/body surface area (p ϭ 0.005). After adjustment for age (p Ͻ 0.01), diabetes (p Ͻ 0.01), cigarette smoking (p Ͻ 0.01) and serum creatinine (p ϭ 0.03), LV hypertrophy was associated with an increased risk of events (RR [relative risk] 2.08; 95% CI [confidence interval]: 1.22 to 3.57). For each 39 g/m 2 (1 SD) increase in LV mass there was an independent 40% rise in the risk of major cardiovascular events (95% CI: 14 to 72; p ϭ 0.0013). CONCLUSIONS Our findings show a strong, continuous and independent relationship of LV mass to subsequent cardiovascular morbidity. This is the first study to extend such demonstration to a large nationwide multicenter sample of uncomplicated subjects with essential hypertension. (J Am Coll Cardiol 2001;38:1829 –35) © 2001 by the American College of Cardiology It is generally established that left ventricular (LV) mass determined at echocardiography is a powerful predictor of cardiovascular disease in apparently uncomplicated subjects with essential hypertension (1,2). However, only two single-center studies explored the prognostic value of LV mass (3,4) in the specific setting of initially uncomplicated sub-jects with essential hypertension. Evidence that serial changes in LV mass over time predict prognosis is also limited (5–7). The other outcome-based studies on the prognostic value of LV mass have been conducted in subjects with suspected coronary artery disease (8), previous myocardial infarction (MI) (9), renal failure (10,11), or in the general population (12,13). Hence, although a large body of evidence indicates the prognostic value of LV mass in different clinical settings, the specific applicability of these results to the clinical management of the vast majority of uncomplicated subjects with essential hypertension re-mains poorly supported. To explore the prognostic value of LV mass at echocar-diography in the specific setting of uncomplicated subjects with essential hypertension, we planned the MAssa Ventri-colare sinistra nell'Ipertensione arteriosa (MAVI) study, a prospective, observational, multicenter investigation.