Electrocardiographic Left Ventricular Hypertrophy and Effects of Antihypertensive Drug Therapy in Hypertensive Participants in the Multiple Risk Factor Intervention Trial Stephen MacMahon, PhD, Gary Collins, BS, Pentti Rautaharju, MD, Jeffrey Cutler, MD, James Neaton, PhD, Ronald Prineas, MB, Richard Crow, MD, and Jeremiah Stamler, MD, for the Multiple Risk Factor Intervention Trial Research Group* Data are reported on electrocardiographic left ventricular hypertrophy (ECG LVH) among 8,012 men classified as hypertensive at baseline in the Multiple Risk Factor Intervention Trial. Compared with those allocated to the usual care (UC) control group, men allocated to the special intervention (SI) group experienced a mean reduction of 4 mm Hg in diastolic blood pressure and 7 mm Hg in systolic blood pressure, over 6 years of follow-up. There were 378 new cases of ECG LVH during follow-up; the incidence in the SI group was about 23% less than that in the UC group (4.2 vs 5.4% 2P x0.01). Among the 189 men with ECG LVH at baseline, those in the SI group experienced about 24% more annual follow-up visits at which they were free of ECG LVH (4.6 vs 3.7 visits; 2P <O.Ol). This re- duced incidence and increased reversal of ECG LVH in the SI group compared with that in the UC group was consistent with significant overall reduc- tions (2P <O.OOl) among SI men in mean wave am- plitude in those leads in which voltage is correlated with left ventricular mass (1 wave in Vs, R wave in aVL and S wave in Vs). In SI and UC groups com- bined, the presence of ECG LVH either at baseline or at follow-up was associated with several-fold in- creases in death from cardiovascular diseases in general, and death from coronary artery disease in particular. While mortality from cardiovascular dis- ease, including coronary artery disease, was not significantly different in SI and UC groups during follow-up, moderate though still potentially worth- while benefits that might accompany the observed ECG changes cannot be excluded. (Am J Cardiol 1989;63:202-210) lectrocardiographic left ventricular hypertrophy E (ECG LVH) appears to be an important prog- nostic indicator in patients with hypertension. In the Framingham Study, ECG LVH wasassociated with a 2-fold increase in mortality over that resulting from hypertension alone.’ For this reasonthere has beencon- siderable interest in the effectsof antihypertensivetreat- ment on LVH, whether determined by electrocardiogra- phy or echocardiography. In the Hypertension Detec- tion and Follow-Up Program2,3 after 5 years of follow-up, stepped-caretreatment for high blood pres- sure reduced the incidence of ECG LVH by approxi- mately one-third. In that study, among those with ECG LVH at entry, stepped-care treatment did not produce a significant increasein the reversal of ECG LVH during follow-up, but there appeared to be a reduction in R- wave voltage in those without ECG LVH at baseline, suggestinga possiblereduction in LV mass. Reductions in ECG voltage have also beenreported in a few smaller trials of antihypertensive therapy,4J although none has observed a significant increasein the reversalof discrete ECG criteria for LVH during follow-up. We report here data on ECG LVH in hypertensive participants of the Multiple Risk Factor Intervention Trial (MRFIT). The main aim of this randomized, pri- mary prevention trial was to determine the effects of a multifactorial intervention strategy, including stepped- care treatment for hypertension, on mortality from cor- onary artery disease in high risk, middle-agedmen, over 6 to 8 years of follow-up.6 A secondarygoal was to de- termine the effects of the intervention on morbidity from cardiovascular disease including ECG LVH.’ The From the Clinical Trials Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland, the Divisions of Biometry and Epidemi- ology, School of Public Health, University of Minnesota, Minneapolis, Minnesota, the Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada, and the Department of Community Health and Preventive Medicine, Northwestern University Medical School, Chicago, Illinois. Dr. MacMahon was the recipient of an Overseas Research Fellowship from the National Heart Foundation of Australia. Manuscript received May 31, 1988; revised manuscript received September 26, 1988, and accepted September 30. Address for reprints: Publications Coordinator, MRFIT Coordi- nating Center, Suite 508, 2829 University Avenue SE, Minneapolis MN 55414. *See Appendix. 202 THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 63