[1] Mexican Social Secur Inst, Med Res Unit Clin Epidemiol, Mexico City, DF, Mexico
[2] Metropolitan Hosp Quito, Quito, Ecuador
[3] Centroccidental Univ Lisandro Alvarado, Sch Med, Clin Pharmacol Unit, Barquisimeto, Venezuela
[4] Centroccidental Univ Lisandro Alvarado, Sch Med, Hypertens Clin, Barquisimeto, Venezuela
[5] Consorzio Mario Negri Sud, Chieti, Italy
[6] Italian Hosp Buenos Aires, Dept Cardiol, Buenos Aires, DF, Argentina
[7] Med Educ & Clin Res Ctr Norberto Quirno, Coronary Care Unit, Buenos Aires, DF, Argentina
[8] InterAmer Heart Fdn, Dallas, TX USA