Retrospective analysis of hemodynamic factors was performed on hypertensive participants of our Multiple Risk Factor Intervention Trial (MRFIT) center to determine whether these may have a role in the higher mortality in a subgroup of special intervention (SI) participants with minor baseline electrocardiographic abnormalities. Stroke volume was estimated by a formula [SV = K(LVETxPP)x(1 + LVET/DP) where the K factor was determined using a separate group of individuals undergoing cardiac catheterization. The Pearson correlation between the two methods (dye dilution and above formula) was 0.7744 with a 95% confidence interval of 0.57-0.89 for the true correlation. In 222 SI and 186 usual care (UC) participants with no differences in stroke volume index (SVI) and cardiac output index (CI) at baseline, SVI and CI were systematically lower during the entire period of treatment in SI receiving higher average doses of thiazide diuretics. There was a moderate increase of SVI and CI in SI participants toward baseline after hydrochlorothiazide was replaced by other antihypertensive medication in the fourth year of the trial. We conclude that the lower SVI and CI could have been a contributing factor in the higher mortality in the SI group with ECG abnormalities resulting in decreased coronary flow reserve under stress conditions in these participants with probably pre-existing asymptomatic coronary artery disease
