Ischemia in aortic stenosis: Hemodynamic prediction

The records of 12 patients with aortic stenosis previously studied by Fallen et al. ¹ in 1967 before and after infusion of isoproterenol were reviewed to assess the value of hemodynamic indexes in predicting myocardial ischemia-defined as less than 5 percent transmyocardial lactate extraction or lactate production. Potential subendocardial blood supply was estimated from a diastolic pressure-time index (DPTI), calculated from aortic and left ventricular pressure, and oxygen demand, estimated from the tension-time index (TTI). The ratio DPTI TTI was used to estimate the supply/demand relation. Of eight patients with aortic stenosis but without associated coronary artery disease, four (Group A) metabolized lactate normally after administration of isoproterenol, and four (Group B) had biochemical evidence of ischemia. Three of four patients (Group C) with aortic stenosis and associated coronary artery disease had abnormal glycolysis after administration of isoproterenol. Calculated aortic valve areas were comparable in all groups. In patients with aortic stenosis alone, abnormal lactate metabolism occurred whenever DPTI/TTI was less than 0.30 (P < 0.01) (Group B). Two of three patients with aortic stenosis and associated coronary artery disease (Group C) showed abnormal lactate metabolism when DPTI/TTI was greater than 0.6; this ratio was below 0.3 in the third patient. These results suggest that the supply/demand relation calculated from these readily obtained indexes may be useful (1) in predicting in which patients with aortic stenosis ischemia will develop, (2) in distinguishing the role played by associated coronary artery disease, and (3) as an adjunct to calculation of valve area since the quantitation of associated aortic regurgitation is not necessary.