937-7 Is Lack of Hyperkinesis a “Normal Variant” During Dobutamine Stress? A Quantitative Two-Dimensional Echocardiographic Study

Abstract

Inotropic stimulation with simultaneous changes in heart rate and loading conditions can induce even in normal hearts a heterogeneity in wall motion and thickening, possibly mimicking an “ischemic” regional hypokinesia or lack of hyperkinesia during stress echocardiography. To describe in a quantitative fashion the physiologic contractile response of different left ventricular regions following dobutamine (dob) infusion, 223 in-hospital patients who underwent dobutamine stress echocardiography and coronary angiography were initially considered. Of these 223 patients, 18 had angiographically normal coronary arteries, normal resting function, negative ergonovine and exercise stress test, and negative Dob-stress echo; of the 18, only in 11 patients (6 females, age = 56 ± 10 years) it was possible to obtain quantitative measurements of the middle segments of the inferior, anterior, lateral, and septal wall (apical 4- and 2-chamber view). 2D-Echo measurements of wall thickness were obtained at end-diastolic (onset of q wave) and end-systolic phases, both at baseline (rest) and at peak dob (40 μg/min/kg plus atropine). During stress, % systolic thickening (%STh) decreased in the inferior wall (rest = 73 ± 24 vs dob = 50 (9%; P < 0.01), whereas it increased to a variable extent in the other regions, i. e. septal (rest = 46 ± 17 vs dob = 68 ± 13%, P < 0.01), anterior (rest 62 ± 19 vs dob = 69 (11%, p = ns), and lateral wall (rest = 48 ± 16 vs dob = 61 ± 18%, P = ns). The decrease in %STh of the inferior wall was inversely correlated with the increase in enddiastolic wall thickness (r = -0.75; p < 0.01), but neither with heart rate (r = 0.15; P = ns) nor with systolic blood pressure changes (r = 0.05; p = ns). In conclusion, heterogeneity of left ventricular wall thickening can be induced or magnified by dobutamine infusion even in subjects without coronary artery disease, with the inferior wall showing a lack of hyperkinesia, or even a relative hypokinesia, in comparison with other myocardial regions. Caution in aggressive dobutamine stress echocardiography reading, especially in the inferior wall, might be warranted.