Impact of Beta Blockers on Dobutamine-Atropine Stress Echocardiography

Dobutamine increases oxygen demand in the myocardium and is used in conjunction with echocardiography to detect coronary artery disease. Beta blockers (BB) are partial antagonists of dobutamine and, therefore, offset dobutamine effects. Still, the impact of BB therapy on dobutamine stress echocardiography is not clear. One hundred forty-one dobutamine-atropine echocardiographic studies have retrospectively been analyzed: 27 patients were on BB (19%; group I); and 114 off BB (81%; group II). Coronary angiography was performed in a similar percentage of patients (97% and 85%, respectively; P = NS). No differences in clinical and angiographic profile were found between the groups. Sensitivity (83% vs 71%; P = NS) and specificity (100% vs 95%; P = NS) for coronary artery disease were similar in both groups. Atropine was infused more frequently to patients from group I (67% vs 46%; P = 0.04). Limiting side effects and prolonged ischemia presented with the same frequency in both groups. When the dobutamine test was positive, severe extent of ischemia appeared more often in patients from group I than in patients from group II (66% vs 33%; P = 0.03). The majority of patients from group I (55%) with severe extent of ischemia and only 12% from group II received atropine (P = 0.02). No differences were found in dobutamine time and extent of ischemia in patients from group I who had a positive response to dobutamine. On the contrary, patients from group II with one vessel disease had a dobutamine time longer (10.5 +/- 3.8 vs 7.8 +/- 3.7 min; P < 0.05) and extent of ischemia smaller (1.8 +/- 0.4 vs 2.6 +/- 0.5 segments; P < 0.05) than patients from group II with multivessel disease. We conclude that: 1) sensitivity of dobutamine-atropine echocardiography for diagnosis of coronary artery disease remains even if patients are on BB; 2) patients with significant coronary artery disease who are taking BB often develop severe myocardial ischemia during dobutamine-atropine stress echocardiography; and 3) BB therapy precludes stratification of a positive echocardiographic response. These conclusions should be confirmed in a prospective study to be considered as definitive. (ECHOCARDIOGRAPHY, Volume 13, July 1996)