Fifty-five patients with suspected coronary artery disease underwent planar thallium-201 myocardial scintigraphy after atrial transoesophageal pacing. Coronary angiography was carried out in all patients. Eighteen patients had no myocardial infarction, but a greater than 50% narrowing of at least one main vessel: initial hypoperfusion with redistribution at 4 h occurred in 16 patients (sensitivity 89%). Twenty-one patients had had a previous myocardial infarction: a reversible thallium defect was observed in 12 patients and an irreversible defect in the nine remaining patients. Sixteen patients had normal coronary arteries: a reversible thallium defect was observed in three patients (specificity 81%). After a mean follow-up of 22 +/- 13 months (range 6 to 40), 23 cardiac events occurred: cardiac death in one patient, unstable angina in three, and revascularization procedures for recurrent angina despite medical therapy in 19 (coronary artery bypass surgery in 7 and coronary angioplasty in 12). By univariate analysis, the predictors of future cardiac events were a history of previous myocardial infarction (odds ratio 5.5, P < 0.02), multivessel coronary artery disease (odds ratio 9.6, P < 0.0002), angina during atrial pacing (odds ratio 5.1, P < 0.05), abnormal scintigraphy (odds ratio 17.1, P < 0.001) and reversible perfusion defect after pacing (odds ratio 7.9, P < 0.002). By multivariate analysis, multivessel disease (P < 0.004) and reversible perfusion defect after pacing (P < 0.02) were the only independent predictors of future cardiac events.(ABSTRACT TRUNCATED AT 250 WORDS)