Patients with a normal exercise thallium-201 myocardial scintigram : always a good prognosis?

Abstract

The prognostic value of a normal exercise thallium-201 scintigram was determined in 211 patients with a normal exercise and resting scintigram. Endpoints were sudden cardiac death, non-fatal acute myocardial infarction and coronary artery bypass grafting or percutaneous transluminal coronary angioplasty. Forty patients (19%) had a history of a previous myocardial infarction and 40 (19%) were known to have had a previous percutaneous transluminal coronary angioplasty or coronary artery bypass grafting. Sixty-four patients (31%) were on treatment with β-blocking agents. After a mean follow-up period of 23.5 months, 22 patients had had a cardiac event (1 cardiac death, 6 myocardial infarction, 15 revascularization). For the total group, the 1-year event rate for cardiac death, myocardial infarction, percutaneous transluminal coronary angioplasty or coronary artery bypass grafting was 7.0%. For cardiac death or myocardial infarction alone the event rate was 2.8%. The only parameter independently predictive for cardiac events was the regular use of β-blocking agents. The high event rate in patients on β-blocking treatment is partly due to the fact that these patients were more symptomatic for coronary artery disease. The sustained β-adrenergic blockade in this patient group, even in patients advised to stop medication, was suspected to interfere with the results of ²⁰¹Tl scintigraphy. Therefore, more attention should be paid to patient instruction regarding the discontinuation of medication before the test.