Comparison of thallium myocardial scintigraphy after exercise and transoesophageal atrial pacing in the diagnosis of coronary artery disease.

Forty-nine patients admitted for assessment of chest pain underwent coronary angiography, planar Thallium 201 myocardial scintigraphy after submaximal exercise (TE) and transoesophageal atrial pacing (TAP). Early hypofixation with redistribution after 4 h indicated ischaemia. The criterion for a myocardial infarction (MI) was a fixed perfusion defect. Coronary angiography was carried out in all patients. Sixteen patients (group 1) had no MI and over 50% narrowing of at least one main coronary vessel. Ischaemia was noted in 10 of the 16 patients during exercise, and in 14 of the 16 patients during atrial pacing. The sensitivity for the prediction of coronary stenosis was 62% for TE and 87% for TAP. Nineteen patients (group 2) had had a previous MI. Reversible ischaemia was noted in 10 of the 19 patients during exercise, and in 11 of the 19 patients during TAP. Four of 14 patients with normal coronary arteries (group 3) had a reversible ischaemia with TE, and three of these same patients developed a positive scan with TAP. The respective specificities were 71% and 78%. Comparison of segmental hypoperfusion after TE and TAP gave identical results in 72 of the 80 segments studied in group I (90%), and in 88 of the 95 segments studied in group 2 (92%). The localizing value of TAP was good in left anterior descending (12 out of 18) and right coronary disease (16 out of 19), but poor in left circumflex stenosis (3 out of 9) misclassified as right coronary disease in four patients.(ABSTRACT TRUNCATED AT 250 WORDS)