Increased thallium lung uptake after exercise in isolated left anterior descending coronary artery disease.

Increased thallium lung uptake during exercise correlates with an exercise-induced elevation in left ventricular filling pressure. This finding was analyzed in 48 patients with 1-vessel left anterior descending (LAD) coronary artery disease (CAD) before and after percutaneous transluminal coronary angioplasty. Patients were separated into 2 groups: 13 (27%) patients with increased (group 1) and 35 patients with normal thallium lung uptake (group 2). Compared with group 2, group 1 patients had more severe LAD luminal diameter narrowing (90 +/- 6% vs 81 +/- 11% [mean +/- standard deviation], p less than 0.003); slower clearance of thallium from the LAD territory segments (half-life 13.5 +/- 8.0 vs 6.5 +/- 5.0 hours, p less than 0.007); and more abnormal thallium segments per patient by quantitative criteria (p less than 0.02). After angioplasty, thallium lung uptake became normal in 12 of 13 patients in whom it was previously elevated. Increased thallium lung uptake after exercise occurs in 1-vessel LAD disease, and is related to the severity of ischemia by thallium scan and the severity of stenosis by angiography. Therefore, increased thallium lung uptake identifies a subset of patients with 1-vessel CAD with a greater amount of myocardium at risk.