Silent versus symptomatic ischemia during a thallium-201 exercise test.

Area of Science:

• Cardiology
• Nuclear Cardiology
• Exercise Physiology

Background:

• Thallium-201 (Tl-201) exercise testing is used to assess myocardial ischemia.
• Angina pectoris during exercise testing can indicate significant coronary artery disease.
• The presence or absence of angina in patients with Tl-201 redistribution requires further investigation regarding ischemia severity.

Purpose of the Study:

• To compare the extent and severity of myocardial ischemia in patients with exercise-induced Tl-201 redistribution, with and without concurrent angina.
• To identify predictors of early revascularization and adverse cardiac events in these patient groups.

Main Methods:

• Comparison of 134 patients with Tl-201 redistribution and no angina (Group 1) versus 134 patients with Tl-201 redistribution and angina (Group 2).
• Groups were matched for age, sex, and peak exercise heart rate.
• Analysis included ST-segment depression, Tl-201 imaging characteristics (redistributing defects, ischemic index), revascularization rates, and cardiac events.

Main Results:

• Patients without angina (Group 1) exhibited less frequent and less severe ischemic ST-segment depression compared to Group 2.
• Group 1 had less extensive and severe Tl-201 perfusion defects and a lower ischemic index.
• Fewer patients in Group 1 underwent early revascularization, with similar rates of adverse cardiac events between groups.

Conclusions:

• Exercise-induced Tl-201 redistribution without angina is associated with objectively less myocardial ischemia than when angina is present.
• The ischemic index and lung/heart Tl-201 uptake ratio were significant predictors in patients without angina.
• Maximal predicted heart rate and fixed left ventricular dilatation were significant predictors in patients with angina.