Mechanism and significance of a decrease in ejection fraction during exercise in patients with coronary artery...

Area of Science:

• Cardiology
• Diagnostic Imaging
• Exercise Physiology

Background:

• Patients with coronary artery disease (CAD) and resting left ventricular dysfunction (LVD) exhibit reduced ejection fraction (EF).
• Distinguishing exercise-induced EF decrease due to ischemia versus nonspecific ventricular response is clinically important.

Purpose of the Study:

• To determine if exercise-induced decrease in ejection fraction (EF) in patients with coronary artery disease (CAD) and left ventricular dysfunction (LVD) indicates ischemia or a nonspecific response.
• To correlate EF response with angiographic extent of CAD, angina severity, and long-term prognosis.

Main Methods:

• Radionuclide ejection fraction (EF) responses during exercise were compared between 246 patients with CAD/LVD and 48 patients with idiopathic dilated cardiomyopathy (IDCM).
• EF response was analyzed in relation to CAD extent, angina, chest pain, ST depression, and long-term mortality.
• Subgroup analysis was performed for moderate (EF 0.30-0.49) and severe (EF <0.30) LVD.

Main Results:

• A decrease in EF (≥0.01 or ≥0.05) occurred significantly more often in CAD patients (48%, 28%) than in IDCM patients (8%, 2%).
• Submaximal exercise-limited EF decrease occurred in 25% of CAD patients but none of the IDCM patients.
• CAD patients with exercise-induced EF decrease showed higher rates of three-vessel disease, chest pain/ST depression, and mortality.

Conclusions:

• In CAD patients with resting LVD, an exercise-induced EF decrease is a strong indicator of ischemia.
• A decrease of ≥0.05 EF or decrease during submaximal exercise is highly specific for ischemia.
• Exercise-induced EF decrease identifies a high-risk subgroup with multivessel CAD and poor long-term prognosis.