Paradoxical ST-segment depression at high blood flow in ANOCA: a hypothesis-generating analysis

Area of Science:

• Cardiology
• Diagnostic Imaging
• Nuclear Medicine

Background:

• Angina with non-obstructive coronary arteries (ANOCA) is a frequent cause of chest pain.
• Microvascular dysfunction is increasingly recognized in ANOCA patients.

Purpose of the Study:

• To characterize ST-segment depression during dipyridamole rubidium-82 PET/CT MPI in ANOCA patients.
• To investigate the relationship between stress myocardial blood flow (MBF) and ST-segment depression in ANOCA.

Main Methods:

• Retrospective analysis of ANOCA patients and controls undergoing rubidium-82 PET/CT MPI.
• Categorization of stress MBF into low, normal, and high.
• Definition of ST-segment depression as ≥1 mm horizontal or downsloping depression.

Main Results:

• ST-segment depression occurred in 8.8% of ANOCA patients versus 4.7% of controls, predominantly in females.
• Prevalence of ST-segment depression was significantly higher with high stress MBF in both groups.
• ANOCA patients had a higher probability of ST-segment depression at any given stress MBF.

Conclusions:

• Vasodilator-induced ST-segment depression is more frequent at higher stress MBF, especially in ANOCA.
• This may represent a paradoxical "high-flow ischemia" phenotype.
• Further research is needed to elucidate mechanisms and prognostic implications.