Angiographic Coronary Slow Flow Is Not a Valid Surrogate for Invasively Diagnosed Coronary Microvascular Dysfunction.

Area of Science:

• Cardiology
• Vascular Biology
• Diagnostic Imaging

Background:

• Coronary microvascular dysfunction (CMD) is a common cause of ischemia with no obstructive coronary arteries.
• Current diagnostic criteria for CMD include assessing slow coronary flow using corrected TIMI frame count (cTFC).
• The relationship between angiographic slow flow (cTFC) and invasive coronary function testing (CFT) for CMD diagnosis remains unclear.

Purpose of the Study:

• To evaluate the correlation between cTFC and invasive CFT parameters in diagnosing CMD.
• To determine if angiographic slow flow is a reliable indicator of microvascular dysfunction.

Main Methods:

• Adult patients with ischemia and no obstructive coronary arteries underwent invasive CFT.
• Measurements included baseline coronary blood flow, coronary flow reserve (CFR), and index of microcirculatory resistance (IMR).
• Coronary slow flow was defined as cTFC >25 and CMD was defined by abnormal CFR and/or IMR.

Main Results:

• Of 508 adults, 49% had coronary slow flow.
• Slow flow was associated with higher odds of abnormal IMR but lower odds of abnormal CFR.
• cTFC showed weak correlations with baseline coronary blood flow, CFR, and IMR.

Conclusions:

• Coronary slow flow demonstrates a weak association with invasive CFT results.
• Angiographic slow flow should not be utilized as a substitute for invasive diagnostic methods for CMD.