Coronary Microvascular Dysfunction in Takotsubo Syndrome: Subtype-Specific Patterns Revealed by Invasive Assessment

Area of Science:

• Cardiology
• Vascular Biology
• Medical Imaging

Background:

• Coronary microvascular dysfunction (CMD) is a key mechanism in Takotsubo syndrome (TTS).
• The territorial distribution of CMD in different TTS phenotypes remains unclear.
• Investigating CMD in specific coronary artery territories is crucial for understanding TTS pathophysiology.

Purpose of the Study:

• To investigate the phenotype-specific territorial distribution of CMD in apical (AP) and midventricular (MV) Takotsubo syndrome.
• To differentiate CMD patterns within the left anterior descending artery (LAD) and left circumflex/obtuse marginal/ramus intermedius (LCx/OM/RI) territories.
• To explore the relationship between TTS phenotypes and specific microvascular dysfunction patterns.

Main Methods:

• Prospective single-center study of 31 acute TTS patients.
• Invasive assessment of coronary flow reserve (CFR), index of microcirculatory resistance (IMR), and fractional flow reserve (FFR) in LAD and LCx/OM/RI territories.
• CMD defined as CFR ≤ 2 and/or IMR > 25; subtypes Pattern A (CFR ≤ 2, IMR ≤ 25) and Pattern B (CFR ≤ 2, IMR > 25) distinguished.

Main Results:

• FFR excluded significant epicardial disease in all patients.
• 83.9% of patients exhibited abnormal microvascular parameters.
• Apical TTS showed significantly lower LAD-CFR and predominantly Pattern B in the LAD territory.
• Midventricular TTS demonstrated isolated LCx/OM/RI involvement.

Conclusions:

• Takotsubo syndrome exhibits a phenotype-specific territorial distribution of coronary microvascular dysfunction.
• Apical TTS is associated with Pattern B CMD in the LAD territory.
• Midventricular TTS is linked to isolated LCx/OM/RI microvascular dysfunction.
• Further research in larger cohorts is needed to confirm these phenotype-associated differences.