Coronary Microvascular Dysfunction Alters the Pulsatile Behavior of the Resting Coronary Blood Flow

Area of Science:

• Cardiology
• Physiology
• Medical Imaging

Background:

• Resting pulsatile coronary flow velocity acceleration/deceleration (dU/dt) characteristics and their relationship with epicardial lesions and coronary microvascular dysfunction (CMD) are not fully understood.
• Understanding these variations is crucial for diagnosing and managing coronary artery disease.

Purpose of the Study:

• To investigate the association between resting coronary dU/dt patterns and different types of coronary microvascular dysfunction (CMD).
• To determine if epicardial disease severity influences resting dU/dt characteristics.
• To differentiate between functional and structural CMD based on dU/dt patterns.

Main Methods:

• Coronary dU/dt patterns were derived from the first derivative of intracoronary Doppler velocity signals.
• Univariable and multivariable models assessed relationships between dU/dt amplitudes, epicardial disease (FFR), and CMD.
• CMD was defined using coronary flow reserve (CFR) and microvascular resistance reserve (MRR).
• Functional CMD was characterized by blunted MRR and normal hyperemic microvascular resistance (hMR); structural CMD by blunted MRR and increased hMR.

Main Results:

• Functional CMD showed amplified 'a' and 'x' waves and blunted 'b', 'j', and 'z' waves.
• Structural CMD was associated with blunted 'a' waves and amplified 'j' waves.
• Epicardial disease severity had minimal association with resting dU/dt pattern alterations.

Conclusions:

• Coronary microvascular dysfunction (CMD) endotypes exhibit distinct resting intrabeat pulsatility characteristics.
• Resting dU/dt patterns are more indicative of CMD endotypes than epicardial disease severity.
• Elevated resting acceleration magnitudes do not necessarily imply a healthy microcirculation or the absence of CMD.