Patients with coronary slow flow phenomenon demonstrate normal myocardial blood flow and arterial wave reflection...

Area of Science:

• Cardiology
• Vascular Physiology
• Diagnostic Imaging

Background:

• Coronary slow flow (CSF) is a syndrome of angina without significant coronary artery stenosis.
• The role of myocardial blood flow (MBF) and arterial characteristics in CSF symptoms is not well understood.
• This study investigated MBF, arterial stiffness, and wave reflection in CSF patients.

Purpose of the Study:

• To measure and compare myocardial blood flow (MBF) and MBF reserve in patients with coronary slow flow (CSF) versus controls.
• To assess and compare central arterial pressure waveforms, arterial stiffness, and wave reflection in CSF patients and controls.
• To determine if abnormalities in MBF or arterial properties contribute to CSF symptoms.

Main Methods:

• Ten CSF patients and 20 controls underwent dipyridamole-exercise stress myocardial contrast echocardiography.
• Myocardial blood flow (MBF), myocardial blood volume (A), and red cell velocity (beta) were quantified at rest and post-stress.
• Arterial waveform analysis, including augmentation index, aortic, and brachial pulse wave velocities, was performed.

Main Results:

• No significant differences were observed in resting or stress MBF, MBF reserve, or hemodynamic parameters between CSF patients and controls.
• Arterial stiffness, measured by aortic and brachial pulse wave velocities, was similar in both groups.
• Arterial wave reflection, assessed by augmentation index, did not differ significantly between CSF patients and controls.

Conclusions:

• Myocardial blood flow (MBF) and MBF reserve are normal in coronary slow flow (CSF) patients between acute episodes.
• Large artery stiffness and arterial wave reflection characteristics are also normal in CSF patients during quiescent periods.
• These findings suggest that CSF symptoms are not attributable to intrinsic abnormalities in these cardiovascular parameters.