Spontaneous Coronary Artery Dissection – Advanced Phenotyping and Risk Stratification in Key Subpopulations

Background

Spontaneous coronary artery dissection (SCAD) is an uncommon cause of myocardial infarction predominantly affecting women. It is caused by the development of a false lumen in the arterial wall leading to compression of the true lumen and myocardial infarction.

Methods

The thesis is comprised of three studies. Study one is a phenotyping study of women with a history of two or more SCAD events compared with matched healthy controls. Participants underwent clinical assessment and detailed phenotyping with brachial artery flow mediated dilatation, cardiopulmonary exercise testing, quantitative adenosine and psychological stress MRI perfusion and ambulatory ECG monitoring. Study two is a phenotyping study of men with SCAD compared with matched healthy controls, who underwent the same tests as the women. Study three is an observational study of a larger group of men from the SCAD registry; these men were compared to a previously studied female group in terms of demographic data, clinical history, risk factors and recurrent events.

Results

Cardiopulmonary exercise testing demonstrated both male and female SCAD patients to have a significantly greater increase in blood pressure per unit workload than healthy controls (P=0.002 for male, 0.02 for female). Female recurrent SCAD participants had lower myocardial perfusion reserve with psychological stress than healthy controls (P=0.022).

Men were found to have recurrent SCAD sooner than women, at 2.66 versus 4.43 years after their first SCAD.

Female SCAD patients showed greater flow mediated dilatation than healthy controls (P = 0.0145) whilst male SCAD patients had greater nitrate mediated dilatation (P=0.041).

Many of the other test results did not differ between SCAD patients and healthy controls.

Conclusions

SCAD survivors did not differ significantly from healthy controls in terms of measures of autonomic dysfunction or myocardial perfusion at rest and with adenosine stress.

Female SCAD patients had greater flow mediated dilatation than controls, whereas male SCAD patients had greater nitrate mediated dilatation.

Both female recurrent and male SCAD survivors showed an enhanced blood pressure response to exercise, and female recurrent patients showed a reduced level of perfusion with psychological stress.

Male SCAD patients experience recurrence earlier than female SCAD participants.