Use imaging, interventional testing to help discern ischemia with nonobstructive CAD
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Key takeaways:
- Ischemia with nonobstructive coronary artery disease is common but underrecognized in women and portends worse prognosis.
- Use of multimodality imaging can help discern a diagnosis.
Women presenting with chest pain but without signs of obstructive coronary disease may still have microvascular dysfunction, and careful imaging analyses or invasive testing can help reveal the correct diagnosis, according to a speaker.
In a 2012 survey from the American Heart Association, most physicians, including 42% of cardiologists, reported suboptimal training on assessing CVD risks in women, Niti R. Aggarwal, MD, FACC, FASNC, assistant professor of medicine at the Mayo Clinic in Rochester and director of cardiac MRI at Mayo Clinic Health System, said during a presentation at the American Society of Nuclear Cardiology Scientific Session. Yet, imaging studies consistently demonstrate sex-based differences in disease presentation.
Image: Adobe Stock
Data show men have larger coronary arteries with low shear stress, resulting in disordered flow and a downregulated nitric oxide pathway with more inflammation and thrombosis, typically resulting in focal CAD. In contrast, women have smaller arteries with high shear stress with more laminar flow. This leads to upregulation of the nitric oxide pathways, less inflammation and thrombosis and more diffuse CAD, Aggarwal said.
Poor outcomes with INOCA
Women with ischemia with no obstructive CAD (INOCA) are at elevated risk for poor CV outcomes, and clinicians need to pinpoint the cause, Aggarwal said.
“Epicardial stenosis is far more common in men,” Aggarwal said. “Women, however, demonstrate the full spectrum of CAD, and that may include coronary microvascular dysfunction, vasospasm, myocardial bridging, inflammation and metabolic abnormalities. The CONFRIM registry also demonstrates that the presence of nonobstructive CAD is not benign and actually portends a worse prognosis.”
Patients with INOCA have a threefold increased risk for major adverse CV events with more events and CV death, more evidence of chest discomfort and worse quality of life, Aggarwal said.
“Yet, despite all of this, they are often reassured,” Aggarwal said.
For women or men reporting chest pain, clinicians should assess their risk factor profile and determine whether risk is low, intermediate or high. Based on that determination, initiate functional testing with imaging or angiography, proceeding down the pathway with stress echocardiography, PET imaging, cardiac MRI or anatomic CT, Aggarwal said.
Patients with coronary microvascular dysfunction not only have perfusion defects but can also have late gadolinium enhancement suggestive of scarring, Aggarwal said. T1 mapping in MRI, a more subclinical measure of fibrosis, can help reveal this, Aggarwal said. Additionally, stress profusion echocardiography can also be used to diagnose microvascular disease.
“The presence of microvascular disease on echo portends a worse prognosis than a normal stress echo and normal angiogram,” Aggarwal said.
Stress PET and cardiac MRI both have a class 2a indication for diagnosis, as does invasive angiography; stress echocardiography has a class 2b indication, Aggarwal said.
“If there is no obstructive CAD, I often go on to look for microvascular disease,” Aggarwal said.
Alternative pathways for diagnosis
Aggarwal also recommended alternate pathways to assess for disease. If a patient does not show obstructive disease on angiogram, perform a functional angiogram to assess further.
“Remember there are a lot of traditional CV risk factors that account for this, but there are other inflammatory and nontraditional CV risk factors,” Aggarwal said, adding that diagnosis can be made by imaging or invasive testing.
Aggarwal gave the example of a middle-aged patient with obesity who presents with exertional chest pain and has traditional risk factors including hypertension, hyperlipidemia and a premature family history of CAD. Yet, angiography demonstrates 30% luminal disease.
That patient should not be reassured that they do not have CAD, Aggarwal said.
“We should say to that patient, ‘The pain could still be coming from your heart and could be something called INOCA,” Aggarwal said. “Let’s do more imaging and interventional testing to determine what medications you need.”
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Aggarwal N. Coronary microvascular dysfunction. Presented at: ASNC2023 Scientific Session; Sept. 29-Oct. 1, 2023; Toronto (hybrid meeting).
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