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Natural History of Patients With Ischemia and No Obstructive CAD
Quick Takes
- Women were more likely to have ischemia and no obstructive coronary artery disease (INOCA), but similar severity of ischemia compared to patients with obstructive coronary artery disease (CAD).
- In both INOCA and obstructive CAD, the ischemic burden on stress echocardiography and the severity of angina were not correlated, indicating the complex pathophysiology of angina.
Study Questions:
What is the natural history of symptoms and ischemia in patients with ischemia with no obstructive coronary artery disease (INOCA)?
Methods:
The international cohort study CIAO-ISCHEMIA (Changes in Ischemia and Angina over One year in ISCHEMIA trial screen failures with INOCA) trial enrolled participants from 2014-2019 with chronic stable angina and nonobstructive or normal coronary arteries on coronary computed tomography angiography. Angina assessments (Seattle Angina Questionnaire) and stress echocardiograms were performed. Medications were given according to clinician discretion. The primary outcome was the correlation between changes in angina score and change in echocardiographic ischemia. One-year predictors of changes in angina and ischemia were also analyzed. Participants were also compared to ISCHEMIA participants with obstructive coronary artery disease (CAD).
Results:
Participants in CIAO with INOCA were more often women (66% of 208) versus participants in the ISCHEMIA trial with obstructive CAD (26% of 865) (p < 0.001). The magnitude of ischemia was similar in both groups. At enrollment, there was no significant correlation between angina and ischemia. At 1 year, one-half of the participants with INOCA in CIAO had normal stress echocardiograms, and 23% had moderate or severe ischemia. At 1 year, angina had improved in 43% and worsened in 14%. There was no significant correlation between changes in ischemia and changes in angina at 1 year.
Conclusions:
The authors concluded that ischemia and angina often improved in participants with INOCA, but there was no significant correlation between the ischemic burden and severity of angina. There were similar wall motion abnormalities in participants with INOCA and obstructive CAD.
Perspective:
Women made up two-thirds of the INOCA cohort and only one-quarter of the cohort with obstructive CAD. In real-world clinical practice, INOCA is likely underdiagnosed. Recognition of INOCA is important because this study showed similar severity of ischemia and angina in patients with INOCA versus patients with obstructive CAD. Additionally, the severity of ischemia on stress echocardiography did not correlate with symptom severity, suggesting complex mechanisms of angina and the importance of symptom management to improve quality of life. The pathophysiology of INOCA is thought to involve microvascular dysfunction causing supply–demand mismatch. This study reported substantial reduction in both angina and ischemia over time. Reasons for symptomatic improvement are unclear, but may include lifestyle modifications, reassurance about the absence of obstructive CAD, episodic spasm, or medication changes. Further research is needed to elucidate the complex mechanisms and optimal management of INOCA.
Clinical Topics: Cardiovascular Care Team, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Stable Ischemic Heart Disease, Atherosclerotic Disease (CAD/PAD), Interventions and Coronary Artery Disease, Interventions and Imaging, Angiography, Computed Tomography, Echocardiography/Ultrasound, Nuclear Imaging, Chronic Angina
Keywords: Angina, Stable, Coronary Angiography, Coronary Artery Disease, Diagnostic Imaging, Echocardiography, Echocardiography, Stress, Ischemia, Life Style, Myocardial Ischemia, Quality of Life, Secondary Prevention, Spasm, Tomography, X-Ray Computed
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