Coronary Artery Stenosis Treatment: Don't Rush to the Cath Lab

It is one of the trickiest clinical scenarios for cardiologists. A physician may encounter anatomically equivocal coronary stenoses during imaging, but assessing the need for interventional management of these lesions without a stress test remains challenging.

In these situations, taking a step back and utilizing stress testing to aid clinical decision-making—rather than rushing to the cath lab—is often a better approach to clinical management.

Coronary Artery Stenosis: Choosing a Functional or Anatomical Approach

In one case, a middle-aged mother of three came to me with mid-sternal chest tightness. Her days were filled from morning until night with working a full-time job, taking care of three children, and working through a crumbling marriage. It was no wonder she had a high level of stress and anxiety. Her symptoms came on whether she was angry, anxious, or agitated, and seemed to subside with deep breathing.

I thought back to the 2015 PROMISE trial from the New England Journal of Medicine, which randomly assigned patients to a functional (stress testing) vs. anatomical (Coronary CT angiogram) approach and found no difference in outcomes.¹ I concluded that, in this case, anatomical imaging would offer more information—not just about coronary stenosis but also about extracardiac structures such as the esophagus that might explain the patient's symptoms.

The CT coronary angiogram was preauthorized by my patient's insurance, but fractional flow reserve (FFR) was not included as part of the scan. When the results came back, I was left with even more of a clinical dilemma than when I had started: She had a 50% to 60% coronary artery stenosis in her mid-circumflex artery, a 20% to 30% coronary artery stenosis in her proximal to mid left anterior descending artery, and no significant stenosis in her right coronary artery. An echocardiogram I had previously ordered had already confirmed a normal left ventricular ejection fraction.

So, now what? Was that 50% to 60% anatomical lesion functionally significant? Was it causing her symptoms, or was it an incidental finding? Should I refer the patient for coronary angiogram or manage her medically?

I realized that this was not the time to go straight to the cath lab. Instead, I needed correlating functional information to go along with my anatomical imaging to make the best possible clinical decision for this patient. I referred her for an exercise stress test to see whether this lesion was associated with exercise-induced anginal symptoms and ECG changes.

Stress-Test Early and Stress-Test Often

Knowing that women can present with atypical symptoms of heart disease, the exercise stress test is perhaps one of the most valuable tools in the clinical cardiologist's toolbox. It is also useful for patients of any gender who have a sedentary life-styIe. Asking a patient to step on a treadmill can yield a wealth of information, including:

• The patient's exercise capacity adjusted for age
• Exercise-related hypoxemia
• Correlation of symptoms with exercise
• Exercise-related hemodynamics
• Prognostic information for cardiovascular mortality
• Electrocardiographic (and imaging, if added) changes associated with exercise

The diagnosis of a coronary lesion should always prompt aggressive medical management. But in many scenarios, a trip to the cath lab without evidence of functional hemodynamic significance may actually be more harmful than helpful.

According to the 2021 ACC/AHA Guidelines for Coronary Artery Revascularization, in patients with stable ischemic heart disease, normal left ventricular ejection fraction, and 1- or 2-vessel CAD not involving the proximal LAD, coronary revascularization is not recommended to improve survival.² Furthermore, in those who have ≥1 coronary arteries that are not anatomically or functionally significant (FFR>0.80), coronary revascularization should not be performed with the primary or sole intent of improving survival. The ACC/AHA guidelines go as far as to list this as a Class III Recommendation, which means it is potentially harmful, associated with excess morbidity/mortality, and should not be administered.³

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Skipping Stress Testing Can Cause Over-Treatment

Coronary CT angiograms are now recommended as an alternative to stress testing in both European and U.S. institutional cardiology guidelines, according to research published in the Journal of Cardiovascular Computed Tomography.⁴

Personally, I strongly support using coronary CT angiogram in select patients, like the middle-aged mother of three, because it offers a wealth of information about extracardiac structures as well as nonobstructive coronary artery disease. However, the interpretation and application of the coronary CT angiogram (which is an anatomical study in the absence of FFR) must be carefully taken within the context of the functional information offered by a stress test. Surveying all of this information first can help to prevent a rush to the cath lab and over-treatment as a result of excess, unnecessary revascularization.

A study published in JAMA Internal Medicine concluded that, compared with functional stress testing, CCTA was associated with an increased incidence of invasive angiography, revascularization, and coronary artery disease diagnosis.⁵ It also demonstrated no reduction in mortality or cardiac hospitalizations. There was an associated reduced incidence of myocardial infarction with CCTA, but some experts argue that this did not result from the increased revascularization.⁶ Instead, it was a reflection of greater use of medical therapy such as aspirin and statins in these patients after increased diagnosis of non-obstructive lesions.

Clinical Applications of Stress Testing

Cardiovascular clinicians can use stress testing in many ways to diagnose and guide treatment for patients with known or suspected CAD. First, it can be the initial diagnostic and prognostic test in a patient presenting with chest pain who has an intermediate probability of CAD. Second, it can supplement the CCTA, which provides anatomical information if an equivocal lesion is found. Finally, I find myself leaning heavily on stress tests for the many patients in whom "subclinical" atherosclerosis is detected via calcium score or as an incidental finding on a CT for another indication. This valuable diagnostic option remains a mainstay of coronary artery disease investigation in many clinical scenarios.

References:

1. Douglas PS, Hoffman U, Patel MR, et al. Outcomes of anatomical versus functional testing for coronary artery disease. The New England Journal of Medicine. Apr. 2015; 372: 1291-1300. https://www.nejm.org/doi/full/10.1056/nejmoa1415516
2. Lawton JS, Tamis-Holland JE, Bangalore S, et al. 2021 ACC/AHA/SCAI guideline for coronary artery revascularization: A report of the American College of Cardiology/American Heart Association joint committee on clinical practice guidelines. Journal of the American College of Cardiology. Jan 2022; 79(2): e21-e129. https://www.jacc.org/doi/10.1016/j.jacc.2021.09.006?_ga=2.91902621.669543370.1642953567-567500413.1640991586
3. Halperin JL, Levine GN, Al-Khatib SM, et al. Further evolution of the ACC/AHA clinical practice guideline recommendation classification system. Circulation. Sept. 2015; 133(14): 1426-1428. https://www.ahajournals.org/doi/full/10.1161/cir.0000000000000312
4. Al-Mallah MH, Aljizeeri A, Villines TC, et al. Cardiac computed tomography in current cardiology guidelines. Journal of Cardiovascular Computed Tomography. Sept. 2015; 9(6): 514-523. https://pubmed.ncbi.nlm.nih.gov/26456747/
5. Foy AJ, Dhruva SS, Peterson B, et al. Coronary computed tomography angiography vs functional stress testing for patients with suspected coronary artery disease. JAMA Internal Medicine. Nov. 2017; 177(11): 1623-1631. https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2655243?casa_token=LIzM49QZ5twAAAAA:1XMXwbcX27KYDsQzU8OPaFMEkgWveW6OueCKqslFfMQX26dpasYxeR2eSFbx34poeCM9jlrsmw
6. Foy AJ and Mandrola JM. Coronary computed tomographic angiography and potential for overtreatment—reply. JAMA Internal Medicine. Mar. 2018; 178(3): 436-437. https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2673427