From the Guidelines
Treatment for coronary microvascular dysfunction should prioritize a tailored approach based on the results of coronary flow reserve (CFR), index of microcirculatory resistance (IMR), and acetylcholine testing, with beta-blockers, ACE inhibitors, and statins being indicated for patients with abnormal CFR <2.0 or IMR ≥25 units and a negative acetylcholine provocation test. This approach is supported by the 2019 ESC guidelines for the diagnosis and management of chronic coronary syndromes 1. The guidelines suggest that patients with microvascular angina should be treated based on the dominant mechanism of microcirculatory dysfunction.
Key treatment considerations include:
- Beta-blockers to reduce heart rate and blood pressure
- ACE inhibitors to improve endothelial function
- Statins to reduce inflammation and improve microvascular function
- Lifestyle modifications, such as regular exercise, a heart-healthy diet, smoking cessation, stress management, and weight optimization
In contrast to older studies, such as the 2018 expert consensus document on personalized treatment of angina 1, which suggested a more empirical approach to treatment, the 2019 ESC guidelines provide a more tailored approach based on specific diagnostic tests. The CorMiCa trial, which randomized patients to a stratified medical treatment based on the results of CFR, IMR, and acetylcholine testing, supports this approach 1.
Overall, a personalized treatment plan based on the underlying pathophysiology of coronary microvascular dysfunction is essential to improve symptoms and quality of life for patients with this condition.
From the Research
Treatment Options for Coronary Microvascular Dysfunction
- Pharmacotherapy for coronary microvascular dysfunction (CMD) has shown promise in improving symptoms and quality of life, with potent statins in combination with angiotensin-converting enzyme inhibitor (ACE-I) or receptor blockers appearing to improve angina, stress testing, myocardial perfusion, coronary endothelial function, and microvascular function 2.
- The Coronary Microvascular Angina trial supports invasive diagnostic testing with stratified therapy as an approach to improve symptoms and quality of life 2.
- Intense medical therapy, including high-intensity statin, maximally tolerated ACE-I, and aspirin, is being tested in the WARRIOR trial to provide evidence for guidelines 2.
- Ranolazine has been shown to improve time to ischemia during exercise stress testing in patients with microvascular ischemia, although this effect was independent of any effects on coronary microvascular and diastolic function 3.
- Other treatments, such as sildenafil, quinapril, estrogen, and transcutaneous electrical nerve stimulation, have demonstrated benefits in small studies, while L-arginine, doxazosin, pravastatin, and diltiazem have shown no benefit 4.
Diagnostic Techniques
- Quantification of myocardial blood flow and flow reserve have improved diagnosis of coronary microvascular dysfunction, although important questions remain 5.
- The index of microcirculatory resistance (IMR) is an intra-coronary wire-based technique that provides a reliable and quantitative assessment of CMD and has been increasingly used as a preferred endpoint for evaluating CMD treatment strategies 6.
Current Understanding and Future Directions
- Coronary microvascular dysfunction is a complex condition with a spectrum of pathophysiology, and current understanding is still evolving 5.
- Further research is needed to address the lack of evidence-based data and to develop standardized definitions and assessment tools for CMD 2, 5, 4.
- Ongoing and future trials, such as the WARRIOR trial, will provide important insights into the treatment of coronary microvascular dysfunction and help to inform clinical guidelines 2.