Diseases of the Coronary Microcirculation: Diagnosis and Treatment

BACKGROUND

Coronary microvascular dysfunction (CMD) comprises a variety of pathogenic mechanisms that impair the microcirculation of the heart. Clinical studies have shown that 30-50% of patients suffering from myocardial ischemia without significant coronary artery stenosis have CMD. The disease is associated with ele - vated mortality and poor quality of life. Whenever a patient presents with symptoms of angina pectoris and no underlying disease is detected by the usual methods, CMD should be considered a possible cause.

METHODS

This review is based on publications retrieved by a selective search in PubMed and on current international guidelines and recommendations of specialty societies.

RESULTS

The diagnosis of CMD is based on objective evidence of a microvascular origin of symptoms. The guidelines contain a class IIa recommendation for invasive coronary flow reserve and microvascular resistance measurements. Noninvasive tests such as positron emission tomography and cardiac magnetic resonance imaging are less accurate and are given a class IIb recommendation. No highquality therapeutic trials are available to date, and the treatment of CMD is thus based on that of chronic coronary syndrome. Lifestyle modification is performed to reduce risk factors. Patients with an abnormal coronary flow reserve or elevated microvascular resistance can be treated with an ACE inhibitor or angiotensin receptor blocker. Beta-blockers and calcium channel antagonists can relieve angina pectoris. Statins lower the LDL level and have positive pleiotropic effects. First-line treatment can be supplemented with further medications.

CONCLUSION

Approximately 25% of patients with CMD have symptoms that do not respond to intensive treatment with the currently available modalities. New treatments, including interventional therapies, are being studied. Their long-term benefit remains to be assessed and compared to that of the existing methods.

Comparison of Coronary Intravascular Lithotripsy and Rotational Atherectomy in the Modification of Severely Calcified Stenoses

Debulking techniques are often necessary for successful lesion preparation in percutaneous coronary intervention. The aim of this study was to compare plaque modification of severely calcified lesions by coronary intravascular lithotripsy (IVL) with that of rotational atherectomy (RA) using optical coherence tomography (OCT). ROTA.shock was a 1:1 randomized, prospective, double-arm, multicenter noninferiority trial designed to compare final minimal stent area after IVL with RA for lesion preparation in percutaneous coronary interventional treatment of severely calcified lesions. On the basis of OCT acquired before and immediately after IVL or RA in 21 of the 70 patients included, we performed a detailed analysis of the modification of the calcified plaque. After RA and IVL, calcified plaque fractures were present in 14 of the patients (67%), with a significantly greater number of fractures after IVL (3.23 ± 0.49) than after RA (1.67 ± 0.52; p < 0.001). Plaque fractures after IVL were longer than after RA (IVL: 1.67 ± 0.43 mm vs RA: 0.57 ± 0.55 mm; p = 0.01), resulting in a greater total volume of the fractures (IVL: 1.47 ± 0.40 mm³ vs RA: 0.48 ± 0.27 mm³; p = 0.003). Use of RA was associated with a greater acute lumen gain than was use of IVL (RA: 0.46 ± 0.16 mm² vs IVL: 0.17 ± 0.14 mm²; p = 0.03). In conclusion, we were able to show differences in plaque modification of calcified coronary lesions by OCT: although RA leads to a greater acute lumen gain, IVL induces more and longer fractures of the calcified plaque.