Impact of renal denervation on patients with coronary microvascular dysfunction: study rationale and design.

Aims: Long-standing hypertension may cause an impairment in microvascular coronary circulation, which is involved in many different cardiac conditions. Renal sympathetic denervation (RDN) has been successfully proven as a valuable therapeutic choice for patients with resistant hypertension; moreover, the procedure looks promising in other settings, such as heart failure and atrial fibrillation, given its ability to downregulate the sympathetic nervous system, which is a recognized driver in these conditions as well as in microvascular dysfunction progression. The aim of this study is to explore the effect of RDN on coronary physiology in patients with ascertained coronary microvascular dysfunction and resistant hypertension.

Methods: This is a multicenter, prospective, nonrandomized, open-label, interventional study. Consecutive patients with resistant hypertension, nonobstructive coronary artery disease (NOCAD) and documented microvascular dysfunction will be enrolled. Patients will undergo RDN by Spyral Symplicity 3 (Medtronic Inc, Minneapolis, Minnesota, USA) and reassessment of coronary microvascular function 6 months after the procedure. Primary endpoint will be the difference in the index of microcirculatory resistance.

Conclusion: The IMPRESSION study seeks to evaluate if there is any pleiotropic effect of the RDN procedure that results in modulation of microvascular function; if observed, this would be the first evidence showing RDN as a valuable therapy to revert hypertension-related microvascular dysfunction.