AimsCatheter-based renal nerve ablation (RNA) using radiofrequency energy is a novel treatment for drug-resistant essential hypertension. However, the local endothelial and vascular injury induced by RNA has not been characterized, although this importantly determines the long-term safety of the procedure. Optical coherence tomography (OCT) enables in vivo visualization of morphologic features with a high resolution of 10–15 µm. The objective of this study was to assess the morphological features of the endothelial and vascular injury induced by RNA using OCT.Methods and resultsIn a prospective observational study, 32 renal arteries of patients with treatment-resistant hypertension underwent OCT before and after RNA. All pre- and post-procedural OCT pullbacks were evaluated regarding vascular changes such as vasospasm, oedema (notches), dissection, and thrombus formation. Thirty-two renal arteries were evaluated, in which automatic pullbacks were obtained before and after RNA. Vasospasm was observed more often after RNA then before the procedure (0 vs. 42%, P < 0.001). A significant decrease in mean renal artery diameter after RNA was documented both with the EnligHTN™ (4.69 ± 0.73 vs. 4.21 ± 0.87 mm; P < 0.001) and with the Simplicity® catheter (5.04 ± 0.66 vs. 4.57 ± 0.88 mm; P < 0.001). Endothelial-intimal oedema was noted in 96% of cases after RNA. The presence of thrombus formations was significantly higher after the RNA then before ablation (67 vs. 18%, P < 0.001). There was one evidence of arterial dissection after RNA with the Simplicity® catheter, while endothelial and intimal disruptions were noted in two patients with the EnligHTN™ catheter.ConclusionHere we show that diffuse renal artery constriction and local tissue damage at the ablation site with oedema and thrombus formation occur after RNA and that OCT visualizes vascular lesions not apparent on angiography. This suggests that dual antiplatelet therapy may be required during RNA.

Our study demonstrates for the first time that the number and type of vascular lesions as assessed with OCT did not predict the success of BP reduction after RDN. However, we observed a substantial decrease in office SBP in relation to the number of ablation points at 6 months.