The hybrid algorithm in treatment of coronary chronic total occlusions – MSWiA Lublin CTO 5-year registry

Introduction
Treatment of chronic total occlusions (CTO) despite improvement in techniques and results over the last years still seems to be limited to a small number of centres and operators. Application of the hybrid strategy may support further spread of CTO percutaneous coronary intervention (PCI) and increase procedural success rates.

Aim
Our single-centre prospective ongoing registry aims to provide details and results of recanalizations of coronary CTO performed according to the hybrid algorithm in a series of consecutive patients.

Material and methods
Between January 2015 and September 2019 the clinical and procedural data of CTO PCI procedures on consecutive patients were collected. Lesion complexity was assessed according to the Multicenter CTO Registry of Japan (J-CTO) score: 0 – easy, 1 – intermediate, 2 – difficult, ≥ 3 – very difficult and PROGRESS score. Strategies applied were classified as: antegrade wire escalation (AWE), antegrade dissection and re-entry (ADR), retrograde wire escalation (RWE) and retrograde dissection and re-entry (RDR). Angiographic success was defined as < 30% residual stenosis with TIMI 3 flow. Angiographic and clinical complications were reported.

Results
Two hundred sixty-six patients were included and 285 procedures were performed in total. Success rate was 87.7% (calculated per procedure) and 92.5% (calculated per patient). Four patients underwent successful staged double CTO recanalization. Fifteen patients out of 31 primary failures underwent a second attempt with a 73% success rate (11/15). Fifty-two patients (18.2%) were referred for a second attempt from other institutions. Mean J-CTO score was 2.6 (13 cases with J-CTO of 0, 41 cases with J-CTO of 1, 80 cases with J-CTO of 2, and 151 cases with J-CTO ≥ 3) and the success rate was respectively 92.3%, 95.1%, 91.3% and 83.4%. Higher complexity of occlusion required a higher number of applied strategies including retrograde access in over a quarter of cases. Complete revascularization was achieved in 215 (75.4%) cases. In-hospital MACCE rate was 3.5% – 1 patient died due to acute kidney injury complications, 9 (3.2%) patients sustained myocardial infarction (1 STEMI due to side branch occlusion). All 7 (2.5%) coronary perforations (Ellis 1 and Ellis 2) were treated conservatively and we recognised 10 (3.5%) cases of acute kidney injury (one dialysis).

Conclusions
The hybrid algorithm in CTO PCI can be successfully applied with good early results and low complication rates. Higher complexity CTOs require more procedural strategies with a significantly lower success rate in very difficult cases.