Acute CAO is defined as a new complete or partial obstruction of one or both coronary ostia during a TAVI procedure [4]. This complication typically manifests as abrupt haemodynamic instability with rapid progression to cardiogenic shock and ventricular arrhythmias. The incidence of acute CAO during TAVR in native aortic valves is relatively low (< 1%) with a year mortality rate of 45.5%. In a large multicenter registry, the obstruction was most common on the left side (78.3%) [1, 5].

Pathophysiologically, the CAO occurs when the transcatheter heart valve (THV) displaces the underlying surgical or native aortic valve leaflets outward and obstructs the coronary artery ostia, directly or by sequestering the sinus of Valsalva at the sinotubular junction. However, CAO may be secondary to other less common mechanisms, such as the displacement of calcium towards the ostium.

Although the outcomes of patients undergoing TAVR are progressively improving because of the rapid evolution of technology, better imaging, increased operator experience, and the continuous iteration of devices, CAO remains a threatening complication with high rates of morbidity and mortality [6]. There are various predictors of CAO prior to valve placement such as the distance from the ostia, the degree of calcification, the distance from the sinuses. in such a situation, it highlights the importance of anticipating this complication. Therefore, some measures must be taken to prevent and treat coronary obstruction [2, 3].

Prevention strategies depend on the type of valve affected, whether it is native or bioprosthetic. Regarding bioprosthetic valves, the bioprosthetic aortic scallop intentional laceration to prevent iatrogenic coronary artery obstruction technique is a preventive measure (basilic technique). In native valve stenosis, there are currently 3 strategies to prevent coronary occlusion after TAVR: prophylactic guidewire, catheter, or stent intubation of at-risk coronary arteries.

In COPROTAVR registry, after a 3-year follow-up, the clinical outcome was generally favourable in patients treated with stenting. Preventive stent implantation across the coronary ostia was associated with good mid-term survival rates and low rates of stent thrombosis (cardiac mortality 7.8%, MI 9.8%, stroke 5.4%). In that trial, the patients protected with wires only had numerically more cardiac deaths compared to patients treated with stenting across the coronary ostia [7].

The rapidity of restoration of coronary blood flow appears to be an important determinant of outcome after CAO. Although a guide wire-only strategy its safe, it can be difficult to advance a coronary stent alongside the deployed THV (and displaced native leaflets) due to obstructing calcification or jailing of the safety wire between the aortic wall and the THV frame. A coronary balloon or stent premounted on the protective 0.014” guidewire can be parked distally in the coronary artery, retrieved proximally and deployed with rapid restoration of coronary flow in case of acute CAO [1, 5, 8]. However, stent jailing and difficulty in reaccessing coronary arteries must be taken into account as potential drawbacks of this technique.

Coronary access in this type of scenario is extremely challenging. The type of coronary revascularization in CAO depends on the anatomical characteristics of the aortic root and the perceived risk of CAO [8]. Two strategies have been implemented: the “chimney stent technique” coronary stenting across the coronary ostia with large protrusion in the aorta, and the “regular ostial stent technique” implying minimal protrusion of the stent in the aorta. In our case, we decided to perform the chimney technique due to the type of valve used and the anatomical characteristics of the patient [8,9,10].

The type of valve in patients with a high risk of obstruction has not yet been established. Due to the very complex anatomy and high risk of paravalvular leak, we decided to use an expandable balloon valve. One study suggested easier reaccess in Balloon expandible THV systems due to THV frame, and subsequently, opening the possibilty to do the chimney stent technique toward the aorta [10].

In our case, the high degree of calcification and the left ostium near the annulus were conditions for ostium obstruction at the time of valve release. In this context, provisional stenting prior to TAVR with a high risk of obstruction was an effective and safe strategy to achieve procedural success. It is therefore suggested that a protective coronary guide wire with a premounted coronary stent should be positioned distally in the coronary vessel prior to THV deployment.

Video 1: valve deployment.

Video 2: chimney technique.

Video 3: angiographic control of the left coronary arterial system.

Video 4: aortographic control.