Shall I deploy the stent?

An 88-years-old lady with unremarkable medical past health was admitted to medical ward for acute decompensated heart failure. She was stabilized with medical treatment and echocardiogram showed severe degenerative aortic stenosis with preserved left ventricular ejection fraction. Mean gradient across aortic valve was 60mmHg while the aortic valvular area was 0.52cm². There was moderate to severe mitral regurgitation. Coronary angiogram showed no significant obstruction in coronary arteries. STS score was 4% for mortality (intermediate risk category). The case was discussed in Heart team meeting and TAVI was considered a reasonable option for this patient.

TAVI workup including contrast CT study show a calcified tricuspid aortic valve with an annulus perimeter of 72mm and perimeter derived diameter of 22.8mm. Diameter of Sinus of Valsalva was around 28-29mm whereas mean Sinotubular junction dimeter was 26mm (Figure 1). Left coronary height was low (7.3mm) while the right coronary height was 14.1mm (Figure 2). Peripheral contrast CT showed reasonable size of iliofemoral vessel for most TAVI device and was free from significant disease. In view of high risk of left coronary obstruction secondary to low coronary height, coronary protection during TAVI procedure was planned (Movie 1).

Procedure was performed under general anesthesia. Transfemoral access was used. Balloon aortic valvoplasty was performed under rapid pacing (Movie 2). A 26mm self-expanding TAVI device was implanted with left coronary protection by meaning of parking an undeployed coronary stent in left coronary system (Movie 3). Post-dilation with a 22mm balloon was performed under rapid pacing for residual paravalvular leakage (Movie 4).

There was no residual gradient or leakage afterward. Intraoperative transthoracic echocardiogram showed subtle regional wall motion abnormality as compared to baseline image (Movie 5). However, coronary angiogram showed apparently good TIMI 3 flow (Movie 6, Movie 7) and hemodynamic remained stable after valve deployment. It was decided that the coronary stent not to be deployed and was retrieved. The case was extubated and sent to CCU for post-operative care.

Patient subsequently developed progressive shortness of breath and increasing respiratory failure which required Noninvasive positive pressure ventilator for support. Electrocardiogram also showed new T wave inversion over chest lead. Coronary obstruction was suspected (Figure 3) and she was sent to cath. lab for urgent relook coronary angiogram. It was not always easy to re-engage the coronary artery post TAVI especially with valve with high metallic frame from self-expanding valves. Tips and trips included using femoral access, half size smaller curve for Left main engagement and sometime nonselective injection (Figure 4). We used a 6Fr EBU 3.5 to come close to the cell overlying the left main and wired the coronary using “floating wire” technique (Movie 8). Ostial Left main was pre-dilated before a 3.5 stent was deployed in the ostial LMN in a “Chimney” fashion (Movie 9). Satisfactory angiogram was achieved after further post-dilation (Movie 10). Follow up echocardiogram show resolved regional wall motion abnormality with satisfactory aortic prosthetic valvular function (Movie 11). The patient was discharged uneventful later.

Coronary obstruction remained one of the nightmares in patient undergoing TAVI and was associated with high mortality and morbidity. It may be the last remaining factor that made TAVI a relative contraindication for patient with high risk of coronary obstruction. Several predictive factors included low coronary height, narrow Sinus of Valsalva, bulky and heavily calcified leaflet. It was previously belief that the obstruction mostly occurred immediately after valve implantation but there were increasing case reports that there was occasion of delayed occlusion. Coronary protection by means of putting an undeployed stent inside the coronary tree was the most commonly used method in cases of high risk of coronary occlusion. The stent can be immediately deployed if coronary obstruction occurred. Nonetheless, it may sometimes be difficult to judge when there was only partial obstruction like in our case.

It will be more frequent for us to encounter patient with suspected obstructive coronary artery disease which require coronary angiogram post TAVI as we move on to more “lower” risk patient categories. They are special consideration and technique to have a successful angiogram whereas special tips and tricks are required if PCI are contemplated. The details are outside the scope of this case discussion and reader can refer to the review paper by Matias B et al^ which describe the topic in great details.

^ Coronary Angiography and Percutaneous Coronary Intervention after Transcatheter Aortic Valve Replacement. Matias B. Yudi, Samin K. Sharma, Gilbert H.L. Tang and Annapoorna Kini. Journal of the American College of Cardiology Volume 71, Issue 12, March 2018