We’re Living on the Edge: Perils of Post Dilatation of a Proximal Stent Edge Implanted in a Calcified Lesion near the Left Main Coronary Artery
Dr. Andre Lawrence TOJINO
Heart Institute, St. Luke’s Medical Center- Global City, Philippines
A 65-years old lady, with a history of hypertension, diabetes mellitus and angina pectoris, underwent coronary angiography. Angiogram revealed a severe stenosis in the proximal to mid left anterior descending artery (Figure 1). IVUS was done for pre planning and showed non-circumferential calcium in the proximal LAD (Figure 2). Scoring balloon was used for pre-dilatation of the proximal LAD. A 2.75 x 30mm DES was implanted in the mid-LAD and a 3.5 x 15mm stent was implanted in the proximal LAD at burst pressure. Post dilatation balloon inflation using a non-compliant 4.0mm balloon was done to further expand the stent according to IVUS proximal RVD. After balloon post dilatation in the proximal edge of the stent, the patient suddenly developed chest pain with significant ST-T electrocardiographic changes and hypotension. Subsequent contrast injection revealed Type A dissection of the LM artery up to the proximal LAD artery (Movie 1). IVUS revealed possible proximal LAD stent edge dissection (Figure 3). Immediately bailout angioplasty of the entire LM artery to proximal LAD artery using a 4.0 x 9mm stent was placed. After stent deployment there was resolution of chest pain and ST-elevation and resumption of hemodynamic stability. IVUS study confirmed satisfactory stent apposition and expansion. However, the ostium of the left circumflex artery was compromised. LCx was the serially dilated with 1.00mm and 2.0mm balloons. The final angiogram showed satisfactory result (Movie 2, Movie 3).
Iatrogenic left main artery dissection is a rare but potentially life-threatening event. It should be managed promptly, especially if the patient is suffering from hemodynamic instability. If the dissection is identified, further contrast injection should not be given to avoid enlarging the false lumen and propagating the dissection. In this circumstance, IVUS is a valuable tool to assess the mechanism and the extent of the dissection. If amenable to stenting, the dissection should be stented immediately to ensure antegrade flow. Prevention is always better than cure. Lesions should be well-prepared and the stent should be landed on relatively disease-free segment as much as possible. IVUS is useful to guide proper sizing of the stent but when using IVUS, sometimes down-sizing the stent a little may be advisable. Oversizing of the stent, deployment at high pressure and aggressive post-dilatation may all lead to stent edge dissection, especially if there is residual disease close to the stent.
In my opinion , dissection was caused by over sizing the stent in prox LAD followed by HP post-dilatation . Even if IVUS data suggesting 4.0 stent , I think it could be a good choice to a bit indersize the stent ( 3.5 mm) to prevent dissection . If post-stenting IVUS well suggest to post-dilate more the stent you are still in time to expand 3.5 stent to 4.0