Coronary stents have revolutionised the management of CAD. Stents are metallic scaffolding devices that help keep the atherosclerotic plaque plastered within the coronary arterial wall.Thus it gained the name angioplasty. Stents have aradial strength that exerts a constant force on the plaque . Since metals are unfriendly partners for coronary artery , we need to have minimum metal within the coronary artery.The stent struts weave around the lumen generally the stento/ artery area ratio should be as less as possible (15%).
But this has a trade off .The uncovered area of plaque tend to project into the lumen .This is many times not significant.But can be a problem if the plaque is very soft and bulk of the lipid core may reenter the lumen.this event is called plaque prolapse.
What is the time taken for plaque to prolapse ?
Generally it is late event.But it can happen immediately after the procedure also.
Which type of lesions are more likely to have plaque prolapse ?
Eccentric and complex lesions especially with overhanging edges are prone for prolapse
What is the sequale ?
It can be benign.If there is a erosion due to stent struts can precipitate an ACS.It progresses into instent restnosis in many.
What is the angiographic appearnce ?
Angiographically it often appears as luminal irregularity withi stented segment .
Many times , it may appear as a filling defect also.
Is there any specific issues in plaque prolapse in drug eluting stents ?
Coornary artery is not drugged uniformly by the drug eluting stents.In fact contact lines of metalic struts , through it’s micropore oozes the drug with polymer.Pathological studies have revelaed non homogenous drug penetration and resultant irregularity on the plaque surface.This could amplify the plaque penetration preferentially in few areas.
How to manage plaque prolapse ?
It should be managed as any other instent restenosis.Plaque resection with atherectomy devices has not solved the problem to the desired levels.A second stent is the most common approach advocated by the cardiologists.(Whic is not ideal though !)
Dr.S.Venkatesan MD 