It is recommended that if stent malapposition is detected, further stent expansion should be considered during the intervention if there is stent under-expansion. Stent under-expansion is defined as an MSA of the proximal segment <90% of the proximal reference lumen area or an MSA of the distal segment <90% of the distal reference lumen area.1
1Lancet 2016; 388:2618-28.
Figure I. An example of a malapposed stent which met criteria for stent under-expansion. A decision was made to further expand the stent with multiple balloon inflations. The following image demonstrates the same vessel with significantly improved apposition of the stent struts.