Hot topics in interventional cardiology: Proceedings from the Society for Cardiovascular Angiography and Interventions (SCAI) 2019 Think Tank. Issue 4 (23rd August 2019) - Naidu, Srihari S.; Daniels, Matthew J.; Elmariah, Sammy; Garcia, Santiago; Klein, Andrew J.; Feldman, Dmitriy N.; Ing, Frank F.; Kavinsky, Clifford J.; Devireddy, Chandan; Mahmud, Ehtisham; Grines, Cindy L.; Henry, Timothy D.; et al.