Dear colleagues,

Percutaneous coronary intervention for chronic coronary syndrome with atherosclerotic stenosis is declining; however, the benefit of catheterization for the acute coronary syndrome is unquestionable. Coronary artery disease without significant stenosis has recently received attention as myocardial infarction with nonobstructive coronary arteries or ischemia without obstructive coronary artery disease. Therefore, identifying the cause or endotype using coronary function tests may be important.

WATCHMAN^TM in arrhythmias, transcatheter aortic valve implantation for the aortic stenosis, and MitraClip for mitral regurgitation in the area of structural heart disease have been used in a growing number of cases. In congenital heart diseases, atrial septal defect treatment is a matter of course, but the treatment of patent foramen ovale is becoming more widespread. Developments in these areas are remarkable.

Therefore, this special issue will collect a wide range of original studies and review articles on cardiac catheterization and treatment at present to help understand the current and future directions and issues in this field.

High priority will be given to the following topics:
• acute coronary syndromes, including myocardial infarction with non-obstructive coronary artery disease; 
• chronic coronary syndrome, including ischemia with non-obstructive coronary artery disease; 
• intracoronary imaging; 
• catheter interventions for structural heart disease.

Dr. Hiroki Teragawa and Dr.  Hiroki Ikenaga

Guest Editors