Case reports are defined as the scientific documentation of a single clinical observation. They are considered to be at the bottom of the hierarchical ladder of clinical research. Most journal ranking hierarchies do not list case reports at all, but case reports are important studies that often lead to advancing medical scientific knowledge – especially of rare diseases. While there are clear limitations to the methodology of case reports, the observation of a single patient can add to our understanding of etiology, unusual clinical syndromes, clinical management, outcome, complication, or unusual presentation of common diseases, treatment of particularly rare diseases, and potential rare side effects of the treatment.

The history of medicine owes a debt to Dr. William McBride [ ] and Dr. Widukind Lenz [ ], who published independently in case reports their observations linking the usage of thalidomide during pregnancy to congenital malformations. Those case reports revealed one of the largest manmade medical disasters in history. In cardiology, the era of heart transplantation was initiated by Barnard’s case report of the first successful transplantation in the South African Medical Journal on December 16, 1967 [ ], and the ubiquitous percutaneous coronary intervention was the consequence of the case report of 5 patients as a Letter to the Editor in The Lancet by Andreas Gruntzig on February 4, 1978 [ ].

In interventional cardiology, case reports are very important. Reporting cases has an additive value that can be missed, or can go undetected, in other publications. Case reports can emphasize technical aspects of intervention and equipment in a way that is similar to a live case or a case presentation in a conference. In case reports, new procedural techniques can be described with all the steps and equipment necessary. This is a very important resource that can be of great help when a reader might encounter a similar challenging case. For example, I personally learned from case reports several useful techniques for vascular closure such as: “double wire” angio-seal closure technique for large bore access [ ], parallel suture technique with ProGlide [ ], or techniques for Impella removal while preserving arterial access [ ]. In the current era, all journals have online access with videos that illustrate and simplify the understanding of complicated procedures. On top of the advantage described above, case reports are among the best ways for authors to get started in scholarly writing, and they can provide learning opportunities in the practice of scientific writing as well as a chance to get chief authorship.

Case reports have many limitations as well. Sometimes they can raise false alarms. In interventional cardiology, they may lead to an inexperienced operator trying to mimic a method or implementing the technique in a different clinical case, which could be harmful. Many case reports are also subject to bias and tend to report successes rather than failures.

In recognition of the value of case reports, we are pleased to dedicate this issue of Cardiovascular Revascularization Medicine to case reports on various topics. They include unusual presentations of acute coronary syndrome, complex coronary interventions, structural and endovascular procedures, complications, and new innovations. I am sure this special edition of reports of various complex cases will prove helpful for the reader/operator in treating patients. We invite you to read them and cite them!