Incomplete coronary sinus reducer endothelialization as potential mechanism of clinical failure.

The number of patients suffering from refractory angina is constantly increasing. Moreover, these patients are considered at higher risk for new hospitalizations and increased incidence of adverse cardiac events. The coronary sinus reducer was recently introduced as a new therapeutic option in patients with refractory angina and no possibilities for coronary revascularization. However, a consistent percentage of patients, ranging from 15 to 30%, reports no clinical benefits after coronary sinus reducer implantation. The reasons for this lack of effectiveness are at present unknown. We suggest here a possible explanation to this phenomenon.