Dynamic Evaluation of Coronary Intervention

BACKGROUND:

In 1977, the selective coronary catheter which was developed and introduced by Dr. Andreas Gruentzig and his colleagues in Zurich, was first proposed as a therapeutic tool for the dilatation of obstructions in the coronary arteries. Initial reports on the technique were enthusiastic and many teams began to evaluate the procedure. In March 1979, the National Heart, Lung, and Blood Institute initiated an interim registry on PTCA to expedite the evaluation of the technique and in December 1979 released a Request for Proposals to established a formal registry. A contract was awarded in August 1980 to the University of Pittsburgh.

The 1979 registry collected cases prospectively beginning in 1979 as well as retrospectively back to the introduction of the procedure in 1977. To participate in the registry, centers were required to submit data on all patients who had a guide catheter introduced as the first step in the angioplasty procedure. From 1979 to 1982 3,248 patients were entered from 105 clinical sites and in 1982, the registry stopped entering new cases and shifted its effort to follow-up. Sixteen of the largest centers participated in the five year follow-up. During the follow-up period, the range of patients expanded greatly with technologic advances and clinical experience. The registry was reopened in 1985 to confirm and document changes in angioplasty techniques and results. Methods of data collection in the new registry were the same as in the old. Within ten months, 2,094 new patients were enrolled.

The PTCA III or NACI Registry was established in 1990 to follow revascularization devices or methods other than PTCA. Utilization of PTCA experienced an explosive growth since it was first introduced. However, despite this rapid growth in technological improvements and techniques, balloon angioplasty is not universally successful. Problems relate to failure to cross chronic total occlusions, failure to successfully dilate elastic lesions, intimal dissection and abrupt closure which leads to emergency surgery, and most particularly, restenosis of the dilated segment. In the late 1970s, diverse technologies were developed in an attempt to counter the problems plaguing coronary angioplasty. These technologies include: mechanical devices for crossing total occlusions; atherectomy catheters; abrasive athero-dispersion devices; intracoronary stents; ablative lasers; hot-tip lasers, and laser balloon dilation techniques. Each of the above device categories entered clinical testing. However, these devices were in a state of flux. Moreover, these devices were utilized in different clinical settings, with different definitions of success and complication rates and different follow-up regimens. Therefore, it was difficult to judge the relative efficacy of any single device in comparison to standard PTCA. The need to establish a mechanism capable of evaluating each device was, therefore, of practical importance from a clinical and investigational standpoint. The primary purpose of the registry was not to compare devices but to follow simultaneously the progress of multiple devices in a parallel fashion, using common methodologies and definitions in their early clinical usage.

The NHLBI "Dynamic Registry," which for years has provided objective, "real world" assessment of the changing practice of percutaneous coronary intervention (PCI) was extended through June 2007. In just 25 years, the practice of PCI has evolved from balloon angioplasty-to directional and rotational coronary atherectomy-to bare-metal stents-to new interventional devices including lasers and therapeutic ultrasound-to intracoronary radiation-to distal protection devices-and most recently to the widely anticipated introduction of drug-eluting stents. These evolutions, which have been accompanied by a 150% increase in PCI procedures in the U.S. in the past 8 years alone, necessitate ongoing evaluation in diverse clinical practices across all patient subgroups, as many promising results observed initially in clinical trials are not realized, or are only marginally realized, in clinical practice. The multi-center Dynamic Registry fulfills this mission, and is the only formal registry of consecutive PCI-treated cases that captures both in-hospital and long-term patient outcomes, while characterizing initial procedural strategy and outcome in great detail on the patient and lesion level.