Percutaneous Transluminal Coronary Angioplasty (PTCA) Registries I, II, and III and the Dynamic Registry

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.

DESIGN NARRATIVE:

The second registry established five year mortality and morbidity rates for the 1985-1986 cohort as well as determined functional status and subsequent revascularization. Secondary goals included estimating rates of clinically apparent restenosis for all patients and for important subgroups, determining recurrence of symptoms, seeking predictors of long-term response to PTCA overall and in subgroups, determining PTCA success angiographically, and providing background information for the NHLBI clinical trial, Bypass Angioplasty Revascularization Investigation (BARI). Sixteen center participated in the second registry. Patient follow-up was performed independently of medical care visits. The National Death Index was searched for patients who were judged lost to follow-up. Each center determined angiographically the results of angioplasty but also sent all cineangiograms to a central laboratory.

The third registry, NACI, was designed to gather information on the use of three types of intervention technologies other than PTCA. The interventional techniques were loosely grouped into several categories such as atherectomy, stents, and laster methods. Patients were contacted by telephone at six weeks, six months, and a year. The centers performed a treadmill test and a repeat angiogram at six months. To be investigated, a technique must have been used at two or more centers and a center must have used the intervention in at least five patients. Following acceptance into the registry for a technique, the clinical site admitted alll subsequent patients consecutively. Results were analyzed in batches of fifty, examining both patients and lesions as analytic units. The primary endpoint was reduction of a target lesion by at least 20 percent and to less than 50 percent final diameter stenosis without major complications. Secondary endpoints common to all devices included major events and additional events, health status at follow-up, and patency status at six months. In addition, there were secondary endpoints specific to the device under study. In 1993, an independent Angiographic Core Laboratory was established for the NACI under R01HL49527.

Beginning in July 1997, the PTCA Registry and the NACI registry were renewed through June 2002 under U01HL33292. The purpose of what could be considered a fourth registry was to conduct a dynamic evaluation of new device usage patterns, as well as intermediate and follow-up outcomes in patients undergoing percutaneous transluminal coronary revascularization. Three waves of 2,000 consecutive patients each, 18 months apart, were entered from 13 participating clinical sites and followed for one year. The design was such that women and minority patients were oversampled. The clinical and angiographic characteristics of patients undergoing a coronary intervention procedure were described. There was a registration of frequency of different procedures used, such as conventional balloon, new devices and combinations of devices to provide information about the value of added new devices. Initial success rates and complications were evaluated. There was one year follow-up of clinical events and subsequent procedures and assessment of one year symptom status including clinical re-stenosis and durability of these interventions. Clinical and anatomic criteria influencing choice of angioplasty strategies were identified. Procedural outcomes were examined in subgroups, including women, African Americans, diabetics, patients with prior revascularization, and those over 75 years of age. Sub-studies of cost and cost-effectiveness of coronary interventional procedures were developed.

The Dynamic Registry was extended through June 2007 to a) continue annual patient follow-up from 3 to 5 years for the 2020 Wave 2 Registry patients who underwent PCI in 1999 (characterized by frequent stent use of varying types); b) perform one-year follow-up on the 2124 Wave 3 Registry patients, and annual follow-up to 5 years on the approximately 150 Wave 3 patients who underwent PCI in 2001/2002 and received the then novel intracoronary radiation therapy; c) enroll and follow annually for 4 years a Wave 4 of 2000 Registry patients who will undergo PCI following the introduction of the much awaited drug-eluting stents into clinical practice; d) enroll and follow for at least one year a Wave 5 of 2000 Registry patients who will undergo PCI at a time when subsequent generations of drug-eluting stents have penetrated clinical practice. As successfully accomplished with all previous waves of patient enrollment, women and minorities will continue to be oversampled in the Registry, as an important study aim is to investigate potential health disparities in clinical practice and outcome by gender, and race/ethnicity, while controlling for socioeconomic status. Finally, the investigators will coordinate a cost effectiveness analysis on the use of drug-eluting stents in a same of Wave 4 registry patients supported through a separate source of funding, and pilot test new data collection forms in the setting of peripheral arterial disease catheter-based interventions.

Another extension was received in 2007 with funding concluding in 2012. This study involves the long-term follow-up of participants recruited in 2004 (Wave 4) and 2006 (Wave 5) across 16 medical centers. All subjects will be followed for a total of 5 years and participants from Waves 4 and 5 have already been followed for 3 and 1 years, respectively. Follow-up will be conducted via annual telephone interviews and these data will be used to track the incidence of long-term outcomes. All identified deaths and myocardial infarctions will be reviewed by an adjudication committee to (1) classify cause of death and (2) determine whether or not the myocardial infarction is related to stent thrombosis. The research aims are to: (1) Compare 5-year mortality and myocardial infarction between participants treated with drug eluting stents (DES) versus bare metal stents (BMS) overall, within "high-risk" subgroups, and by "off-label" stent use; (2) Evaluate cardiac and non-cardiac causes of mortality among participants treated with DES versus BMS; (3) Compare 5-year mortality and repeat revascularization by the sirolimus-eluting versus paclitaxel-eluting stent overall, within "high-risk" subgroups, and by "off-label" stent use; and (4) Investigate mechanisms that contribute to stent thrombosis, myocardial infarction, death, and repeat revascularization in participants treated with BMS and DES. In summary, by extending the active NHLBI Dynamic Registry, we will analyze long-term outcome data on several thousand PCI participants treated with BMS and DES.