Angioplasty, when introduced in 1977, relied solely on balloons for dilatation of coronary arteries. While this in itself revolutionized the treatment of CAD, the advent of bare metal stents caused a drastic expansion in the type of patients undergoing the procedure. However, as problems of in-stent restenosis soon became apparent, alternative techniques including atherectomy and brachytherapy were introduced, only to be followed by the more successful drug-eluting stents. Our report provides a snapshot of this evolution and its impact on procedural outcomes over a twenty-year period in two large, prospective, multicenter registries of clinical practice in North America. These findings are especially noteworthy given that previous reports of temporal trends have been restricted to specific technology eras (4
) or are single-center experiences (6
PCI use in contemporary practice has expanded to include more patients with severe comorbidities, acute coronary syndromes and multivessel disease. The lower rates of prior MI in the more recent waves, especially in light of the concomitant trend of higher rates of PCI performed for acute coronary syndromes over time, is noteworthy. While these trends could potentially be a reflection of the revised guidelines favoring primary PCI instead of fibrinolysis in acute syndromes, they are also in keeping with the reported decline in annual rates of recurrent infarctions in community-based settings (10
). Attempted lesions, in the recent waves, were more often determined to be calcified or thrombotic, when compared to the early cohorts. These trends, however, could be a reflection of improved or better imaging techniques over time, rather than a true increase in these characteristics. The concept of complete revascularization (CR), which stemmed from early CABG studies, appears to have given way to a more selective approach over time as evidenced by the predominance of single vessel attempts in multivessel disease patients. One plausible explanation is the greater use of PCI for acute conditions where functional (and not anatomic) revascularization is of priority. A prior report from this Registry (11
) has also shown that patients with multivessel disease, in whom CR was unachievable, were older with more comorbidities and lower ejection fraction, when compared to those in whom CR was achieved or selective revascularization was the method of choice.
Temporal trends in procedural safety
The present report demonstrates a dramatic improvement in procedural outcomes (high success rates and reduced need for in-hospital bypass surgery) with the advent of stents. Furthermore, even within the stent era, there is a significant reduction in the initially high rates of dissections and abrupt closures. While this certainly reflects the huge impact of technology, it also underscores the importance of operator training and better techniques. Improvements in in-hospital outcomes are also seen to extend over one year (lower rates of death/MI and CABG) and are congruent with previously published reports (4
). Nonetheless, the higher crude mortality rates in the Dynamic Registry, in the overall cohort and by primary indication, is reflective of sicker profile (older patients, more comorbidities, greater disease burden) of patients enrolled in these waves. Prior comparison of one year outcomes between patients undergoing PCI for stable versus unstable angina showed little change in mortality rates in the latter cohort over the past 16 years (12
). In another report of 2,839 patients with complex lesions (defined as a lesion showing evidence of thrombus, calcification, bifurcation or ostial location, or chronic occlusion), both in-hospital and one year mortality rates were higher, compared to attempts on simpler lesions (13
). Moreover, reports of stent-thrombosis with DES use has led to concerns of use and timing of dual antiplatelet therapy (14
) and the need to focus on cause-specific, rather than overall, mortality (15
). Thus, in spite of the marked overall improvement in the field, certain high-risk subsets continue to pose major challenges and warrant closer attention (16
Temporal trends in Effectiveness
Development of devices in PCI was primarily aimed at reducing the need for repeat interventions, be it surgical or percutaneous. Our cohorts are representative of key devices available in the respective time periods – PTCA Registry (balloons), wave 1(early use of BMS), wave 2 (uniform use of BMS), wave 3 (brachytherapy), wave 4 (early use of DES), and wave 5 (established use of DES). The sustained
reduction in the need for repeat revascularization, therefore, truly underscores the progress made in the field. The greater need for ‘early’ repeat PCI paralleling the precipitous drop in CABG rates, small sample size notwithstanding, deserves particular mention. We believe that while in the pre-stent era, CABG was a more powerful option in the event of failed index PCIs, the advent of stents caused a shift in favor of using PCI for repeat revascularization in these cases. Alternatively, PCI has been increasingly performed in sicker patients with multivessel disease but using a selective treatment strategy while achieving 100% procedural success (see Supplemental Table
). The increased use of early PCI, therefore, may be a related fall out of this greater disease burden.
Secondary medical therapy in PCI
Pharmacological therapy in atherosclerosis has undergone major improvements over time and their salutary effects in the setting of coronary revascularization have been well-documented (17
). More recently, a comparison of an initial strategy of PCI and optimal medical therapy versus medical therapy alone, in 2287 patients with stable CAD, revealed no difference in the rates of the composite endpoint of death and nonfatal MI (21
). While this highlights the notable progress in the field of medical therapy, it also reiterates the need for systemic management of atherosclerosis. After all, PCI treats only angiographically visible stenoses and not the underlying disease mechanism responsible for new lesions and resultant ischemic events. To this end, the increase in the discharge use of evidence-based therapy (aspirin, beta blockers, cholesterol lowering agents, and antiplatelet therapy), as observed in our report, is encouraging and reflects an improved awareness of the importance of secondary prevention.
Although limitations inherent to use of a registry database must be acknowledged, enrollment of consecutive patients with no exclusion criteria permits representation of real world practice and allows for the timely evaluation of safety and effectiveness. The majority of centers participating in the registries were medium to high volume hospitals and more often academic centers, thus limiting the generalizability of our findings. The primary objective of this analysis was to assess temporal trends using the ‘wave’ variable as marker of change in both technology as well as secondary therapy in that particular time period. Therefore, we did not specifically adjust for or evaluate these factors in multivariable models. Also, ascertainment of data was refined in each wave to incorporate prevailing concerns in the field. Thus, only those variables available in all cohorts were considered for multivariable analysis. Information on peri-procedural myocardial enzymes was lacking in both the registries, thus, limiting our ability to assess related impact on events.