Tercera Etapa: Condición de Tráfico afectado

The field of coronary intervention has expanded dramatical- ly over the past decade and will continue to evolve over the next several years. New directions will focus on strategies that will further improve procedural safety, reduce the recur- rence rate after PCI, and expand the procedure to more com- plex anatomic subsets. Clinical acceptance of these tech- nologies will be based on demonstration of safety and effica- cy over conventional therapies in randomized clinical stud- ies. Several novel strategies are summarized below.

Because the widespread use of stent implantation has less- ened the risk of need for emergency bypass, future clinical research will focus on remaining obstacles that decrease pro- cedural success or increase risk. Chronic total occlusion remains a stubborn problem. New devices such as the Frontrunner catheter and new ultrastiff guidewires show some promise in improving procedural success; however, new approaches are needed.

Degenerated vein graft disease remains a high-risk subset. The SAFER trial (255) has demonstrated that distal protec- tion with a balloon occlusive device with intraprocedural aspiration decreases procedural risk. Similarly, a number of distal filter devices are undergoing active testing (254). The results of one such multicenter trial comparing a filter-based catheter with a balloon occlusive and aspiration device showed similar results for MACE at 30 days (254). In spite of these approaches, these procedures are still associated with MACE event rates of 8% to10%. More research is still needed in this area. The use of distal protection devices in settings other than degenerative vein graft disease requires further study. For example, initial studies in primary PCI suggested a benefit with the FilterWire™; however, subse- quent trials with the GuideWire have failed to show any ben- efit, instead showing poor outcomes in this setting. Thus, fur- ther research is needed before this technology is adopted for use beyond degenerative vein graft disease.

Dramatic advances have been made in the treatment of restenosis. Although the oral agents tranilast (921) and folic results from randomized trials (levels of evidence A and B)

are used to estimate the outcomes of each decision tree branch within the decision-analytical model, for example, using data estimating the restenosis rate after uncomplicated coronary stenting of a single, simple lesion. Cost-effective- ness analyses have been used to compare medical therapy with PTCA with CABG (914), balloon angioplasty with coronary stenting (915,916), and routine coronary angiogra- phy after acute MI with symptom-driven coronary angiogra- phy (917).

In patients with severe angina, normal LV function, and single-vessel disease of the LAD, the cost-effectiveness ratio for PTCA, directional coronary atherectomy, or coronary stenting that can be expected to provide a more than 90% success rate with a less than 3% major acute complication rate is very favorable (less than $20 000 per QALY) com- pared with medical therapy (914). The rating also applies to patients with symptomatic angina or documented ischemia and 2-vessel coronary disease, in whom percutaneous coro- nary revascularization can be expected to provide a more than 90% success rate with a less than 3% major acute com- plication rate. In patients with 3-vessel coronary disease who have comorbidities that increase the operative risk for CABG surgery, PCI that is believed to be safe and feasible is rea- sonably acceptable ($20 000 to $60 000 per QALY). In patients in the post-MI setting, a strategy of routine, non–symptom-driven coronary angiography and PCI per- formed for critical (greater than 70% diameter stenosis) cul- prit coronary lesions amenable to balloon angioplasty or stenting has been proposed to be reasonably cost-effective in many subgroups (917).

In patients with symptomatic angina or documented ischemia and 3-vessel coronary disease, for which bypass surgery can be expected to provide full revascularization and an acute complication rate of less than 5%, the cost-effec- tiveness of PCI is not well established. Although PTCA for 2- and 3-vessel coronary disease appears to be as safe as but initially less expensive than CABG surgery, the costs of PTCA converge toward the higher costs of bypass surgery after 3 to 5 years (918,919). Thus, whereas PTCA or CABG surgery has been shown to be cost-effective compared with medical therapy, there is no evidence for incremental cost- effectiveness of PTCA over bypass surgery for 2- or 3-vessel coronary disease in patients who are considered good candi- dates for both procedures. For patients with 1- or 2-vessel coronary disease who are asymptomatic or have only mild angina, without documented left main disease, the estimated cost-effectiveness ratios for PCI are greater than $80 000 per QALY compared with medical therapy and are thus consid- ered less favorable.

The initial mean cost of angioplasty was 65% that of sur- gery, but the need for repeat interventions increased medical expenses so that after 5 years, the total medical cost of PTCA was 95% that of surgery ($56 225 vs $58 889), a significant difference of $2664 (Pequals 0.047). Compared with CABG, PTCA appeared less costly for patients with 2-vessel disease but not for patients with 3-vessel disease.

rial infusion of marrow-derived stem cells (926) and direct injection of skeletal muscle–derived myoblasts (927) for myogenesis. Studies to date were performed in patients with severe angina; thus, it is uncertain how this technology might apply to other subsets of patients with coronary disease (e.g., acute coronary syndromes, ischemic cardiomyopathy), and rigorous, blinded evaluation of these approaches must occur.

STAFF

American College of Cardiology

Christine W. McEntee, Chief Executive Officer Katherine D. Doermann, Senior Specialist, Practice

Guidelines

Kristina N. Petrie, MS, Associate Director, Evidence-Based Medicine

Dawn R. Phoubandith, MSW, Associate Director, Practice Guidelines

Peg Christian, Librarian, Knowledge Management

American Heart Association

M. Cass Wheeler, Chief Executive Officer

Rose Marie Robertson, MD, FACC, FAHA, Chief Science Officer

Kathryn A. Taubert, PhD, FAHA, Senior Science Advisor

Society for Cardiovascular Angiography and Interventions

Norm Linsky, Executive Director

Wayne Powell, Senior Director, Advocacy and Guidelines acid have proven unsuccessful, other catheter-based strate-

gies have dramatically decreased restenosis risk. Brachytherapy (for ISR), rapamycin-eluting stents, and PES have been extremely effective. Subgroups such as diffuse ISR and insulin-dependent diabetes mellitus will require fur- ther study. Other therapies, such as photodynamic therapy, cryotherapy, and therapeutic ultrasound, remain interesting but unproven approaches to treat restenosis.

In patients with refractory angina who have no vessels suit- ed for revascularization, a number of new therapies are being tested. Enhanced external counterpulsation appears to decrease symptoms (922). Treatment with fibroblast growth factor by an intracoronary approach also shows promise (923). Percutaneous laser transmyocardial revascularization has shown mixed results. The PACIFIC trial (Potential Class Improvement From Intramyocardial Channels) putatively demonstrated some benefit of percutaneous laser transmy- ocardial revascularization, but the major limitation of that study was that it was not placebo-controlled; thus, after its failure to address potential concerns, general consensus attributes the results in PACIFIC to a placebo effect. Also, in PACIFIC, diverse outcomes tended to be higher with laser therapy (924). Although the randomized, double-blind BELIEF trial (Blinded Evaluation of Laser PMR Intervention Electively For angina pectoris) of 82 patients appeared to show some benefit of percutaneous laser trans- myocardial revascularization versus sham procedure on angina class and quality-of-life measures, the results were inconclusive given the small size of the study (925). To date, data are insufficient for FDA approval of percutaneous laser therapy. A new frontier has been opened with the intra-arte-

APPENDIX 1.ACC/AHA/SCAI Committee to Update 2002 Guidelines for Percutaneous Coronary Intervention—Relationships with