Because the ultimate therapy for the treatment of coronary artery disease has not yet been found, many opportunities still exist for effective therapies to combat atherosclerosis. So far, coronary stents hold the most promise for effectively treating an aging population with an increasing incidence of coronary artery disease.
Coronary stents are used to prop open partially blocked arteries and thus increase the flow of blood to the heart. It is increasingly used as an alternative to invasive CABG, which holds a greater risk for patients and results in longer recovery times. In addition, stents/angioplasty can be used in instances where the patient is deemed too much at risk for a more invasive procedure such as CABG.
Not only does percutaneous coronary intervention (PCI) present less risk for patients, initial costs are also less. While CABG patients experience less angina one year post-op, PCI is generally more cost-effective for low- and moderate-risk patients, according to SYNTAX study results presented in March 2009 at the ACC meeting. In the course of the study, researchers found that the quality of life for PCI patients outweighed CABG, but after the first year, CABG was clearly favored in higher-risk patients. Factored into the outcomes were an increase in repeat revascularization with PCI and an increase in stroke with CABG. The study compared PCI surgery incorporating the Taxus DES with CABG in 1,800 patients having either three-vessel or left-main coronary artery disease.
The SYNTAX results also showed that in low-risk patients, the total one-year costs for PCI averaged $32,292 versus $38,446 for CABG. In patients at moderate risk, PCI costs were $36,084 versus $39,973 for CABG. In high-risk patients, PCI costs were $39,765 versus $40,232 for CABG. (As part of that costs, each stent costs roughly $2,000.)
As seen in the SYNTAX study, PCI is not appropriate for all patients. A study published in the New England Journal of Medicine (Patrick W. Serruys, MD, et al., NEJM, 360: 961–972, February 18, 2009) showed that patients see little to no benefit from receiving a stent after an acute heart attack that closed an artery. The goal of the study was to find whether, with a complete blockage, there is any benefit to opening the artery. Earlier results from the Occluded Artery Trial (OAT) showed that four years after the heart attacks, the rate of death, heart failure or a subsequent heart attack was not reduced by a late attempt to remove the blockage. One year after surgery, patients were not any more active than those who did not undergo surgery but were given medical therapy instead. The 477 stented patients in the OAT trial did not gain the full benefit of angioplasty and stenting because they received treatment after the heart was irreversibly damaged and no longer able to significantly benefit from the oxygenated blood flow that angioplasty provides. In addition, the researchers concluded that CABG remains the standard of care for patients with three-vessel or left main coronary artery disease since the use of CABG, as compared with PCI, resulted in lower rates of the combined end point of major adverse cardiac or cerebrovascular events at one year.
Another study published in the March 5, 2009 edition of the New England Journal of Medicine furthered the debate over the appropriateness of open-heart surgery versus stenting for patients with complex coronary lesions. The latest findings from the SYNTAX trial, first reported in the fall of 2008 at the European Society of Cardiology annual meeting, provided mixed results—-proponents of CABG and proponents of PCI claimed partial victory. In CABG patients, death, myocardial infarction, stroke, or repeat revascularization at one year occurred significantly less frequently than in patients receiving PCI with a Taxus Express stent (the study was sponsored by Boston Scientific). The results reported by Patrick Serruys, MD, showed that the difference between the two methods of treatment did not meet the threshold for noninferiority, thus showing the superiority of surgery for patients with a three-vessel or left-main coronary artery disease. Meanwhile, proponents of PCI noted that the difference in the primary endpoint was driven by a higher rate of repeat revascularization (13.5% versus 5.9%), almost all with percutaneous intervention. In addition, CABG patients presented a nearly 4-fold increased rate of stroke (2.2% versus 0.6%). The two groups present at similar rates for all-cause death and the composite of death, MI, or stroke.
Even the study’s researchers did not agree on the final conclusions. Some physicians felt the results supported the use of PCI with stenting for perhaps up to one-half of patients with complex coronary lesions. Yet other physicians felt CABG should remain the standard of care for patients with left-main or three-vessel disease because PCI failed to meet the primary endpoint. Regardless, many physicians remain convinced that CABG would remain the standard of care for at least 80% of these patients. Two of the primary factors behind this belief our time and money—stent patients receive an average 4.6 stents with an average stent length of 86.1 mm. Many physicians are resistant to performing surgeries involving very long stents because of the time-consuming nature of these stents. In addition, hospitals may be reluctant to incur the costs inherent with these devices. Yet other physicians faulted the study design, stating that the hard endpoints of death, MI, and stroke should not have been combined with revascularization (the soft endpoint).
Alternatives to coronary stents for the treatment of occlusive disease are, for practical purposes, limited primarily to coronary artery bypass graft, but that procedure is also under continued development to minimize its invasiveness/trauma, improve clinical outcome and, overall, become more competitive with PCI. The development of minimally invasive approaches to CABG (mini-thoracotomy, MIDCAB, etc.) and the use of robotics — although hardly challenging from a competitive cost standpoint — may temper, but is unlikely to halt, the slow progression of PCI’s takeover of bypass graft procedures.
With varying degrees of potential, coronary artery disease is targeted for other device and non-device approaches including transmyocardial laser revascularization (TMR), gene therapies, HDL therapy, drug eluting balloons, the use of nanoparticles and other approaches. For some time to come, though, the opportunity in treatment of CAD remains strongly ensconced in the coronary stent market.
See "Worldwide Market for Drug-Eluting, Bare and Other Coronary Stents, 2008-2017". Report #C245, published May 2009.