There have been few areas in medicine that have seen such rapid growth as interventional cardiology. This is one of the most studied and investigated fields; yet, simultaneously, technology is being utilized and pushed into uncharted indications. As such, interventional cardiology now encompasses nearly all aspects of the cardiovascular system, including cerebrovascular disease, valvular heart disease, coronary artery disease and aneurismal disease.
Despite incredible advances in technology as well as technique, many of the less invasive procedures that are currently performed have failed to demonstrate improved survival when compared with standard therapy. Some examples include carotid artery stenting, endovascular abdominal aortic aneurysm repair, and percutaneous coronary interventions for coronary artery disease.
Carotid artery stenting has rapidly gained favor as an approach to treating carotid stenosis. However, multiple studies have not been able to show a consistent benefit (and, sometimes even noninferiority) when compared with open surgical therapy. Two recent trials – the randomized Endarterectomy versus Angioplasty in Patients with Symptomatic Severe Carotid Stenosis (EVA-3S) trial and the Stent-Protected Angioplasty versus Carotid Endarterectomy in Symptomatic Patients (SPACE) study Citation[1,2] – evaluated the safety and efficacy of carotid stenting compared with traditional carotid endarterectomy. Although many have found potentially significant flaws within both of these trials, they have called into question the role of carotid stenting in the management of patients with both symptomatic and asymptomatic carotid artery disease. Patients with asymptomatic carotid artery disease have a very low event rate per year – approximately 1% per year with a marginal absolute benefit when subjected to carotid endarterectomy Citation[3]. Higher-risk subsets, that is, those with symptomatic carotid artery disease, carry a much higher annual event rate (10–20% per year) when treated medically and have a larger absolute benefit from surgical treatment Citation[4,5]. The EVA-3S trial was actually terminated early owing to an increased event rate (stroke or death) in the stenting arm compared to the surgical arm of the trial (9.6 vs 3.6%, respectively). The SPACE trial was unable to prove noninferiority of carotid stenting versus carotid endarterectomy, with event rates of 6.84 versus 6.34%, respectively. Ongoing trials, such as Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) will help answer these questions Citation[6] but, to date, carotid artery stenting has not consistently shown superiority or even noninferiority compared with traditional carotid artery endarterectomy Citation[6].
Abdominal aortic aneurysms (AAAs) represent the 10th to 13th leading causes of death and can be prevented by appropriately timed surgical intervention Citation[7,8]. In an effort to minimize the physiological stress to the patient, while at the same time offering a ‘minimally invasive’ repair, aortic stent grafting has been developed. The Dutch Randomized Endovascular Aneurysm Management (DREAM) trial was designed to evaluate open versus endovascular repair of AAAs in a randomized fashion Citation[9]. Although there was a perioperative survival advantage to endovascular repair, by 2 years, the survival rate of the surgically treated and the endovascularly treated groups were statistically equivalent, 89.6 versus 89.7%, respectively. Surprisingly, in patients unfit for open surgical repair, the Endovascular Aneurysm Repair-2 (EVAR-2) trial failed to show a survival advantage in patients treated with an endograft versus those treated medically Citation[10].
Similarly, although more than 1 million coronary stents are implanted annually, this approach has failed to consistently show benefit over aggressive medical therapy (except in high-risk subgroups). In patients with stable coronary artery disease (CAD), the Effect of Percutaneous Coronary Intervention on Quality of Life in Patients with Stable Coronary Disease (COURAGE) trial, with all of its limitations, failed to show a survival advantage of percutaneous coronary intervention over aggressive medical therapy Citation[11]. Furthermore, by 3 years, any quality-of-life or symptom improvement of percutaneous coronary intervention over medical therapy was lost.
So why are so many of these procedures performed? Although many of the procedures in interventional cardiology have not shown a mortality advantage, these techniques offer the patient a less invasive treatment. Often, patients are treated and discharged the same day, whereas they would otherwise have required several days in the hospital for recovery. Furthermore, these techniques allow patients with severe comorbidities to undergo treatment without increasing the risk of periprocedural complications.
Two areas in interventional cardiology that are undergoing significant study to further enhance patient care are percutaneous valve repair or replacement and the treatment of patients with critical limb ischemia. Currently, patients with severe comorbidities are not candidates to have valvular heart surgery – there are now studies underway in which the aortic valve or the mitral valve can be repaired or replaced through a minimally invasive approach. This offers hope to patients who otherwise would be left to the natural history of their condition. Separately, patients with critical limb ischemia who are at risk for amputations are now being offered percutaneous treatment of their disease. Limb salvage rates now exceed 75% in these patients who otherwise would have lost a limb.
Interventional cardiology is an amazing field. Procedures are now being performed that were only dreamed of even a decade ago. Although the clinical results have not always demonstrated superiority to standard care, we are able to offer patients less invasive and less morbid therapies.
Financial & competing interests disclosure
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
No writing assistance was utilized in the production of this manuscript.
References
- Mas J-L, Chatellier G, Beyssen B et al. Endarterectomy versus stenting in patients with symptomatic severe carotid stenosis. N. Engl. J. Med.355, 1660–1671 (2006).
- SPACE Collaborative Group. 30 day results from the SPACE trial of Stent-Protected Angioplasty versus Carotid Endarterectomy in symptomatic patients: a randomised non-inferiority trial. Lancet368, 1239–1247 (2006).
- Executive Committee for the Asymptomatic Carotid Atherosclerosis Study. Endarterectomy for asymptomatic carotid artery stenosis. JAMA273, 1421–1428 (1995).
- North American Symptomatic Carotid Endartectomy Trial Collaborators. Benefecial effect of carotid endarterectomy in symptomatic patients with high grade carotid stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaboration. N. Engl. J. Med.325, 445–453 (1991).
- European Carotid Surgery Trialists Collaborative Group. Randomised trial of endarterectomy for recently symptomatic carotid stenosis: final results of the MRC European Carotid Surgery Trial (ECST). Lancet351, 1379–1387 (1998).
- Major ongoing stroke trials. Stroke37, e27–e35 (2006).
- Lederle FA, Johnson GR, Wilson SE et al. Rupture of large abdominal aortic aneurysms in patients refusing or unfit for elective repair. JAMA287, 2968–2972 (1998).
- Lederle FA, Wilson SE, Johnson GR et al. Immediate repair compared with surveillance of small abdominal aortic aneurysms. N. Engl. J. Med.346, 1437–1444 (2002).
- Blankensteijn JD, de Jong SECA, Prinssen M et al. Two year outcomes after conventional or endovascular repair of abdominal aortic aneurysms. N. Engl. J. Med.352, 2398–2405 (2005).
- EVAR Trial Participants. Endovascular aneurysm repair and outcome in patients unfit for open repair of abdominal aortic aneurysm (EVAR trial 2), randomised controlled trial. Lancet365, 2187–2192 (2002).
- Weintraub WS, Spertus JA, Kolm P, Maron DJ et al. Effect of PCI on quality of life in patients with stable coronary disease. N. Engl. J. Med.359, 677–687 (2008).