Chronic stable angina revascularization percutaneous coronary intervention

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [3] Phone:617-632-7753; Associate Editor(s)-In-Chief: Cafer Zorkun, M.D., Ph.D. [4]; John Fani Srour, M.D.; Jinhui Wu, M.D.; Lakshmi Gopalakrishnan, M.B.B.S.

Overview

Percutaneous coronary intervention for coronary artery disease first began in 1977, as a valuable mode of revascularization, wherein at the point of coronary stenosis a catheter-borne balloon is inflated to relieve the stenosis. The advantages of PCI for the treatment of CAD are many and include a low level of procedure-related morbidity and mortality rate in properly selected patients, a shorter hospital stay, early return to activity, and the feasibility of multiple procedures. The risk of acute coronary occlusion during PCI and increased incidence of restenosis in lesions that were successfully treated limits the use of PCI.

Ideal candidates for PTCA/PCI include patients with stable angina less than 75 years of age, with single-vessel and/or single-lesion CAD, without a history of diabetes. Objective large ischemia, in particular, lesions less than 10 mm, readily accessible, concentric, and discrete are best suited for revascularization by PCI. On the contrary, chronic total occlusions that cannot be crossed, lesions greater than 20 mm, tortuous, irregular, angulated, calcified, severely stenotic with one or more lesion greater than 90% stenosis present in an artery are associated with an increased risk of morbidity and mortality from the procedure. In addition, PCI is used with reservation in diabetics with multi-vessel disease and in patients with unprotected left main stenosis. Other important factors include the operator volume and the presence or absence of onsite cardiovascular surgeon.

Primary success of coronary intervention is generally defined as an absolute increase of 20% points in the luminal diameter and a final diameter obstruction of less than 30%. Such angiographic success can be anticipated in more than 90% of properly selected patients.

Over the years, alternative methods of percutaneous treatment developed include the use of intracoronary brachytherapy for in-stent restenosis, cutting balloon with metal razors to avoid the spillage and subsequent reduction in the incidence of vessel trauma, burr rotablation that pulverizes the atheromatous material and intracoronary stents designed to maintain the lumen size.

Indications

• PCI has been shown to reduce the frequency of anginal symptoms and improve exercise tolerance in patients with single and double-vessel disease.

• In the ACME trial, approximately 213 patients with stable single-vessel CAD were assessed to compare the effects of PCI with medical therapy on angina and exercise tolerance. The study demonstrated that PCI offered earlier and more complete relief of angina than medical therapy (64% patients in PCI group versus 46% medically treated group; p=less than 0.01) and was associated with a better exercise tolerance (2.1 in the PCI group versus 0.5 minutes in the medically treated group; p=less than 0.0001) as observed at 6-month follow-up.

• In a sub-study that assessed the long-term effectiveness of PCI for single-vessel CAD, demonstrated sustained benefits with PCI similar to the ACME trial, hence making it an attractive therapeutic option.

• In patients with objective large ischemia associated with severe angina, PCI has shown to significantly reduce mortality and provide greater symptomatic improvement. However, on the contrary, patients with mild symptoms do not benefit from PCI.

• In the ACIP study, that compared the 12-week efficacy of the three treatment strategies such as medical therapy, medical therapy plus ambulatory ECG monitoring or revascularization to suppress cardiac ischemia, and to assess the feasibility of a prognosis trial in patients with asymptomatic cardiac ischemia, demonstrated both stress-inducible ischemia and two or more ischemic episodes on holter monitoring. Two years after randomization, the total mortality was significantly reduced from 6.6% in the angina-guided strategy to 4.4% in the ischemia-guided strategy and 1.1% in the revascularization strategy (p=less than 0.02). The rate of composite primary end-points was also significantly reduced from 41.8% in the angina-guided strategy to 38.5% in the ischemia-guided strategy and 23.1% in the revascularization strategy (p=less than 0.001).

• The RITA-2 trial compared the long-term effects of PCI and conventional medical therapy in patients with CAD, demonstrated an early intervention with PCI was associated with greater symptomatic improvement, particularly observed in patients with more severe angina. However, on the contrary, the primary composite end-points during a median 2.7 year follow-up was significantly higher in patients treated with PCI than in patients treated with medical therapy (6.3% in the PCI group versus 3.3% in the medically treated group; p=0.02).

• A meta-analysis of six randomized controlled trials that assessed the benefit of PCI versus medical treatment for patients with non-acute coronary heart disease, reported that PCI may lead to a greater reduction in angina in patients with CAD in comparison to medical therapy; however, sufficient patients were not included to assess the effect of PCI on MI, death, or subsequent revascularization.

• In the TIME study, that assessed the long-term survival and quality of life in elderly patients with CCS class II or greater angina receiving atleast two anti-anginal medication at baseline, demonstrated similar long-term survival benefits observed in both the groups; however, freedom from major cardiovascular events remained higher in invasive therapy group versus the medical therapy group (39% versus 20%, p=less than 0.0001). Irrespective of whether patients were catheterized initially or only after failure to respond to medical therapy, their survival rates were better if they were revascularized within the first year.

• The AVERT trial, demonstrated that in patients with low-risk for coronary artery disease, an initial aggressive lipid-lowering therapy aimed at reversing plaque growth and promoting plaque stabilization, had significantly prolonged the time to first ischemic event (p=0.03) when compared to PCI and standard medical therapy. Hence, in low-risk patients with stable CAD, it is beneficial to start with medical therapy and reserve revascularization strategies for non-responders.

• Despite the high rates of restenosis associated with PCI, it may be beneficial for chronic total occlusions only in cases where the distal lumen could be accessed and favorable results could be obtained with stent implantation.

• The GISSOC trial, studied the benefit of stent implantation over balloon PTCA for the treatment of chronic total coronary occlusions. The study demonstrated a significant reduction in the major adverse cardiovascular events observed in the stent group during a 6-year follow-up (76.1% in the stent group versus 60.4% in the PTCA group; p=0.055) and attributed this reduction secondary to the target lesion revascularization free-survival rate (85.1% in the stent group versus 65.5% in the PTCA group; p=0.0165). However, in most cases, restenosis of the study occlusion was evident at nine-month angiography. Thus, the study concluded stent implantation was superior to balloon PTCA in chronic total occlusions that can be recanalized percutaneously and is a valuable long-term therapeutic option; however, at nine-month follow-up both the stent and PTCA results appear to remain stable.

• Similar benefits with stent implantation for chronic total occlusion were reported in few other studies such as:

• The PRISON study, that demonstrated a statistically significant reduction in the need for target lesion revascularization (29% in the PTCA group versus 13% in the stent group; p=less than 0.0001) and a non-significant rate of restenosis was observed (33% in the PTCA group versus 22% in the stent group; p=0.137).

• The SARECCO trial, demonstrated a significant event free survival in the stent group observed during a 2-year follow-up (26% in the group that received angioplasty alone versus 52% in the stent group; p=less than 0.05).

• The SICCO trial, reported a significant reduction in the target lesion revascularization (22% in the stent group versus 42% in the PTCA group; p=0.025) and restenosis (32% patients with stent and 74% patients with PTCA only; p=0.025) noted in the stent implantation group.

• The SPACTO trial, demonstrated significant reduction in the rates of restenosis (29% in the stent group versus 72% in the PTCA group; p=less than 0.01) and reocclusion (3% in the stent group versus 24% in the PTCA group) observed in the stent group. At follow-up,there was also a significant reduction in cardiac events (p=less than 0.03) and marked improvement in the anginal class (p=less than 0.01) reported in the stent group.

• The STOP study, demonstrated significant reduction in the rate of restenosis (42.1% in the stent group versus 70.9% in the PTCA group; p=0.034) and reocclusion (7.9% in the stent group versus 16.1% in the PTCA group) observed with the stent implantation. However, stent group was associated with more a diffuse in-stent restenosis in comparison to a focal re-stenosis in the PTCA group that occurred at the point of total obstruction (within 5mm).

• In patients with refractory ischemia and severe LV dysfunction with ejection fraction less than 35% may benefit from PCI in comparison to CABG.

• In patients with unprotected left main disease associated with high peri-operative risk for CABG, PCI with stent implantation may be considered as an revascularization option.

Complications of percutaneous coronary intervention

The improvements in devices, the use of stents, and aggressive antiplatelet therapy have significantly reduced the incidence of major procedural complications of PCI over the past 2 decades despite the increasing complexity of cases. However, as with any invasive procedure, complications can occur. The major complications of PTCA/PCI include coronary artery dissection and acute closure, intramural hematoma, coronary artery perforation, and occlusion of branch vessels: Dissections are found in up to 50 percent of patients immediately after PTCA. Intimal tears or dissections following PTCA have been arbitrarily divided into types A to F.

• Type A — Luminal haziness

• Type B — Linear dissection

• Type C — Extraluminal contrast staining

• Type D — Spiral dissection

• Type E — Dissection with reduced flow

• Type F — Dissection with total occlusion

These problems are now much less frequent since stent placement is performed in most percutaneous coronary procedures. Abrupt closure is most often due to arterial dissection and is manifested as acute ischemic chest pain and ECG changes. The incidence of abrupt closure with conventional balloon angioplasty (PTCA) is approximately 5% and is associated with a 10-fold increase in mortality to about 1 percent and nonfatal MI. The frequency of this complication, however, has now been greatly reduced by pretreatment with the platelet glycoprotein IIb/IIIa receptor blockers and by the insertion of an intracoronary stent. If stenting does not restore adequate flow, emergency CABG can be performed.

Coronary artery intramural hematoma is defined as an accumulation of blood within the medial space displacing the internal elastic membrane inward and the external elastic membrane outward, with or without identifiable entry and exit points. It is identified in 6.7 percent of procedures by intravascular ultrasound (IVUS).

Coronary artery perforation in the stent era is a rare but potentially disastrous complication.

Downstream embolization of thrombus or plaque contents with microvascular obstruction is common after PCI and occlusion of side branches has been reported in up to 19 percent of cases in which a stent was placed across a major side branch.

Stent thrombosis is catastrophic complication that usually leads to death or ST segment elevation MI. It is therefore a medical emergency. Stent thrombosis can occur acutely (during or soon after the PCI), subacutely (within 30 days after stent placement), or as a complication. Late stent thrombosis is associated with the cessation of aspirin or clopidogrel therapy. On the other hand, very late stent thrombosis, occurring after one year, is associated with drug-eluting stents.

Restenosis is the result of arterial damage with subsequent neointimal tissue proliferation. It is usually defined as a greater than 50% diameter stenosis. The incidence of angiographic restenosis is approximately 30% to 40% after PTCA. Intracoronary stents reduce the rate of angiographic and clinical restenosis and post-procedural myocardial infarction compared to percutaneous transluminal coronary angioplasty (PTCA) alone. Trials have demonstrated that the sirolimus and paclitaxel drug-eluting stents markedly reduced the incidence of in-stent restenosis and the rate of target lesion revascularization compared to bare metal stents. As a result, stents are currently utilized in nearly all percutaneous coronary interventions. However, the benefits of drug-eluting stents on restenosis must be weighed against rates of stent thrombosis, which often leads to death or MI, if dual antiplatelet therapy is prematurely discontinued. Restenosis occurs more frequently in diabetics, smaller arteries, among total occlusions, and in left anterior descending arteries, particularly proximal lesions. Since not all angiographic restenosis results in recurrent symptoms, the rates of clinical restenosis are lower than these angiographic estimates. Recurrent sever angina occurs in approximately half of the patients who develop angiographic restenosis and usually responds to stenting. In symptomatic patients with BMS restenosis, a repeat stenting using a DES is usually recommended. In symptomatic patients with intracoronary DES restenosis, there are insufficient data to suggest any specific treatment.

Clinical trial data: PTCA/PCI versus medical treatment in the management of stable angina pectoris

There are important limitations concerning the applicability of the results of older trials and even newer trials to the current clinical practice.

In early trials of percutaneous intervention versus medical therapy, the majority of patients underwent coronary angioplasty alone without stenting. For example, the benefits of PTCA have been compared to medical therapy in single vessel disease in the randomized Veterans Affairs Angioplasty Compared to Medicine (ACME) trial. PTCA resulted in a reduction in anginal symptoms compared to medical therapy (50% angina free versus 24% at one month), however, while the benefit of PTCA was still significant at 6 months, the magnitude of this benefit was reduced (64% angina free versus 45%). Patients treated with PTCA also had an improvement of 2.1  3.1 minutes in exercise duration which was significantly greater than the 0.5  2.2 minutes experienced in the medical therapy group.

Other older trials compared PTCA to both limited (AVERT trial) and optimal medical interventions (RITA-2 and MASS II). The findings of these trials were that patients undergoing PTCA had similar rates of death and myocardial infarction as those on medical therapy and were less likely to have angina during the first few years.

More recent literature provides comparison between the use of stents and medical management, however, there is few data examining the extensive use of drug eluting stents and current extensive antithrombotic regimens (clopidogrel and GP IIb/IIIa inhibitors). In the most recent trial, COURAGE, drug-eluting stents were used in only 15 percent of patients. However, the COURAGE trial has the data most applicable to current practice. In this study 2287 patients were randomized to either aggressive medical therapy alone or aggressive medical therapy plus PCI with bare metal stenting. Patients were required to have both objective evidence of ischemia and significant CHD in a least one vessel; 87 percent were symptomatic and 58 percent had Canadian Cardiovascular Society CCS class II or III angina. Patients were excluded if they had CCS class IV angina, ≥50 percent left main disease, a markedly positive treadmill test (significant ST segment depressions and/or a hypotensive response during stage I of the Bruce protocol), an LVEF less than 30 percent, or coronary lesions deemed unsuitable for PCI. All patients received optimal medical therapy with beta blockers, calcium channel blockers, nitrates, antiplatelet therapy (either aspirin or clopidogrel), and aggressive lipid-lowering therapy with statin (attained median LDL-cholesterol was 72 mg/dL at five years). Exercise was recommended to achieve further improvements in the lipid profile when necessary. The results were published at a median follow-up of 4.6 years. There was no significant difference between the two treatment strategies for the primary end point of death from any cause and non-fatal MI. There was no significant difference in the rates of hospitalization for ACS. Patients in the PCI group underwent significantly fewer subsequent revascularization procedures (21 versus 33 percent, HR 0.60, 95% CI 0.51-71).

The issue of whether patients who receive PCI plus optimal medical therapy have a better quality of life and less angina than those who receive optimal medical therapy was addressed in COURAGE as well:

At baseline, 22 percent of patients were free of angina. At three months, significantly more patients who received PCI were angina free (53 versus 42 percent), but at 36 months there was no significant difference (59 versus 56 percent). Patients in both groups showed significant improvements from baseline values in various measures of quality of life. The percent of patients with clinically significant improvement in parameters such as physical limitation, angina stability, angina frequency, and overall quality of life was significantly higher in the PCI group by the sixth months. However, there was no significant difference in these rates at 36 months.

The results of COURAGE demonstrate that PCI with bare metal stents plus optimal medical therapy and initial, optimal medical therapy with revascularization as necessary are comparable strategies.

ACC/AHA Guidelines- Revascularization With PTCA (or Other Catheter-Based Techniques) and CABG (DO NOT EDIT)

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Class I 1. PTCA for patients with two- or three-vessel disease with significant proximal left anterior descending CAD, who have anatomy suitable for catheter-based therapy, normal LV function, and who do not have treated diabetes. (Level of Evidence: B) 2. PTCA or CABG for patients with one- or two-vessel CAD without significant proximal left anterior descending CAD but with a large area of viable myocardium and high-risk criteria on noninvasive testing. (Level of Evidence: B) 3. In patients with prior PTCA, CABG or PTCA for recurrent stenosis associated with a large area of viable myocardium and/or high-risk criteria on noninvasive testing. (Level of Evidence: C) 4. PTCA or CABG for patients who have not been successfully treated by medical therapy and can undergo revascularization with acceptable risk. (Level of Evidence: B) Class IIa 1. Repeat CABG for patients with multiple saphenous vein graft stenoses, especially when there is significant stenosis of a graft supplying the left anterior descending coronary artery. PTCA may be appropriate for focal saphenous vein graft lesions or multiple stenoses in poor candidates for re-operative surgery. (Level of Evidence: C) 2. PTCA or CABG for patients with one- or two-vessel CAD without significant proximal left anterior descending CAD but with a moderate area of viable myocardium and demonstrable ischemia on noninvasive testing. (Level of Evidence: B) 3. PTCA or CABG for patients with one-vessel disease with significant proximal left anterior descending0 CAD. (Level of Evidence: B) Class IIb 1. Compared with CABG, PTCA for patients with two- or three-vessel disease with significant proximal left anterior descending CAD who have anatomy suitable for catheter-based therapy and who have treated diabetes or abnormal LV function. (Level of Evidence: B) 2. PTCA for patients with significant left main coronary disease who are not candidates for CABG. (Level of Evidence: C) 3. PTCA for patients with one- or two-vessel CAD without significant proximal left anterior descending CAD who have survived sudden cardiac death or sustained ventricular tachycardia. (Level of Evidence: C) Class III 1. PTCA or CABG for patients with one- or two-vessel CAD without significant proximal left anterior descending CAD who have mild symptoms that are unlikely due to myocardial ischemia or have not received an adequate trial of medical therapy and a. Have only a small area of viable myocardium or b. Have no demonstrable ischemia on noninvasive testing. (Level of Evidence: C) 2. PTCA or CABG for patients with borderline coronary stenoses (50% to 60% diameter in locations other than the left main) and no demonstrable ischemia on noninvasive testing. (Level of Evidence: C) 3. PTCA or CABG for patients with insignificant coronary stenosis (less than 50% diameter). (Level of Evidence: C) 4. PTCA in patients with significant left main CAD who are candidates for CABG. (Level of Evidence: B)

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ESC Guidelines- Revascularization to improve prognosis (DO NOT EDIT)

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Class IIa 1. PCI or CABG for patients with reversible ischaemia on functional testing and evidence of frequent episodes of ischaemia during daily activities. (Level of Evidence: C)

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ESC Guidelines- Revascularization to improve symptoms (DO NOT EDIT)

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Class I 1. PCI for one-vessel disease technically suitable for percutaneous revascularization in patients with moderate-to-severe symptoms not controlled by medical therapy, in whom procedural risks do not outweigh potential benefits. (Level of Evidence: A) 2. PCI for multi-vessel disease without high-risk coronary anatomy, technically suitable for percutaneous revascularization in patients with moderate-to-severe symptoms not controlled by medical therapy, in whom procedural risks do not outweigh potential benefits. (Level of Evidence: A) Class IIa 1. PCI for one-vessel disease technically suitable for percutaneous revascularization in patients with mild-to-moderate symptoms which are nonetheless unacceptable to the patient, in whom procedural risks do not outweigh potential benefits. (Level of Evidence: A) 2. PCI for multi-vessel disease technically suitable for percutaneous revascularization in patients with mild-to-moderate symptoms which are nonetheless unacceptable to the patient, in whom procedural risks do not outweigh potential benefits. (Level of Evidence: A)

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Vote on and Suggest Revisions to the Current Guidelines

• The Chronic Stable Angina Living Guidelines: Vote on current recommendations and suggest revisions to the guidelines

Sources

• The ACC/AHA/ACP–ASIM Guidelines for the Management of Patients With Chronic Stable Angina

• Guidelines on the management of stable angina pectoris: The Task Force on the Management of Stable Angina Pectoris of the European Society of Cardiology

• TheACC/AHA 2002 Guideline Update for the Management of Patients With Chronic Stable Angina

• The 2007 Chronic Angina Focused Update of the ACC/AHA 2002 Guidelines for the Management of Patients With Chronic Stable Angina

References

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