Multivessel coronary artery disease
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Associate Editors-In-Chief: Joanna J. Wykrzykowska, MD,[2]; Robert Sperling, MD; Brian Bigelow, MD; Roger J. Laham, MD [3]; Neil M. Gheewala, MD; Randall K. Harada, MD
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Background
Multi-vessel coronary artery disease (CAD) is associated with a higher burden of co-morbidities, LV dysfunction, and cardiovascular risk. Medical decisions are frequently based on clinical trial data that are now potentially supplanted by improvements in contemporary medical, percutaneous, and surgical strategies.
Goals of Treatment
Management of multi-vessel coronary artery disease focuses on:
- Reduction of adverse event risk
- Relief of angina and heart failure symptoms
- Delaying cardiac morbidity
Treatment Choices
- Medical therapy: Anti-anginal and anti-platelet medications as well as high dose statins; new anti-anginals
- Percutaneous coronary intervention (PCI) with drug eluting stents
- Coronary artery bypass graft surgery (CABG)
Advantages of Each Choice
Medical Therapy
All patients should receive optimal medical therapies to reduce cardiovascular event-risk and angina. Patients with lower-risk, stable CAD may be effectively treated by medical therapy. Medical therapy has no procedural risk or prolonged convalescence, but the COURAGE Trial[1] showed an increased risk of angina and a decreased quality of life. Moreover, 30% of the patients eventually needed revascularization. Approximately 2/3 of the study population in COURAGE had multi-vessel CAD, and randomization to an initial strategy of medical therapy resulted in similar rates of death and myocardial infarction (MI) to an initial strategy of PCI.
Revascularization
When compared with medical therapy, revascularization (PCI or CABG) is associated with less angina, fewer anti-anginal medications, and better functional capacity and quality of life.
Revascularization by CABG
CABG is associated with a lower incidence of recurrent angina and need for repeat revascularization. It reduces late cardiac mortality in diabetic patients who received at least 1 internal mammary (IMA) graft. The rate of revascularization may be comparable in the era of drug eluting stents (trials are pending).
Recommendations are limited by the quality of data. For instance, older trials of CABG vs. medical therapy had little use of IMA conduit and limited use of ASA, ACEIs, and statins. Many PCI vs. CABG trials did not have widespread use of stents (either bare metal or drug-eluting) or GP IIb/IIIa inhibitors, and <10% of patients screened for trials of PTCA vs. CABG were randomized, and therefore highly select. With multivessel stenting, TLR rates become cumulative TLR rate per lesion is triple that per patient. Diabetics with both retinopathy and nephropathy appear to have very high major adverse cardiac events (MACE) rates with PCI (up to 50%).
Several randomized trials of CABG versus medical therapy support the concept of greater absolute benefit of CABG in respect to long-term survival in patients with more extensive or proximal CAD or those with LV contractile dysfunction. These data were limited by low usage of IMA grafting, anti-platelet agents, and high cross-over of the medical treatment arm. Specifically, CABG offers survival benefit in patients with left main stenosis, multivessel disease and LV systolic dysfunction, 3-vessel disease with proximal LAD stenosis regardless of LV function, and 2-vessel disease and LV systolic dysfunction, especially with proximal disease and severe angina.
Revascularization by PCI
The subgroup analysis of patients with stable, multi-vessel CAD in the COURAGE trial suggested no difference in death and MI rates between PCI- and medically-treated groups.
PCI vs. CABG
In comparison to CABG, PCI is less invasive, has a shorter hospital stay and convalescence, is less expensive initial hospital stay; cost advantage may be lost over long-term due to need for repeat revascularization; one must be confident of their ability to achieve complete revascularization with PCI when offering it as an alternative to CABG.
The BARI trial showed similar 5-year survival among over 1800 patients randomized to an initial strategy of PTCA or CABG for multi-vessel CAD despite the higher rates of “complete revascularization” in the CABG arm. This trial preceded the use of drug eluting stents. However, these treatments differ in the need for repeat revascularizations and relief of angina.
Due to higher CABG mortality in patients with UA/NSTEMI, a strategy of PCI to the “culprit artery” followed by elective, as needed, revascularization of the residual disease may be employed. Identification of the culprit artery requires localizing ECG, echocardiographic, or angiographic features (coronary thrombus, ulcerative plaque, slow flow, a high grade stenosis, or pressure wire technique).
The ARTS and SYNTAX trials showed higher primary event rates in patients randomized to PCI versus CABG, driven by higher need for revascularization. Rates of hard events such as death and MI were similar between the treatment groups.
Patient selection and initial approach
- Risk factor modification for all patients (smoking cessation, treatment of HTN, correction of dyslipidemia)
- Choose medical therapy when LV systolic function normal or mildly depressed & lifestyle acceptable w/ medical therapy
- Choose revascularization:
1) when unacceptable syptoms persist despite optimal medical therapy
2) when lesions and risk factors are present for which revascularization improves morbidity & mortality compared w/ medical therapy
- Scenarios favoring CABG vs. medical therapy for prolonging survival:
- left main stenosis >50%,
- multivessel disease & LV systolic dysfunction,
- 3-vessel disease with proximal LAD stenosis regardless of LV function,
- 2-vessel disease & LV systolic dysfunction (especially with proximal disease & severe angina)
- Choose PCI over CABG:
- lesions suitable for PCI,
- younger patients with expected CABG in future to delay time to surgery,
- high operative risk (including: cerebrovascular disease & severe COPD), illness limiting survival,
- poor conduit (no IMA available or poor vein quality),
- patient prefers to avoid surgery
- Choose CABG over PCI:
- in the presence of associated valvular disease requiring surgical repair,
- complete functional revascularization unlikely to be achieved w/PCI,
- lesions not suitable for stenting (low likelihood of success, high risk of complications, high risk of restenosis),
- patient prefers to limit number of revascularization procedures
- CABG vs. PCI Outcomes:
- mortality & nonfatal MI rates not significantly different
- higher rate of recurrent angina & repeat revascularization after PCI (most trials in low-risk patients with 2-vessel disease & normal LV function); this may change in the near future with coated stents
- In nondiabetic patients with 3-vessel disease and poor LV systolic function, consider PCI in select patients with low-risk lesions if complete revascularization can be achieved; risk and benefits of lifelong plavix and risks of stent thrombosis must be discussed extensively
- Diabetic patients with 2- or 3-vessel disease:
- in general, CABG is recommended as BARI trial showed improved survival after CABG compared with multivessel PCI if at least one IMA conduit was used & there were 4 or more lesions, especially in patients with LV systolic dysfunction
- however, BARI trial was done in the pre-stent era and before the widespread use of GP IIb/IIIa inhibitors
- there was no difference in survival among DM patients treated with CABG vs. PCI in 2 nonrandomized trials incl 5-y survival in BARI registry
- it is possible that carefully selected patients with Diabetes can be successfully managed with PCI in the drug eluting stent era
Technical and pharmacologic considerations
- One may need to stage the procedure because of contrast load and radiation dose, as well as procedure time.
- Starting with the most challenging lesion in patients for whom CABG is an option, may be advisable to evaluate feasibility of complete revascularization
- Assessment of patient’s ability to comply with lifetime dual antiplatelet therapy is also crutial especially with bifurcation stenting, long lesions and small vessels, which are common in patients with multivessel disease where risk of stent thrombosis is highest
Expected long-term outcomes
- Resolution of angina and ischemia with both PCI and CABG and prolongation of life in selected high-risk patients with CABG
- Consider revascularization for persistent angina or ischemia with medical therapy
- Consider CABG when PCI does not successfully revascularize significant stenoses
- Consider PCI to treat unrevascularized lesions when angina or ischemia persist after CABG, or when grafts fail (15% in the first month and 80% in 10-15 years)