There are three management options for patients with ischaemic heart disease:

• Medical therapy and risk factor modification:
  This is the main option for stable, low-risk patients, and should be given to all patients with ischaemic heart disease (see separate articles Secondary Prevention of Ischaemic Heart Disease and Cardiac Rehabilitation). In low-risk patients with stable coronary artery disease, aggressive lipid-lowering therapy is at least as effective as angioplasty in reducing the incidence of ischaemic events.¹
  
  
• Coronary artery bypass graft (CABG) surgery:
  This has been shown to produce better survival rates compared with medical therapy. However the degree of improvement decreases after five years.²
  
  
• Percutaneous coronary intervention (PCI):
  This is for patients with single-vessel coronary artery disease; percutaneous transluminal coronary angioplasty (PTCA) offers earlier and more complete relief of angina than medical therapy and is associated with better performance on the exercise test. However, PTCA initially costs more than medical treatment and is associated with a higher frequency of complications.³
  
  In general, PTCA is less invasive and requires a shorter hospitalisation and recovery time than does bypass surgery. However, the disadvantages of PTCA include restenosis of treated lesions and a lesser ability to revascularise all lesions in patients with multivessel disease.⁴ Stents are more effective than PTCA in preventing adverse events and revascularisation.

There continues to be controversy and debate regarding the exact indications of CABG and PTCA with arguments in favour of the benefits of CABG⁵ and those who feel modern techniques for PTCA make this the method of choice for the majority of patients.⁶ One recent study found that among patients judged clinically appropriate for coronary revascularisation, CABG seemed cost-effective but PCI did not.⁷

Investigations

Risk assessment (and modification)

This includes smoking, weight, diet, exercise, cardiac function, blood pressure, glucose control, lipids and renal function.

Methods for recognising severe ongoing ischaemia

These include:

• A resting ECG with ST depression in multiple leads in someone who has recently had unstable angina.
• A strongly positive exercise ECG test, e.g. widespread ST depression in the first two stages of the Bruce Protocol (less than 6 minutes).
• Strongly positive myocardial perfusion scan, e.g. one large or multiple reversible perfusion defects.

Angiography

This is for patients with:

• Evidence of continuing extensive ischaemia (e.g. a strongly positive exercise test) and/or,
• Angina that persists despite optimal medical therapy and lifestyle advice.

Assessment of urgency/risk/priority

Using a published stratification system to help determine the balance of risks and benefits and to help determine each patient's relative priority for treatment.

• The Ontario scoring system: designed to assess the urgency of intervention.⁸ The three main urgency determinants are severity and stability of symptoms of angina, coronary anatomy from angiographic studies, and results of noninvasive tests for risk of ischaemia.
• The Parsonnet score and European System for Cardiac Operative Risk Evaluation (EuroSCORE): the Parsonnet score is a simple method (based on 14 risk factors) of risk stratification of open-heart surgery patients that makes it possible to analyse operative results by risk groups and to compare results in similar groups between institutions.⁹ The EuroSCORE is a similar European system for cardiac operative risk evaluation based on a large database.¹⁰

Special considerations

A number of important factors influence the likely balance of risks and benefits. These include:⁹

• Smoking:
  This is associated with poorer long-term survival after CABG. Those who stop smoking are less likely to undergo repeat surgery or to have a heart attack.
• Diabetes mellitus:
  Patients have poorer long-term survival after revascularisation. Good control of diabetes and hypertension reduces the rate of progression of vascular disease.
• Impaired left ventricular function:
  Despite a higher operative mortality, they also obtain greater long-term survival benefit from revascularisation than people without impaired left ventricular function.
• Advanced age:
  The procedure-associated risk rises rapidly with age.
• Gender:
  Women may have a higher procedure-associated mortality than men.¹¹
• Recent myocardial infarction or episode of unstable angina:
  Recent coronary events increase procedural risk.
• Unfavourable coronary anatomy:
  Extensive disease in the distal parts of coronary arteries reduces the likely benefits of intervention.

Coronary artery bypass surgery

Indications

• Angiogram has shown significant narrowing of:
  • Left main coronary artery
  • Three coronary arteries
  • Two coronary arteries including the proximal left anterior descending coronary artery or symptom relief (i.e. with suitable coronary anatomy where severe angina persists despite optimal medical therapy)
• Coronary artery bypass graft (CABG) continues to be the complete revascularisation option for patients with multivessel, multi-lesion coronary artery disease (CAD), in part because of its application to chronic occlusions.
• The long-term outcome for the use of CABG for patients with diabetes has been consistently superior to the use of percutaneous coronary intervention (PCI). The difference is reduced with the use of stents and adjunctive medication but CABG is still the preferred method of revascularisation for patients with diabetes.

Complications

Some of the morbidity following CABG relates to the use of cardiopulmonary bypass and so off-pump coronary artery bypass (OPCAB) surgery has been developed.¹⁰

• Neurological abnormalities include major focal neurological deficits, stupor, coma, and deterioration in intellectual function or memory.
• Mediastinitis.
• Renal dysfunction.
• Approximately 50% of vein grafts are closed by 10 years after operation.¹²

Percutaneous transluminal coronary angioplasty

Indications

• Operable narrowings of one vessel or two coronary arteries without significant narrowing of the left main stem.
  
  Although percutaneous transluminal coronary angioplasty (PTCA) was initially used only for the treatment of single-vessel coronary artery disease (CAD), in recent years new medicines (e.g. glycoprotein IIb/IIIa receptor blocking drugs) and new equipment (e.g. intracoronary stents) have been developed and have resulted in its expanded use for patients with multivessel disease.
  
  
• The National Institute for Health and Clinical Excellence (NICE) recommends that stents should be used routinely when percutaneous coronary intervention (PCI) is used for patients with either stable or unstable angina or with acute myocardial infarction.¹³ Drug-eluting stents are recommended for use if the target artery to be treated has less than a 3-mm calibre or the lesion is longer than 15 mm.¹⁴ The price difference between drug-eluting stents and bare-metal stents should also be no more than £300.
  
  The use of stents, aspirin, clopidogrel, and glycoprotein IIb/IIIa inhibitors lowers the rate of restenosis to less than 10% at 6 months in optimal circumstances.¹⁵ Recent studies of stents coated with antiproliferative agents such as sirolimus have shown promise in lowering the restenosis rate after stenting.¹⁶ Folic acid supplementation following stenting has also been shown to lower the restenosis rate.¹⁷
  
  It is also recommended that a glycoprotein IIb/IIIa inhibitor be considered as an adjunct to PCI for all patients with diabetes undergoing elective PCI, and for those patients undergoing complex procedures (e.g. multivessel PCI, insertion of multiple stents, vein graft PCI or PCI for bifurcation lesions).
  
  
• PCI is the acute stabilisation method of choice for patients with ongoing ischaemia and acute myocardial infarction, especially among patients with haemodynamic compromise, and/or major comorbidity.¹⁸
  
  In procedurally uncomplicated elective PCI, where the risk of adverse sequelae is low, use of a glycoprotein IIb/IIIa inhibitor is not recommended unless unexpected immediate complications occur.¹⁹
  
  
• Emergency PTCA is now used in some centres as first-line management for all patients following acute myocardial infarctions and, if not used as a first-line intervention, is recommended for those patients who are unsuitable for thrombolysis, or for those for whom thrombolysis has failed.⁶
  
  If PCI is indicated as part of the early management of unstable angina or non-ST elevation myocardial infarction, but is delayed, then the use of a glycoprotein IIb/IIIa inhibitor is recommended as an adjunct to PCI.

Complications

• The use of coronary stents has reduced the need for repeat revascularisation when compared with previous studies that used balloon angioplasty, though the rate remains significantly higher than in patients managed with CABG.²⁰
• As measured one year after the procedure, coronary stenting for multivessel disease is less expensive than bypass surgery and offers the same degree of protection against death, stroke, and myocardial infarction. However, stenting is associated with a greater need for repeated revascularisation.²¹

Document references

1. Pitt B, Waters D, Brown WV, et al; Aggressive lipid-lowering therapy compared with angioplasty in stable coronary artery disease. Atorvastatin versus Revascularization Treatment Investigators. N Engl J Med. 1999 Jul 8;341(2):70-6. [abstract]
2. Varnauskas E; Twelve-year follow-up of survival in the randomized European Coronary Surgery Study. N Engl J Med. 1988 Aug 11;319(6):332-7. [abstract]
3. Parisi AF, Folland ED, Hartigan P; A comparison of angioplasty with medical therapy in the treatment of single-vessel coronary artery disease. Veterans Affairs ACME Investigators. N Engl J Med. 1992 Jan 2;326(1):10-6. [abstract]
4. Bakhai A, Hill RA, Dundar Y, et al; Percutaneous transluminal coronary angioplasty with stents versus coronary artery bypass grafting for people with stable angina or acute coronary syndromes. Cochrane Database Syst Rev. 2005 Jan 25;(1):CD004588. [abstract]
5. Corr LA, Stables R; Managing heart disease: Coronary revascularization: knife or catheter? European Heart Journal; Supplements (2003) 5 (Supplement B), B43-B48.
6. European Society of Cardiology; Guidelines for Percutaneous Coronary Interventions. March 2005.
7. Griffin SC, Barber JA, Manca A, et al; Cost effectiveness of clinically appropriate decisions on alternative treatments for angina pectoris: prospective observational study. BMJ. 2007 Mar 24;334(7594):624. Epub 2007 Mar 5. [abstract]
8. Naylor CD, Baigrie RS, Goldman BS, et al; Assessment of priority for coronary revascularisation procedures. Lancet. 1990 May 5;335(8697):1070-3. [abstract]
9. Parsonnet V, Dean D, Bernstein AD; A method of uniform stratification of risk for evaluating the results of surgery in acquired adult heart disease. Circulation. 1989 Jun;79(6 Pt 2):I3-12. [abstract]
10. Nashef SA, Roques F, Michel P, et al; European system for cardiac operative risk evaluation (EuroSCORE). Eur J Cardiothorac Surg. 1999 Jul;16(1):9-13. [abstract]
11. Mikhail GW; Coronary revascularisation in women. Heart. 2006 May;92 Suppl 3:iii19-23. [abstract]
12. Eagle KA, Guyton RA, Davidoff R, et al; ACC/AHA 2004 guideline update for coronary artery bypass graft surgery: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1999 Guidelines for Coronary Artery Bypass Graft Surgery). Circulation. 2004 Oct 5;110(14):e340-437.
13. Ischaemic heart disease - coronary artery stents, NICE Technology Appraisal (2003)
14. Coronary artery disease - drug-eluting stents, NICE Technology Appraisal Guidance (July 2008)
15. No authors listed; Randomised placebo-controlled and balloon-angioplasty-controlled trial to assess safety of coronary stenting with use of platelet glycoprotein-IIb/IIIa blockade. Lancet. 1998 Jul 11;352(9122):87-92. [abstract]
16. Rensing BJ, Vos J, Smits PC, et al; Coronary restenosis elimination with a sirolimus eluting stent: first European human experience with 6-month angiographic and intravascular ultrasonic follow-up. Eur Heart J. 2001 Nov;22(22):2125-30. [abstract]
17. Schnyder G, Roffi M, Pin R, et al; Decreased rate of coronary restenosis after lowering of plasma homocysteine levels. N Engl J Med. 2001 Nov 29;345(22):1593-600. [abstract]
18. Morrison DA, Sacks J; Balancing benefit against risk in the choice of therapy for coronary artery disease. Lesson from prospective, randomized, clinical trials of percutaneous coronary intervention and coronary artery bypass graft surgery. Minerva Cardioangiol. 2003 Oct;51(5):585-97. [abstract]
19. Acute coronary syndromes - glycoprotein IIb/IIIa inhibitors, NICE Technology Appraisal (2002)
20. No authors listed; Coronary artery bypass surgery versus percutaneous coronary intervention with stent implantation in patients with multivessel coronary artery disease (the Stent or Surgery trial): a randomised controlled trial. Lancet. 2002 Sep 28;360(9338):965-70. [abstract]
21. Serruys PW, Unger F, Sousa JE, et al; Comparison of coronary-artery bypass surgery and stenting for the treatment of multivessel disease. N Engl J Med. 2001 Apr 12;344(15):1117-24. [abstract]

Internet and further reading

• Acute coronary syndromes, SIGN (2007)
• Secondary prevention in primary and secondary care for patients following a myocardial infarction, NICE Clinical Guideline (2007)
• Management of acute myocardial infarction in patients presenting with persistant ST-segment elevation, European Society of Cardiology (November 2008)
• Heart bypass: animation. This animation explains how a coronary artery bypass, a surgical procedure, is performed and why it would be needed. A short video from NHS Choices. (November 2008)

Acknowledgements