Patients should be informed as to the nature of their condition and reassured that the prognosis is good (annual mortality less than two per cent). Underlying problems, such as anaemia or hyperthyroidism, should be treated. Management of coexistent conditions, such as diabetes and hypertension, should be optimized. Risk factors should be evaluated and steps made to correct them where possible; for example, smoking must be stopped, hypercholesterolaemia should be identified and treated, weight loss where appropriate and regular exercise should be encouraged.
Choosing between medical therapy and revascularization (coronary artery bypass grafting and angioplasty) can be difficult and will depend on a number of factors including symptoms,angiographic anatomy and patient/physician preference. The various treatment options are not mutually exclusive and should be considered as complementary.
Medical Treatment
Progonostic Therapies
1) Aspirin reduces the risk of coronary events in patients with coronary artery disease. All patients with angina, therefore, should take aspirin (75 mg daily is probably adequate) unless contraindicated.
2) Lipid-lowering therapy should be used in patients with total cholesterol above 4.8 mmol/l(190 mg per cent) (particularly if the LDL is > 3.3 mmol/l (> 130 mg per cent) and the HDL is < 1.0 mmol/l (<40 mg per cent)), despite a low fat diet.
Symptomatic Treatment
1) Glyceryl trinitrate (GTN) used sublingually, either as a tablet or as a spray, gives prompt relief (in a few minutes) and can also be used prior to performing activities that the patient knows will provoke angina.
2) Beta-blockers reduce the heart rate (negative chronotropic effect) and the force of ventricular contraction (negative inotropic effect), both of which reduce myocardial oxygen demand, especially on exertion. They are the drugs of choice in patients with previous myocardial infarction because of their proven benefit in secondary prevention. Atenolol, 50-100 mg once/twice daily or Metoprolol 25-100 mg twice daily, is often used. Carvedilol is preferred in case of heart failure and LV dysfunction. Dose: 6.25 mg twice daily to 25 mg twice daily. (See under heart failure).3) Long-acting nitrates (e.g. isosorbide mononitrate) are particularly useful in patients who gain relief from sublingual Glyceryl trinitrate(GTN). They reduce venous return and hence intracardiac diastolic pressures, reduce the impedance to the emptying of the left ventricle and relax the tone of the coronary arteries. Once-daily preparations are available which have a smooth pharmacokinetic profile and avoid the problem of tolerance.
4) Calcium-channel blockers block calcium flux into the cell, relax coronary arteries, cause peripheral vasodilation and reduce the force of left ventricular contraction, thereby reducing the oxygen demand of the myocardium. The non-dihydropyridine calcium antagonists (e.g.diltiazem and verapamil) also reduce the heart rate and are particularly useful anti-anginal agents, but should be used with caution in combination with beta-blockers. Short-acting dihydropyridines (e.g. nifedipine) can cause reflex tachycardia when used alone and are avoided. Slow-release formulations and the third-generation agents (e.g. amlodipine) can be used once daily and have a smooth profile of action with no significant effect on the heart rate and no significant negative inotropic effect.
5) Nicorandil is a potassium-channel activator with a nitrate component; it has both arterial and venous vasodilating properties. Whilst not used as a first-line drug, it is used when there are contraindications to the above agents and in refractory unstable angina.
6) Other metabolic agents are aimed at facilitating metabolic efficancy of the heart by partially inhibiting fatty acid oxidation and reduce the frequency of angina. These metabolic agents do not produce any significant haemodynamic effects. Drugs belonging to the above class are Trimetazidine and Ranazoline.
Coronary Revascularization
While the basic management of patients with CAD is medical, as described above, many patients are improved by coronary revascularization procedures. These interventions should be employed in conjunction with but do not replace the continuing need to modify risk factors and medical therapy.
Percutaneous Coronary Intervention (PCI)
PCI, most commonly percutaneous transluminal coronary angioplasty with stenting, is widely used to achieve revascularization of the myocardium in patients with symptomatic IHD and suitable stenoses of epicardial coronary arteries.A number of different mechanisms have been postulated, including fracturing and compression of the plaque, and stretching of the artery. Endothelial denudation, local dissection and distal embolization also occur and may account for some of the complications of the procedure.Ongoing studies of drug coated stents and optimal antithrombotic therapies are being carried out.
Risks
When coronary stenoses are discrete and symmetric, two and even three vessels can be dilated in sequence. However, case selection is essential in order to avoid a prohibitive risk of complications, which are usually due to dissection or thrombosis with vessel occlusion,uncontrolled ischaemia, and ventricular failure. Oral aspirin, clopidogrel, and intravenous heparin are given to reduce coronary thrombus formation. In unstable angina and when intracoronary thrombus is seen, the use of specific platelet glycoprotein receptor (GpIIb/IIIa) antagonists further reduces thrombotic complications and increases success. In experienced hands, the overall mortality rate is < 0.5 per cent, the need for emergency coronary surgery < 1 per cent, and the occurrence of clinical myocardial infarction < 2 per cent. Minor complications occur in 5 to 10 per cent of patients and include occlusion of a branch of a coronary artery.
Efficacy
Primary success, i.e., adequate dilation (an increase in luminal diameter > 20 per cent to a residual diameter obstruction < 50 per cent) with relief of angina, is achieved in > 95 per cent of cases. Recurrent stenosis of the dilated vessels occurs in ~20 per cent of cases within 6 months in 10 per cent of cases. Restenosis is more common in patients with diabetes mellitus, arteries with
small caliber, incomplete dilation of the stenosis, occluded vessels, obstructed vein grafts, dilation of the left anterior descending coronary artery, and stenoses containing thrombi. In diseased vein grafts procedural success has been improved by the use of capture devices or filters that prevent embolization, ischaemia, and infraction. Moreover, the use of stents that locally deliver antiproliferative drugs such as rapamycin can significantly reduce restenosis within the stent and 3 to 7 per cent at the edges. These significant advances are extending the use of PCI.Successful PCI produces effective relief of angina in > 95 per cent of cases and has been shown to be more effective than medical therapy for up to 2 years. More than one-half of patients with symptomatic IHD who require revascularisation can be treated initially by PCI. PCI is less invasive and expensive than CABG, usually requires only 1 to 2 days in the hospital, and permits considerable savings in the initial cost of care (however drug eluting stents currently available are expensive).
Coronary Artery Bypass Grafting (CABG)
Anastomosis of one or both of the internal mammary arteries or a radial artery to the coronary artery distal to the obstructive lesion is carried out. For additional obstructions that cannot be bypassed by an artery, a section of a vein (usually the saphenous) is used to form a connection between the aorta and the coronary artery distal to the obstructive lesion.The operation is relatively safe, with mortality rates < 1 per cent in patients without serious comorbid disease and normal left ventricular function, and when the procedure is performed by an experienced surgical team.
Intraoperative and postoperative mortality increase with the severity of ventricular dysfunction,comorbidities, age > 80 years, and lack of surgical experience. The effectiveness and risk of CABG vary widely depending on case selection and the skill and experience of the surgical team.Occlusion of venous grafts is observed in 10 to 20 per cent of patients during the first post operative year in approximately 2 per cent per year during 5 to 7 year follow-up and 4 per cent per year thereafter. Long-term patency rates are considerably higher for internal mammary and radial artery implantations than saphenous vein grafts. In patients with left anterior descending coronary artery obstruction, survival is better when coronary bypass involves the internal mammary artery rather than saphenous vein. Graft patency and outcomes are improved by meticulous treatment of risk factors, particularly dyslipidemia. Angina is abolished or greatly reduced in ~90 per cent of patients following complete revascularization.
Choosing between medical therapy and revascularization (coronary artery bypass grafting and angioplasty) can be difficult and will depend on a number of factors including symptoms,angiographic anatomy and patient/physician preference. The various treatment options are not mutually exclusive and should be considered as complementary.
Medical Treatment
Progonostic Therapies
1) Aspirin reduces the risk of coronary events in patients with coronary artery disease. All patients with angina, therefore, should take aspirin (75 mg daily is probably adequate) unless contraindicated.
2) Lipid-lowering therapy should be used in patients with total cholesterol above 4.8 mmol/l(190 mg per cent) (particularly if the LDL is > 3.3 mmol/l (> 130 mg per cent) and the HDL is < 1.0 mmol/l (<40 mg per cent)), despite a low fat diet.
Symptomatic Treatment
1) Glyceryl trinitrate (GTN) used sublingually, either as a tablet or as a spray, gives prompt relief (in a few minutes) and can also be used prior to performing activities that the patient knows will provoke angina.
2) Beta-blockers reduce the heart rate (negative chronotropic effect) and the force of ventricular contraction (negative inotropic effect), both of which reduce myocardial oxygen demand, especially on exertion. They are the drugs of choice in patients with previous myocardial infarction because of their proven benefit in secondary prevention. Atenolol, 50-100 mg once/twice daily or Metoprolol 25-100 mg twice daily, is often used. Carvedilol is preferred in case of heart failure and LV dysfunction. Dose: 6.25 mg twice daily to 25 mg twice daily. (See under heart failure).3) Long-acting nitrates (e.g. isosorbide mononitrate) are particularly useful in patients who gain relief from sublingual Glyceryl trinitrate(GTN). They reduce venous return and hence intracardiac diastolic pressures, reduce the impedance to the emptying of the left ventricle and relax the tone of the coronary arteries. Once-daily preparations are available which have a smooth pharmacokinetic profile and avoid the problem of tolerance.
4) Calcium-channel blockers block calcium flux into the cell, relax coronary arteries, cause peripheral vasodilation and reduce the force of left ventricular contraction, thereby reducing the oxygen demand of the myocardium. The non-dihydropyridine calcium antagonists (e.g.diltiazem and verapamil) also reduce the heart rate and are particularly useful anti-anginal agents, but should be used with caution in combination with beta-blockers. Short-acting dihydropyridines (e.g. nifedipine) can cause reflex tachycardia when used alone and are avoided. Slow-release formulations and the third-generation agents (e.g. amlodipine) can be used once daily and have a smooth profile of action with no significant effect on the heart rate and no significant negative inotropic effect.
5) Nicorandil is a potassium-channel activator with a nitrate component; it has both arterial and venous vasodilating properties. Whilst not used as a first-line drug, it is used when there are contraindications to the above agents and in refractory unstable angina.
6) Other metabolic agents are aimed at facilitating metabolic efficancy of the heart by partially inhibiting fatty acid oxidation and reduce the frequency of angina. These metabolic agents do not produce any significant haemodynamic effects. Drugs belonging to the above class are Trimetazidine and Ranazoline.
Coronary Revascularization
While the basic management of patients with CAD is medical, as described above, many patients are improved by coronary revascularization procedures. These interventions should be employed in conjunction with but do not replace the continuing need to modify risk factors and medical therapy.
Percutaneous Coronary Intervention (PCI)
PCI, most commonly percutaneous transluminal coronary angioplasty with stenting, is widely used to achieve revascularization of the myocardium in patients with symptomatic IHD and suitable stenoses of epicardial coronary arteries.A number of different mechanisms have been postulated, including fracturing and compression of the plaque, and stretching of the artery. Endothelial denudation, local dissection and distal embolization also occur and may account for some of the complications of the procedure.Ongoing studies of drug coated stents and optimal antithrombotic therapies are being carried out.
Risks
When coronary stenoses are discrete and symmetric, two and even three vessels can be dilated in sequence. However, case selection is essential in order to avoid a prohibitive risk of complications, which are usually due to dissection or thrombosis with vessel occlusion,uncontrolled ischaemia, and ventricular failure. Oral aspirin, clopidogrel, and intravenous heparin are given to reduce coronary thrombus formation. In unstable angina and when intracoronary thrombus is seen, the use of specific platelet glycoprotein receptor (GpIIb/IIIa) antagonists further reduces thrombotic complications and increases success. In experienced hands, the overall mortality rate is < 0.5 per cent, the need for emergency coronary surgery < 1 per cent, and the occurrence of clinical myocardial infarction < 2 per cent. Minor complications occur in 5 to 10 per cent of patients and include occlusion of a branch of a coronary artery.
Efficacy
Primary success, i.e., adequate dilation (an increase in luminal diameter > 20 per cent to a residual diameter obstruction < 50 per cent) with relief of angina, is achieved in > 95 per cent of cases. Recurrent stenosis of the dilated vessels occurs in ~20 per cent of cases within 6 months in 10 per cent of cases. Restenosis is more common in patients with diabetes mellitus, arteries with
small caliber, incomplete dilation of the stenosis, occluded vessels, obstructed vein grafts, dilation of the left anterior descending coronary artery, and stenoses containing thrombi. In diseased vein grafts procedural success has been improved by the use of capture devices or filters that prevent embolization, ischaemia, and infraction. Moreover, the use of stents that locally deliver antiproliferative drugs such as rapamycin can significantly reduce restenosis within the stent and 3 to 7 per cent at the edges. These significant advances are extending the use of PCI.Successful PCI produces effective relief of angina in > 95 per cent of cases and has been shown to be more effective than medical therapy for up to 2 years. More than one-half of patients with symptomatic IHD who require revascularisation can be treated initially by PCI. PCI is less invasive and expensive than CABG, usually requires only 1 to 2 days in the hospital, and permits considerable savings in the initial cost of care (however drug eluting stents currently available are expensive).
Coronary Artery Bypass Grafting (CABG)
Anastomosis of one or both of the internal mammary arteries or a radial artery to the coronary artery distal to the obstructive lesion is carried out. For additional obstructions that cannot be bypassed by an artery, a section of a vein (usually the saphenous) is used to form a connection between the aorta and the coronary artery distal to the obstructive lesion.The operation is relatively safe, with mortality rates < 1 per cent in patients without serious comorbid disease and normal left ventricular function, and when the procedure is performed by an experienced surgical team.
Intraoperative and postoperative mortality increase with the severity of ventricular dysfunction,comorbidities, age > 80 years, and lack of surgical experience. The effectiveness and risk of CABG vary widely depending on case selection and the skill and experience of the surgical team.Occlusion of venous grafts is observed in 10 to 20 per cent of patients during the first post operative year in approximately 2 per cent per year during 5 to 7 year follow-up and 4 per cent per year thereafter. Long-term patency rates are considerably higher for internal mammary and radial artery implantations than saphenous vein grafts. In patients with left anterior descending coronary artery obstruction, survival is better when coronary bypass involves the internal mammary artery rather than saphenous vein. Graft patency and outcomes are improved by meticulous treatment of risk factors, particularly dyslipidemia. Angina is abolished or greatly reduced in ~90 per cent of patients following complete revascularization.
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