Medical management of stable angina

Medical management of stable angina

Medical management of stable angina

Aims of treatment

Aims of treatment in the management of stable angina are the prevention of myocardial infarction and death and to minimise or abolish symptoms. The former can be achieved by reducing the plaque progression, stabilizing the plaque and prevention of thrombosis if endothelial dysfunction or plaque rupture occurs.

General management and non-pharmacological considerations

These include smoking cessation, moderation of alcohol, switching over to a diet mainly of vegetables, fruit, fish and poultry. Weight reducing diet is needed if the person is overweight. Physical activity to be encouraged to the extent permissible by the disease status. Concomitant disorders to be managed. Patients with diabetes and /or renal disease should be treated with a blood pressure goal of <130/60 mmHg.

Management of an acute attack

Rest from provoking activity most often relieves the pain in chronic stable angina. Use of sublingual nitrates is very popular for acute relief. But patients should be seek medical advise if symptoms persist for more than 10-20 min after rest and / or not relieved by sublingual nitrates. Any person prescribed nitrates should be informed about the potential side effects of nitrates including headache due to vasodilation of extracranial vessels and occasional syncope, again due to peripheral vasodilation.

Pharmacological therapy to improve prognosis of chronic stable angina

Antithrombotic drugs

Low-dose aspirin (75 – 150 mg/day) should be given to all without contraindications like active gastrointestinal bleeding, aspirin allergy or intolerance. Clopidogrel or ticagrelor as an alternative in patients who cannot take aspirin should be considered.

ACE inhibitors

Angiotensin converting enzyme inhibitors should be given to all those with coincident indications for ACEI (e.g. hypertension, heart failure). ACE inhibitors are also useful in those with a myocardial infarction for prevention of ventricular remodeling.

Beta-blockers

Beta-blockers are given to all patients post myocardial infarction for secondary prevention and in those with heart failure. Beta blockers have also a important role in symptom relief of angina.

Lipid-lowering drugs

Statin therapy should be considered for all patients with coronary artery disease. High dose statin therapy may be useful in high risk patients with proven coronary artery disease. Fibrate therapy is given to those with low HDL an high triglycerides who have diabetes / metabolic syndrome.
Fibrate/ nicotinic acid as adjunctive therapy to statin is given in patients with low HDL and high triglyceride who are at high risk.

Pharmacological agents to reduce symptoms and ischaemia

Nitrates

Nitrates acts predominantly by vasodilatation and hence decreasing the preload of the heart. Arteriolar dilatation decreases the afterload to some extend. Sublingual administration is useful to treat an acute attack and for situational prophylaxis in situations where the occurrence of angina is predictable. Oral or transdermal preparations are usually long acting and care has to be taken to maintain a nitrate-free period to prevent the occurrence of nitrate tolerance. A word of caution is needed to avoid nitrates in those who are on phosphodiesterase inhibitors like sildenafil.

Beta blockers

Beta blockers decrease the myocardial oxygen demand by decreasing the heart rate, contractility and blood pressure. Dosage has to be titrate dose to reduce symptoms and the heart rate. Beta blockers reduce symptoms and improve exercise tolerance, but may worsen vasospastic angina.

Calcium channel blockers

Calcium channel blockers produce systemic and coronary vasodilatation by inhibition of L-type calcium channels. Verapamil and diltiazem reduce contractility, heart rate and AV conduction. They reduce symptoms and improve exercise tolerance and are comparable to beta-blockers in efficacy. Calcium channel blockers are effective in vasospastic angina, unlike beta blockers.

Potassium channel activators

Drugs like nicorandil act by activating the potassium channels. They also have nitrate like vasodilator effects. Nicorandil has been shown to reduce death, myocardial infarction and hospitalization for angina.

Sinus node inhibitor

Ivabradine is the first selective and specific I_f current (pacemaker current of the sinus node) inhibitor, which reduces the heart rate via direct inhibition of I_f channel in sinus node. Sinus node inhibitors are as effective as beta blockade in reducing symptoms.

Metabolic agents for treatment of angina

These agents increase glucose utilization relative to fatty acid metabolism in the myocardium which is less oxygen intensive in terms of number of oxygen molecules required per molecule of ATP produced. They have limited hemodynamic effects and can be used in those with lower heart rate and blood pressure. The important agents in this group are trimetazidine and ranolazine.