Stable angina

Ischemic cardiac chest pain is called angina pectoris.

 * Pre-exam preparation for medicine, HN Sarker

The types of angina are:

• Stable angina
• Unstable angina
• Prinzmetal’s angina
• Nocturnal or decubitus angina

 * Pre-exam preparation for medicine, HN Sarker

Prinzmetal’s angina (also known as variant angina), characterized by chest pain at rest that occurs in cycles, due to vasospasm and may be accompanied by spontaneous and transient ST elevation on the ECG.

 * Pre-exam preparation for medicine, HN Sarker

Cardiac syndrome X is the constellation of –

• typical angina on effort,
• objective evidence of myocardial ischemia on stress testing, and
• angiographically normal coronary arteries.

 * Pre-exam preparation for medicine, HN Sarker

Ischemia due to fixed atheromatous stenosis of one or more coronary arteries, i.e. demand led angina.

 * Pre-exam preparation for medicine, HN Sarker

Causes of angina are:

1. Impaired myocardial oxygen supply
   • Coronary artery disease, e.g. atherosclerosis
   • Coronary artery spasm
   • Congenital coronary artery disease
   • Severe anemia.
2. Increased myocardial oxygen demand
   • Left ventricular hypertrophy
     • Hypertension
     • Aortic valve disease
     • Hypertrophic cardiomyopathy
   • Tachyarrhythmias.

 * Pre-exam preparation for medicine, HN Sarker

* Davidson’s Principles and Practice of Medicine, 22nd edition Page: 584

The common causes of angina are:

• Coronary artery disease
• Aortic stenosis
• Hypertrophic cardiomyopathy

 * Pre-exam preparation for medicine, HN Sarker

The most common cause of angina is coronary atherosclerosis.

 * Pre-exam preparation for medicine, HN Sarker

Angina with normal coronary arteries are:

• Prinzmetal’s angina (variant angina)
• Syndrome X.

 * Pre-exam preparation for medicine, HN Sarker

A typical stable angina is a –

• retrosternal,
• choking or constricting chest pain,
• comes on with exertion,
• is relieved by rest or nitroglycerin,
• may radiate to jaw, neck or arms (more in left arm).

 * Pre-exam preparation for medicine, HN Sarker

Aggravating factors of angina are:

• Exertion
• Emotional excitement
• Cold weather
• Exercise after meals or heavy meals
• Anemia
• Thyrotoxicosis

 * Pre-exam preparation for medicine, HN Sarker

* Davidson’s Principles and Practice of Medicine, 22nd edition Page: 584

The relieving factors of angina are:

• Rest
• Glyceryl trinitrate
• Warm-up before exercise

 * Pre-exam preparation for medicine, HN Sarker

1. Resting ECG
2. Exercise ECG
3. Other forms of stress testing:
   • Myocardial perfusion scanning
   • Stress echocardiography
4. Coronary arteriography
5.  Others:¹
   • RBS and lipid profile
   • X-ray chest PA view
   • Thyroid function test

 * Davidson’s Principles and Practice of Medicine, 22nd edition Page: 584; ¹Pre-exam preparation for medicine, HN Sarker; Short and Long Cases in Clinical Medicine, HN Sarker Page: 265

1. Resting ECG
   • The ECG is often normal, even in patients with severe coronary artery disease.
   • The most convincing ECG evidence of myocardial ischemia is ST segment depression with or without T-wave inversion.
2. Exercise ECG:
   • Planar or down-sloping ST segment depression of ≥ 1 mm is indicative of ischemia.
   • Up-sloping ST depression is less specific and often occurs in normal individuals.

Planar ST depression is usually indicative of myocardial ischaemia.	Downsloping depression also usually indicates myocardial ischaemia.	Up-sloping depression may be a normal finding.

Figure: Forms of exercise-induced ST depression.

Figure: A positive exercise test (chest leads only). The resting 12-lead ECG shows some minor T-wave changes in the inferolateral leads but is otherwise normal. After 3 minutes’ exercise on a treadmill, there is marked planar ST depression in leads V4 and V5 (right offset). Subsequent coronary angiography revealed critical three-vessel coronary artery disease.

* Davidson’s Principles and Practice of Medicine, 22nd edition Page: 584

To detect anemia that precipitates angina.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 265

To detect thyrotoxicosis that precipitates angina.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 265

Stable angina.

A 58-year-old man, smoker, hypertensive presents with several episodes of retrosternal constricting chest pain which comes on exertion, relieved by rest and radiates to medial side of left arm.

He is a smoker, hypertensive (and has significant family history). So I consider this diagnosis.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 265

As pain persists for few minutes, comes on exertion and relieved by rest.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 265

As there is typical ischemic cardiac chest pain and there is no heartburn, retching and relation with food.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 265

Musculoskeletal pain is constant, not episodic, well localized, aggravated by deep inspiration and movement, not relieved by rest.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 265

General measures:

1. Lifestyle advice—Advice to patients with stable angina.
   • Do not smoke.
   • Aim for ideal body weight.
   • Take regular exercise (exercise upto, but not beyond, the point of chest discomfort is beneficial and may promote collateral vessels).
   • Avoid severe unaccustomed exertion and vigorous exercise after a heavy meal or in very cold weather.
   • Take sublingual nitrate before undertaking exertion that may induce angina.
2. Control of risk factors—Such as smoking, hypertension, and hyperlipidemia.

Drug therapy:

1. Antiplatelet therapy
   • Low-dose (75 mg) aspirin
   • Clopidogrel (75 mg daily), if aspirin causes troublesome dyspepsia or other side effects.
2. Antianginal drug treatment: Five groups of drugs are used to help relieve or prevent the symptoms of angina:
   • Nitrates, e.g. isosorbide dinitrate.
   • β-blockers, e.g. slow-release metoprolol 50–200 mg daily and bisoprolol 5–15 mg daily.
   • Calcium antagonists, e.g. verapamil and diltiazem.
   • Potassium channel activators, e.g. nicorandil.
   • I_f channel antagonist. (Ivabradine is the first of this class of drug.)

Invasive therapy:

1. Percutaneous coronary intervention (PCI)
2. Coronary artery bypass grafting (CABG).

Note:

Ivabradine acts on the I_f (f is for “funny”, so called because it had unusual properties compared with other current systems known at the time of its discovery) ion current, which is highly expressed in the sinoatrial node.¹

Figure: A scheme for the investigation and treatment of stable angina on effort. The selection of percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) depends upon patient choice, coronary artery anatomy and extent of coronary artery disease. In general, left main stem and three-vessel coronary artery disease should be treated by CABG surgery.

 * Pre-exam preparation for medicine, HN Sarker; * Davidson’s Principles and Practice of Medicine, 22nd edition Page: 585-588; ¹Wikipedia

Headache is the most common side effect of nitrate.

 * Pre-exam preparation for medicine, HN Sarker

We can treat it by using slow release preparation of nitrate and paracetamol may help.

 * Pre-exam preparation for medicine, HN Sarker

• Bronchial asthma,
• COPD,
• Advanced heart block,
• Peripheral vascular disease, and
• NYHA class III and IV heart failure.

 * Pre-exam preparation for medicine, HN Sarker

Common side effects of calcium channel blocker are:

• Constipation
• Fluid retention (edema)
• Calcium channel antagonist reduce myocardial contractility and can aggravate or precipitate heart failure.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 266

About 50% of patient develop edema, more with dihydropyridine than nondihydropyridine.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 266

Calcium channel blockers and nitrates.

 * Pre-exam preparation for medicine, HN Sarker

β-blocker is contraindicated in Prinzmetal’s angina.

 * Pre-exam preparation for medicine, HN Sarker

This is treated with antianginal therapy, usually with β- blocker.

 * Pre-exam preparation for medicine, HN Sarker