Angina

Introduction

Angina is the chest pain or discomfort that occurs when a part of the heart muscle doesn’t receive enough oxygen to cover its requirements. Angina is a symptom of coronary artery disease, a condition with narrowings and blockages in heart arteries that hinder the adequate blood supply to the heart muscle. Angina may present as dull, tight or pressure-type pain in the chest which may radiate to jaw, neck, shoulders, arms or back. Onset of such pain is called “angina attack”. Triggering factors include physical activity and stress but angina can start at rest.

Causes of angina

Atherosclerosis (a type of cardiovascular disease) is the most common cause of angina where the blood vessels become hard and narrow due to the formation of fatty plaques which, in turn, prevent normal blood supply to the heart muscles and produce the symptoms of angina. Risk factors of atherosclerosis include age, smoking, diabetes mellitus, high blood pressure, high cholesterol, male gender, positive family history, physical inactivity and obesity.

Population at risk

Older adults are more prone to developing angina. Incidence of angina is higher in men than women. In England, one out of twelve men and one out of thirty women of age 55-64 years suffer from angina. However, incidence of angina is higher (one in seven men and one in twelve women) in the individuals above 65 years of age.

Complications of angina

Coronary atherosclerosis may progress and lead to more frequent anginal attacks or acute coronary syndromes including unstable angina and myocardial infarction (heart attack). People with angina are also at higher risk of peripheral vascular disease (atherosclerosis in leg arteries leading to intermittent claudication, i.e. cramps in legs during walking) and disease of carotid arteries leading to transitory ischaemic attacks (TIA, mini stroke) and strokes. These complications can be reduced considerably with life style modifications. Reduce obesity if you are obese, stop smoking if you smoke, go for a daily walk and eat healthy food.

Types of angina

There are two main types of angina:

  • 1. Stable angina
  • 2. Unstable angina

Stable angina

Stable angina is the most common type of angina that occurs during physical activity or mental stress once the degree of exertion or stress exceeds certain threshold. The underlying mechanism is the disbalance between oxygen supply to and demand of the heart muscle. It develops gradually over time and follows a relatively uniform pattern. For instance, the patient can experience chest pressure or squeezing while climbing stairs. The pain is usually promptly relieved by rest or by short-acting nitrates such as GTN (glyceryl trinitrate) spray. Stable angina itself is not a life-threatening condition; however, it indicates the presence of plaques in coronary arteries which predispose to a myocardial infarction. In other words, stable angina is not a “heart attack”; however, it may precipitate heart attack.

Unstable angina

Unstable angina is a serious type of chest pain that develops rapidly and usually occurs at rest. It may last for up to 30 minutes or more and may not respond to nitrate spray or tablets. Unstable angina may occur in the patients with previously known stable angina; however, it may happen also in those without any previous history of stable angina. Unstable angina is a type of acute coronary syndrome and it is a medical emergency as the ongoing lack of oxygen in the heart muscle may lead to heart attack. The treatment of unstable angina includes medication in the acute stage and revascularization in the long term with coronary angioplasty and coronary artery bypass surgery (CABG), discussed in more detail below. Variant or Prinzmetal’s angina (coronary artery spasm) and microvascular angina are other, less frequent types of angina.

Treatment of angina

Treatment of angina has three main goals:

  • Relief from symptoms during the anginal attack
  • Reduction in frequency of angina attacks
  • Prevention of heart attack

Several classes of medication including aspirin, beta blockers, calcium channel blockers, nicorandil, ivabradine, ranolazine and statins can be used to achieve the above three goals.

Invasive procedures may help when medicines fail to relieve the symptoms of angina. Invasive treatment of angina includes two types of interventions:

  • Percutaneous coronary intervention (PCI): In this catheter technique, a stent (tiny metallic tube) is passed to widen the narrowed section of the artery.
  • Coronary artery bypass graft (CABG): In this surgical technique, a portion of blood vessel from another part of the body is used to bypass the blood flow to thickened or blocked coronary arteries.

Prognosis

Only approximately 1% of patients with stable angina will suffer fatal heart attacks or stroke in any given year. 2.5% of patients may sustain non-fatal heart attack or stroke. Prognosis of unstable angina varies with the severity of the condition and is less favorable.