What Are Coronary Spasms?
Spasm of the coronary arteries, also known as vasospastic angina, is thought to occur from hypersensitivity and hyperreactivity of the smooth muscle within the coronary arteries that impact constriction and dilation. In the case of vasospastic angina, the arteries constrict, leading to reduced flow and lower perfusion of heart muscle. The result is cardiac chest pain (angina).
The smooth muscle of the coronary arteries is under the influence of the autonomic nervous system (ANS), part of the homeostasis of circulation in general. In the ANS, sympathetic stimulation causes constriction and parasympathetic stimulation causes relaxation, and an imbalance in this regulation can result in vasospasm; alternately, an overstimulation from both increased sympathetic tone and vagal tone (parasympathetic) can provoke it. Other contributions to vasospasm of the coronary arteries include endothelial (inner arterial lining) abnormalities and inflammation.
The major risk factor for coronary vasospasm is cigarette smoking. Exercise does not usually provoke it, but other triggers include:
- Changes in activity of the ANS
- Toxicity of drugs, including ephedrine-based products, cocaine, marijuana, alcohol, and amphetamines
- Botulism (food/ingestion of botulinum toxin)
- Hypomagnesemia (magnesium deficiency)
- Interventional coronary angioplasty
- Allergies that evoke inflammatory mediators
Signs and Symptoms
Recurrent chest pain (angina) in vasospastic angina is indistinguishable from classic angina, except that
- It occurs primarily at rest, frequently from mid-night to morning
- Pain lasts from 5-15 minutes or longer
Like classic angina, vasospastic angina similarities include:
- Pain that is a vague discomfort rather than overt pain
- Episodes are gradual in onset and resolution
- Position or respiration do not affect it
- Pain is poorly localized
- There may be nausea, sweating, palpitations, dyspnea, or dizziness
How Can Coronary Spasms Be Diagnosed?
Diagnosis of coronary spasm begins with a history of recurrent vasospastic angina that causes episodic chest pain at rest. Since this symptom can be confused with non-vasospasm angina, a 12-lead ECG is necessary to rule out:
- ST segment changes typical of myocardial ischemia or previous infarction
- Obstructive coronary artery disease
If there is no evidence of obstructive coronary artery disease on ECG, an ambulatory ECG is necessary to identify those patients who may require coronary angiography.
A patient undergoing an investigation for coronary artery spasm should have a baseline ECG–one during a time in which there is no pain.
During anginal episodes from coronary vasospasm, an ECG using 12-lead protocol can usually identify ST segment elevations that occur during vasospastic episodes and then identify resolution of these after the pain resolves (<15 minutes). Such a scenario has good diagnostic accuracy for coronary arterial spasm. The ST segment elevation quickly returns to the baseline. If there is no transient ST segment elevation during the chest pain episodes, it is unlikely vasospasm.
Diagnosis of Vasospastic Angina
- Recurrent episodes of angina, generally at rest
- Transient ST segment elevation on ECG at the time of the angina
- Subsequent absence of ST segment elevation after episode resolution
The ECG, alternately, can indicate signs of ischemia in the heart muscle (myocardium) or previous myocardial infarction. For patients with angina who do not demonstrate ST segment changes during the chest pain episodes, coronary artery obstructive disease should be ruled out with a stress test. If the stress test rules out obstructive coronary artery disease, an ambulatory ECG should be done.
The ambulatory ECG is useful in the search for episodes of ST segment elevation/depression with or without angina. Transient ischemic ST changes in an ambulatory ECG may identify those with vasospasm for whom the non-ambulatory ECG was inconclusive or negative. If even an ambulatory ECG is inconclusive or negative, a 24-hour Holter monitor can be administered in which the patient can bookmark times of chest pain for comparison with the ECG recordings for correlation.
This is used when it is important to rule out obstructive coronary artery disease.
Management of Coronary Spasms
Management of coronary spasm (vasospastic angina) includes the following to reduce the frequency of episodes and the severity of complications:
- Alteration in lifestyle: smoking cessation
- Calcium channel blockers to prevent vasoconstriction in the coronary arteries, which reduces the pain
- Long-acting vasodilators (long-acting nitrates)
- Statins that, besides their efficacy in treating dyslipidemia, directly enhance endothelial nitric oxide for vasodilation and affect vascular smooth muscle
- Magnesium in cases of magnesium deficiency (hypomagnesemia)
Coronary Artery Spasm Complicated by Heart Disease
For the 25% of vasospasm angina patients who also experience myocardial infarction and serious arrhythmias, therapy for the vasospasm will impact the likelihood of these life-threatening events. Vasospasm is associated with the loosening and release of thrombotic emboli.
Palpitations may indicate an arrhythmia and is associated with syncope or presyncope. The type of arrhythmia is dependent on the area that suffers due to compromise of blood flow from the particular coronary artery or arteries. Spasm of the right coronary artery can negatively impact the function of the atrioventricular (AV) node; spasm of the anterior descending coronary artery can result in left ventricular ischemia and subsequent ventricular tachycardia.
Cardiac arrest associated with vasospastic angina should have an implantable cardioverter-defibrillator placed.
A cardioverter-defibrillator should also be used in patients with obstructive coronary artery disease and vasospastic angina who are already on calcium channel blockers.
Percutaneous coronary intervention (PCI) can be helpful if obstructive coronary disease is responsible for triggering vasospastic angina. Stenting, or if multi-vessel disease is present, coronary artery bypass (CABG) may be necessary.