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.