How is vasospastic angina diagnosed?

Diagnosing Vasospastic Angina

The diagnosis of vasospastic angina requires documenting transient ischemic ST-segment changes during an angina attack (usually at rest), with confirmation through ECG monitoring or provocative testing in patients with normal or non-obstructive coronary arteries. 1

Clinical Presentation and Initial Assessment

• Characteristic symptoms:

  • Chest pain occurring predominantly at rest (especially early morning)
  • Pain that resolves spontaneously or rapidly with nitrates
  • Preserved exercise tolerance
  • Possible circadian variation with most attacks in early morning 1

• Risk factors:

  • Smoking (most prominent risk factor)
  • Electrolyte disturbances (potassium, magnesium)
  • Cocaine or methamphetamine use
  • Cold exposure
  • Emotional stress
  • Hyperventilation 1

Diagnostic Algorithm

Step 1: ECG Documentation

• Obtain ECG during angina episodes (Class I recommendation) 1
• Look for:
  • Transient ST-segment elevation (classic in Prinzmetal angina)
  • ST-segment depression
  • T-wave changes 1

Step 2: Ambulatory ECG Monitoring

• 12-lead ambulatory ECG monitoring should be considered (Class IIa) 1
• Extended Holter monitoring (>1 week) may be necessary
• Focus on identifying ST-segment shifts at normal heart rate 1

Step 3: Coronary Imaging

• Invasive coronary angiography or coronary CTA is recommended (Class I) to:
  • Rule out obstructive coronary disease
  • Determine extent of underlying atherosclerosis
  • Document spontaneous spasm (rare but diagnostic) 1

Step 4: Provocative Testing

• Intracoronary provocation test should be considered (Class IIa) when:

  • Clinical suspicion is high
  • Non-invasive tests are inconclusive
  • Coronary arteries appear normal or have non-obstructive lesions 1

• Provocative agents:

  • Acetylcholine (most commonly used)
  • Ergonovine
  • Methylergonovine 1

• Positive test criteria (all three required):

  • Anginal symptoms
  • Ischemic ECG changes
  • Severe vasoconstriction of epicardial vessel 1

Important Considerations and Caveats

1. Safety precautions for provocative testing:

   • Avoid in patients with significant left main disease
   • Avoid in advanced 3-vessel disease
   • Avoid with high-grade obstructive lesions
   • Avoid in significant valvular stenosis
   • Avoid in LV dysfunction or advanced heart failure 1

2. Differential diagnosis:

   • Obstructive coronary artery disease
   • Microvascular angina
   • Stress cardiomyopathy (Takotsubo)
   • Non-cardiac chest pain 1

3. Prognostic factors:

   • Prognosis depends on extent of underlying CAD
   • Mortality is higher in patients with spasm superimposed on stenotic lesions
   • Complications include arrhythmias, syncope, MI, and sudden death 1

Therapeutic Considerations

Once diagnosed, vasospastic angina is treated primarily with:

• Calcium channel blockers (first-line therapy)
• Long-acting nitrates
• Risk factor modification (especially smoking cessation)
• Statin therapy 1, 2

Amlodipine specifically has been demonstrated to block coronary spasm by inhibiting calcium ion influx across cell membranes, making it effective for vasospastic (Prinzmetal's) angina 2.

Common Pitfalls to Avoid

1. Underdiagnosis: Vasospastic angina remains underdiagnosed as provocative tests are rarely performed 3

2. Misdiagnosis as STEMI: VSA can mimic acute coronary syndrome, leading to unnecessary interventions

3. Inadequate monitoring: Short-duration ECG monitoring may miss transient changes due to self-limiting nature of attacks 1

4. Overlooking in young patients: While more common in middle-aged adults, VSA can occur in younger patients, including women 4

5. Missing concomitant atherosclerosis: A substantial proportion of patients with vasospastic angina also have obstructive coronary disease 1

By following this diagnostic approach, clinicians can accurately identify vasospastic angina and initiate appropriate treatment to reduce morbidity and mortality associated with this condition.