Does Acute Coronary Syndrome (ACS) pain come and go?

Characteristics of Acute Coronary Syndrome (ACS) Pain

ACS pain typically presents as prolonged (>20 minutes) chest pain at rest, but it can come and go, particularly in unstable angina and early presentations of NSTEMI, which is why patients should never ignore intermittent chest pain. 1

Pain Patterns in ACS

Typical Presentation

• Retrosternal pressure or heaviness ("angina") that may radiate to the left arm, neck, or jaw 1
• Pain is most commonly prolonged (>20 minutes) at rest 1
• Can be intermittent, especially in unstable angina 1
• May be exacerbated by physical exertion and relieved at rest 1

Variable Patterns

• Unstable angina often presents with pain that comes and goes, with episodes that may:
  • Be new onset (de novo) angina
  • Represent destabilization of previously stable angina (crescendo angina)
  • Occur at rest or with minimal exertion 1
• NSTEMI can present with intermittent pain before developing into more persistent symptoms 1
• STEMI typically presents with persistent pain but may have been preceded by intermittent episodes 1

Clinical Significance of Intermittent Pain

The intermittent nature of chest pain does not exclude ACS and should be taken seriously for several reasons:

• Intermittent pain may represent:
  • Early stages of plaque rupture with transient thrombosis
  • Coronary vasospasm
  • Dynamic obstruction with intermittent ischemia 1, 2
• Patients with unstable angina frequently experience pain that comes and goes before developing into a full myocardial infarction 1
• The European Society of Cardiology guidelines specifically note that ACS pain "may be intermittent (usually lasting several minutes) or persistent" 1

Atypical Presentations

It's important to recognize that ACS may present atypically, especially in:

• Elderly patients (≥75 years)
• Women
• Patients with diabetes
• Patients with renal insufficiency
• Patients with dementia 1, 2

Atypical presentations include:

• Epigastric pain
• Indigestion-like symptoms
• Isolated dyspnea (most common angina equivalent)
• Unexplained fatigue
• Syncope 1

Diagnostic Approach for Intermittent Chest Pain

When evaluating patients with intermittent chest pain:

1. Obtain ECG within 10 minutes of presentation or during symptoms 1

   • Even transient ST-segment changes are significant
   • Serial ECGs may be necessary to capture dynamic changes

2. Measure cardiac troponins

   • Initial measurement upon presentation
   • Repeat in 1-2 hours for high-sensitivity troponin or 3-6 hours for conventional troponin 1
   • Elevated troponins may indicate myocardial damage even with intermittent symptoms

3. Risk stratification

   • Use validated tools like HEART, TIMI, or GRACE scores 1, 2
   • Consider the pattern, frequency, and triggers of pain episodes

Common Pitfalls and Caveats

• Do not dismiss intermittent chest pain as non-cardiac or less serious than persistent pain
• Do not rely solely on pain characteristics to rule out ACS - ECG and troponin testing are essential
• Do not delay evaluation of patients with intermittent chest pain, as this may represent unstable angina which can progress to myocardial infarction
• Be aware that pain relief with nitrates is not specific for cardiac pain and should not be used to rule out ACS 1
• Remember that a normal ECG does not exclude ACS, as 1-6% of confirmed cases may have normal ECGs 2

Summary

ACS pain can indeed come and go, particularly in unstable angina and early presentations of NSTEMI. The intermittent nature of chest pain should not reassure clinicians or patients, as it may represent a dynamic coronary process that could progress to complete occlusion and myocardial infarction. Any chest pain suspicious for ACS warrants prompt evaluation with ECG and cardiac biomarkers, regardless of whether the pain is persistent or intermittent.