Group C

No Cause Identified (yet)

Sometimes tests don’t show a clear reason for the heart injury right away. That doesn’t mean nothing happened — it means the usual tests have not detected the cause yet. A plan for follow-up and the right timing of tests can still uncover answers.

1) What does “no cause identified” mean?

You meet criteria for a heart attack (rise and fall in troponin, the heart-injury blood test) and your coronary arteries were non-obstructed (less than 50% narrowed on the angiogram — the x-ray dye test of the heart arteries). After recommended tests, no single cause has been confirmed so far.

In many centres, extra tests (like OCT — a tiny camera inside the artery — and CMR, a detailed heart MRI) are used to find small plaque problems, inflammation, or stress-related changes that the first tests can miss.

2) Why might no cause be found at first?

Testing & timing

  • Timing matters: signs of swelling or tiny clots can fade; an early or delayed scan may miss them.
  • Scope of tests: specialist tests like vasospasm provocation (checks for artery tightening) or small-vessel flow measures aren’t always done during the first admission.
  • Access: advanced imaging may not be available 24/7 everywhere.

Biology & presentation

  • Small, short-lived plaque events can settle before imaging.
  • Problems in the small vessels (microvascular dysfunction or spasm) may come and go.
  • Some conditions mimic a heart attack (e.g., inflammatory myopericardial syndromes, Takotsubo) and need specific scans to confirm.

“No abnormality found” often means “no abnormality detected yet with the tests and timing used.”

3) Tests your team may consider

Core

  • ECG and heart-rhythm monitoring
  • Serial troponin to confirm a rise and fall pattern
  • Coronary angiogram (dye test) or CTCA (CT angiogram) if appropriate
  • CMR (cardiac MRI) within days — looks for inflammation, scarring, and reduced blood flow

Looking for hidden causes

  • OCT/IVUS — close-up views from inside the artery to spot plaque rupture/erosion or tiny clots
  • CFR/IMR — measures of small-vessel flow/resistance (microvascular dysfunction)
  • Vasospasm testing with acetylcholine in expert centres (checks if the artery over-tightens)

If still unclear

  • Repeat or later CMR if symptoms persist
  • Blood tests and scans for other triggers (e.g., anaemia, thyroid, infection, pulmonary embolism)
  • Targeted work-up for mimics (e.g., inflammatory conditions, Takotsubo)

Not everyone needs every test — choices depend on your story, risks, and local expertise.

4) How we manage things while we’re still looking

Medicines (individualised)

  • Statin and ACE inhibitor/ARB are often used to support artery and heart health.
  • Antiplatelet treatment depends on the level of suspicion for a small plaque event — balanced against bleeding risk.
  • For chest discomfort, a beta-blocker or calcium-channel blocker may help while we clarify the cause.

Your team will review and adjust medicines when a mechanism is confirmed.

Recovery & follow-up

  • Cardiac rehabilitation: guided activity, education, and confidence-building.
  • Plan for re-assessment if symptoms continue — sometimes the best test is at a later time.
  • Support for sleep, stress and mood — all of which affect symptoms and recovery.

5) What’s the outlook?

Many people do well, especially with rehabilitation and a clear follow-up plan. Ongoing symptoms can happen if the underlying issue (for example, small-vessel spasm) hasn’t been identified yet — but this is often treatable once found.

6) Quick FAQs

  • Does “no cause” mean nothing is wrong? No. The blood tests show heart injury. We may need different tests or better timing to find out why.
  • Should I keep taking my tablets? Yes, unless your clinician advises otherwise. They may change as we learn more.
  • What if symptoms return? Seek medical advice. A repeat or different test may now reveal the cause.

7) What we’re still learning

  • The best timing and mix of tests (OCT, CMR, spasm testing) for different patient stories.
  • Clear, standard pathways for persistent “unexplained” cases.
  • How to support wellbeing when the diagnosis is uncertain.

Research & support

You can help shape future care by joining registries or studies. Visit our research hub and connect with others in the community forum.