Acute Stent Thrombosis: A Bedside Reference for Clinicians

It is a Sunday evening. A 58-year-old man who had two drug-eluting stents placed in his left anterior descending artery eleven days ago arrives in your emergency department with crushing pain that began forty minutes ago, cold peripheries and 4 mm of ST elevation in V2 to V4. The nearest catheterisation laboratory is ninety minutes away by road and the interventional team is not yet contactable. This is the situation most doctors in international practice actually face when stent thrombosis walks through the door: no on-site angiography, incomplete records from the index procedure, and a patient who is deteriorating while you assemble the picture. What follows is a decision-led reference for those first two hours, and for the paperwork that has to follow.

Recognising the event under pressure

Stent thrombosis behaves differently from de novo plaque rupture. The occlusion is abrupt and total, there is no collateral conditioning, and the clinical presentation is skewed towards large-territory ST elevation, malignant arrhythmia and out-of-hospital arrest. Mortality at thirty days after a confirmed event is high enough that this diagnosis should sit at the top of your differential in any patient with recent coronary intervention and new severe chest pain, even when the pain has atypical features. Contemporary platforms have pushed the event rate well under one per cent of procedures, which paradoxically makes the diagnosis easier to miss.

Two things narrow the field quickly. First, an ECG that localises to the previously treated territory. Second, a timeline: the interval between the index procedure and the symptom onset tells you more about mechanism than any single investigation available to you at that moment.

The decision points

1. Confirm the territory before you commit

Compare the current tracing with the post-procedure ECG if you can obtain it, including from the patient’s phone photographs, which are often easier to retrieve than hospital records. New ST elevation in the stented distribution, or new regional wall motion abnormality on a bedside study, converts suspicion into a working diagnosis. A completely normal ECG ten minutes into severe pain should make you consider aortic dissection, oesophageal rupture and pulmonary embolism before you commit a patient to potent antithrombotic loading.

2. Place the event in its timing band, then infer the mechanism

Events within the first twenty-four hours are overwhelmingly mechanical: underexpansion, edge dissection, geographic miss, or a stent margin landing in residual disease. Events between one day and one month usually combine a mechanical substrate with an antiplatelet problem. Beyond a year, the dominant substrates are neoatherosclerosis inside the stent, acquired late malapposition and persistently uncovered struts. This inference matters even before angiography, because it tells you how hard to push on the drug history and how strongly to argue for intravascular imaging when you refer.

3. Take a forensic antiplatelet history

Ask when the last dose of each agent was taken, not whether the patient is compliant. Look specifically for interruption before dental or endoscopic procedures, a pharmacy substitution, vomiting after dosing, and recent opiate administration, which delays oral absorption enough to matter in the first hours. In patients on clopidogrel, a poor-metaboliser CYP2C19 genotype remains a real contributor where potent agents were avoided for cost or bleeding reasons. Record the answers verbatim; they will shape the discharge regimen more than anything else you do tonight.

4. Load, anticoagulate, and start the clock towards a catheterisation laboratory

Emergency angiography with a view to intervention is the treatment. Everything you give before transfer is a bridge. Current guidance favours a potent oral P2Y12 inhibitor over clopidogrel in this setting, given parenterally or intravenously where formulations allow, alongside full anticoagulation and aspirin if the patient is not already loaded. Where a cannulated intravenous P2Y12 agent is available, it removes the absorption uncertainty entirely. Glycoprotein IIb/IIIa inhibition is a reasonable bridging decision in a haemodynamically compromised patient with a very high thrombus burden and no bleeding contraindication, and should be discussed with the receiving operator rather than started unilaterally.

5. Be honest about fibrinolysis

Lytic therapy performs poorly against platelet-rich thrombus organised on a metallic scaffold, and it does nothing about the mechanical substrate underneath. If transfer will genuinely exceed the window and the patient is deteriorating, fibrinolysis is defensible as a rescue manoeuvre, but plan for it to be a partial success at best and continue to push for angiography. Say so explicitly when you refer.

6. Insist that the mechanism is found, not just the vessel opened

Restoring flow without identifying why the stent occluded invites a repeat event. Intravascular imaging with either ultrasound or optical coherence tomography changes management in a substantial proportion of these cases, identifying underexpansion, unrecognised dissection at the stent margin, protruding tissue or neoatherosclerotic rupture. When you refer, ask for imaging by name. Optimisation of an underexpanded segment with high-pressure non-compliant balloon dilatation is frequently a better answer than adding another layer of metal, and readers who work alongside interventional colleagues will find the technical detail set out in our advanced PCI techniques reference and in the case-based catheterisation laboratory complications volume.

7. Decide the long-term antithrombotic strategy before discharge

A patient who has thrombosed a stent while on treatment has declared a phenotype. Escalation to a potent P2Y12 inhibitor, prolonged rather than abbreviated dual therapy, and reassessment of any concurrent anticoagulation indication are the usual conclusions. Where an oral anticoagulant is also required, the balance struck in the AUGUSTUS and PIONEER AF-PCI programmes still frames the discussion: short triple therapy, then a dual regimen, with the P2Y12 agent retained. Weigh this against a formal bleeding assessment using PRECISE-DAPT or HAS-BLED rather than an impression, and grade any subsequent bleeding with the BARC scale so that later decisions rest on a common language.

When to escalate, transfer or call for help

• Immediately, in parallel with resuscitation: cardiogenic shock, sustained ventricular arrhythmia, or arrest with return of circulation. These patients need a laboratory with mechanical circulatory support, not the nearest laboratory.
• Within the primary intervention window: any confirmed or strongly suspected event with ongoing ST elevation. Aim for a door-in to door-out interval under thirty minutes and hand over the index procedure details with the patient.
• Urgently but not emergently: recurrent rest angina without ST elevation after recent stenting. Subacute events can present with a stuttering pattern before occluding; these patients should not wait for an outpatient appointment.
• For a second opinion: any patient in whom you are considering interrupting antiplatelet therapy for surgery within six months of stenting. That conversation belongs with the implanting operator, and our interventional cardiology reference collection is a reasonable starting point for the discussion.

What to document

The record you write becomes the only reliable account of the event once the patient moves institutions, which in international practice is likely. Capture the following.

• Certainty category using the Academic Research Consortium framework: definite when thrombus is confirmed angiographically or at autopsy, probable when there is unexplained death within the first month or an infarction in the stented territory without angiographic confirmation, possible for unexplained death thereafter. Write the term, not a paraphrase.
• Timing band in days from the index procedure, with the index procedure date stated.
• Index procedure detail: vessel, stent platform, nominal diameter and length, post-dilatation pressures, and whether intravascular imaging was used.
• Antiplatelet timeline: agents, doses, last dose taken, any interruption and its reason.
• What you gave and when, including loading doses, anticoagulant, and the time reperfusion therapy was initiated.
• Bleeding events graded on the BARC scale, and the bleeding risk score used at discharge.

Bench card

Three quick correctables to run through at the bedside: absorption (vomiting, opiates, recent surgery), agent (clopidogrel in a likely poor metaboliser), adherence (cost, supply, an interruption nobody documented). For structured revision across the wider acute coronary field, see the cardiology reference library, the acute coronary syndromes handbook and the cath lab reference collection. The original examination-oriented treatment of this topic remains available as acute stent thrombosis board revision notes.

Questions from the floor

Can I exclude stent thrombosis if troponin is only mildly elevated at presentation?

No. Very early in an occlusive event the biomarker has not yet risen, and a reassuring first troponin in a patient with recent stenting and ongoing pain is a trap. Treat the ECG and the clinical picture; repeat the biomarker only to characterise the event afterwards.

The patient stopped their P2Y12 inhibitor two days ago for a dental extraction. Does that change management?

It changes the explanation, not the acute pathway. Reload, anticoagulate and refer as you would otherwise. It should, however, prompt a written plan for future procedural interruptions and a note to the dentist and the primary physician.

Is thrombus aspiration expected in these cases?

Routine aspiration in primary intervention fell out of favour after the large randomised trials, but selective use in a heavily thrombotic occluded stent remains a legitimate operator decision. It is not a substitute for finding the underlying mechanical problem.

How long should dual antiplatelet therapy continue after a confirmed event?

Longer than the standard course, and with a potent agent unless bleeding risk forbids it. Abbreviated strategies of the kind tested in TWILIGHT and MASTER DAPT were designed for bleeding-vulnerable patients without a thrombotic event, and do not transfer to a patient who has already occluded a stent.

Reviewed by Dr A M Thirugnanam, MD, MSICP, FSCAI, Ph.D., Senior Interventional Cardiologist — written from two decades of managing acute stent failure in patients who first present far from an interventional service.