What is the most likely cause of sudden hypotension a few hours after percutaneous coronary intervention and what emergent treatment should be initiated?

Acute Stent Thrombosis After PCI

Sudden hypotension within hours of percutaneous coronary intervention is most likely caused by acute stent thrombosis, and the patient requires immediate return to the catheterization laboratory for emergency coronary angiography and repeat PCI.

Most Likely Cause: Acute Stent Thrombosis

Acute stent thrombosis occurs in approximately 1.7% of patients within 24 hours of PCI and presents with sudden hemodynamic collapse, recurrent chest pain, or ST-segment elevation. 1 The timing—within hours of the procedure—is pathognomonic for this complication rather than subacute thrombosis (which peaks at 5-7 days post-procedure). 2

Key Clinical Features

• Acute stent thrombosis carries a 70-90% risk of Q-wave myocardial infarction and 7-20% mortality. 2
• Hypotension in this setting reflects cardiogenic shock from acute vessel occlusion and extensive myocardial injury. 3
• The condition is a true cardiovascular emergency requiring recognition within minutes, not hours.

Emergent Treatment Algorithm

Immediate Actions (Within Minutes)

1. Obtain a 12-lead ECG immediately to confirm acute vessel closure—look for new ST-segment elevation in the territory of the stented vessel. 4

2. Activate the catheterization laboratory for emergency coronary angiography; this is a Class I, Level A recommendation for patients developing cardiogenic shock within 36 hours of acute MI. 3

3. Administer aspirin 162-325 mg (chewed) if not already given, and ensure dual antiplatelet therapy is on board. 5

4. Start unfractionated heparin bolus (60-70 U/kg, maximum 5000 U) followed by infusion (12-15 U/kg/h targeting aPTT 50-70 seconds). 5

Hemodynamic Support

• Consider intra-aortic balloon pump support immediately in the context of systemic hypotension and/or severe LV dysfunction, as flow in stented vessels is pressure-dependent. 3

• Emergency revascularization with PCI in patients <75 years with cardiogenic shock within 18 hours of shock onset provides significant 6-month survival benefit. 3

Catheterization Laboratory Management

Emergency PCI with balloon angioplasty is the definitive treatment for acute stent thrombosis and successfully relieves ischemia in the majority of patients. 3 The goals are:

• Restore TIMI grade 3 flow through the thrombosed stent 3
• Assess for mechanical causes: incomplete stent expansion, residual dissection, or undersizing 1
• Consider adjunctive GP IIb/IIIa inhibitor (eptifibatide or abciximab) for visible thrombus 3, 6

Specific Risk Factors Present in This Case

The following procedural factors dramatically increase acute stent thrombosis risk and should be assessed during emergency angiography:

• Postprocedural dissection (strongest predictor) 1
• Stent undersizing or incomplete expansion 1
• Smaller stent diameter (<3 mm) 1
• Angiographically visible thrombus after initial implantation 2
• Poor distal runoff 2

Critical Antiplatelet Considerations

Immediate Assessment

• Verify that the patient received adequate loading doses: clopidogrel 300-600 mg OR ticagrelor 180 mg OR prasugrel 60 mg at the time of initial PCI. 5, 4

• Lack of clopidogrel therapy is the strongest predictor of subacute thrombosis, but inadequate loading can precipitate acute events. 1

GP IIb/IIIa Inhibitor Dosing

If eptifibatide is chosen for adjunctive therapy during emergency PCI:

• Bolus: 180 mcg/kg IV, followed by infusion of 2 mcg/kg/min (reduce to 1 mcg/kg/min if CrCl <50 mL/min). 6
• Continue infusion until hospital discharge or up to 18-24 hours. 6

Differential Considerations (Less Likely but Must Exclude)

While acute stent thrombosis is the primary concern, rapidly assess for:

• Mechanical complications: Acute mitral regurgitation or ventricular septal rupture (perform urgent echocardiography if time permits before catheterization). 5
• Coronary perforation or tamponade: Rare but catastrophic; suggested by persistent hypotension despite revascularization.
• Heparin-induced thrombocytopenia (HIT): Unusual within hours but can cause acute thrombosis; check platelet count immediately. 7

Common Pitfalls to Avoid

• Never attribute hypotension to anxiety, vasovagal reaction, or "post-procedure fatigue" without first obtaining an ECG and excluding acute vessel closure. 4

• Never delay catheterization laboratory activation to "stabilize" the patient medically—definitive revascularization is the only effective treatment for cardiogenic shock due to stent thrombosis. 3

• Never assume adequate antiplatelet therapy was given; verify loading doses and consider clopidogrel resistance or non-compliance as contributing factors. 8, 1

• Never use thrombolytics as first-line therapy for suspected stent thrombosis—emergency PCI is superior and avoids hemorrhagic complications. 3

Post-Resuscitation Management

After successful emergency PCI:

• Continue dual antiplatelet therapy for a minimum of 12 months. 4
• Monitor serial troponins to track evolving myocardial injury. 9
• Enroll in cardiac rehabilitation immediately—this is a Class I recommendation that reduces mortality by 20%. 4, 9
• Verify platelet count within 24 hours to exclude thrombocytopenia (immune-mediated or HIT). 6, 7