What are the potential complications after a ST-Elevation Myocardial Infarction (STEMI)?

Complications After STEMI

STEMI can result in a spectrum of life-threatening complications that require immediate recognition and intervention, with mechanical complications, heart failure, arrhythmias, and thrombotic events being the most critical to monitor and manage.

Mechanical Complications

Cardiac rupture represents one of the most catastrophic complications following STEMI 1:

• Acute free wall rupture presents with cardiovascular collapse and electromechanical dissociation (continuing electrical activity without cardiac output), is usually fatal within minutes, and rarely allows time for surgical intervention 1
• Subacute free wall rupture occurs in 25% of rupture cases with a more gradual presentation 1
• Ventricular septal defect (VSD) typically occurs within the first 24 hours and presents with sudden onset heart failure or a new murmur, requiring urgent echocardiographic diagnosis and surgical intervention 1, 2
• Papillary muscle rupture causing acute mitral regurgitation presents similarly with sudden heart failure and new murmur 1

Echocardiography is the key diagnostic tool and should be performed to assess myocardial damage extent and identify these mechanical complications 1.

Heart Failure and Cardiogenic Shock

Heart failure severity is classified using the Killip classification 1:

• Class I: No rales or third heart sound
• Class II: Pulmonary congestion with rales over <50% of lung fields or third heart sound
• Class III: Pulmonary edema with rales over >50% of lung fields
• Class IV: Cardiogenic shock

Killip class III and IV patients require 1:

• Oxygen administration with pulse oximetry monitoring
• Regular blood gas checks
• Early consideration of continuous positive airway pressure or endotracheal intubation with ventilatory support
• Non-invasive ventilation should be considered as early as possible

Cardiogenic shock (Killip IV) is characterized by clinical signs of poor tissue perfusion (oliguria, decreased mentation), hypotension, small pulse pressure, tachycardia, and pulmonary edema 1. Patients with CS post-STEMI have significantly higher mortality (52%) compared to those without CS (11.76%) 3. Reduced left ventricular ejection fraction and elevated CK-MB levels are independent predictors of in-hospital mortality in STEMI patients with cardiogenic shock 3.

Arrhythmic Complications

Arrhythmias are common and require continuous monitoring 1. The ACC/AHA guidelines emphasize monitoring for arrhythmias as part of general measures in heart failure management 1. Anxiety has been demonstrated to predict in-hospital recurrent ischemia and arrhythmias 1.

Thrombotic and Embolic Complications

Left Ventricular Thrombus and Systemic Emboli

Intraventricular thrombi occur especially in patients with large anterior infarctions 1:

• Echocardiography may reveal intraventricular thrombi, particularly in anterior STEMI
• Mobile or protuberant thrombi should be treated initially with intravenous unfractionated heparin or LMWH, followed by oral anticoagulants for at least 3-6 months 1
• Contemporary data shows a low incidence (1.5%) of early LVT following STEMI in the primary PCI era, with 90% occurring in anterior STEMI 4
• Patients with cardiac source of embolism (atrial fibrillation, mural thrombus, or akinetic segment) should receive moderate-intensity warfarin (INR 2-3) in addition to aspirin for at least 3 months for LV mural thrombus or akinetic segment, and indefinitely for persistent atrial fibrillation 1

Deep Vein Thrombosis and Pulmonary Embolism

These complications are now relatively uncommon except in patients kept in bed due to heart failure 1:

• Prevention: Prophylactic doses of LMWH and compression stockings in high-risk patients 1
• Treatment: Therapeutic doses of LMWH for minimum of 5 days until adequately anticoagulated with warfarin (INR 2-3) 1
• Patients hospitalized for prolonged periods, unable to ambulate, or at high risk for DVT should receive low-dose heparin prophylaxis, preferably with LMWH 1

Ischemic Stroke

Ischemic stroke risk assessment is reasonable in all STEMI patients 1:

• Patients with acute ischemic stroke should receive neurological consultation 1
• Evaluation should include echocardiography, neuroimaging, and vascular imaging studies to determine stroke cause 1
• Patients with acute ischemic stroke and persistent atrial fibrillation should receive lifelong moderate-intensity warfarin therapy (INR 2-3) 1

Recurrent Ischemia and Reinfarction

Recurrent ischemic-type chest discomfort requires escalation of medical therapy 1:

• Intravenous anticoagulation should be initiated if not already accomplished 1
• Patients with signs of hemodynamic instability, poor LV function, or large area of myocardium at risk should be referred urgently for cardiac catheterization with revascularization as needed 1
• Insertion of intra-aortic balloon pump should be considered 1
• Patients considered candidates for revascularization should undergo coronary arteriography and PCI or CABG as dictated by anatomy 1

Pericarditis

Acute pericarditis may complicate STEMI with transmural necrosis 1:

• Pain is distinguished by its sharp nature and relationship to posture and respiration
• Diagnosis confirmed by pericardial rub
• Treatment: High-dose intravenous aspirin (1000 mg/24h) or NSAIDs if pain is troublesome 1
• Hemorrhagic effusion with tamponade is uncommon but particularly associated with antithrombin treatment, requiring pericardiocentesis if hemodynamic compromise occurs 1

Right Ventricular Infarction

Characterized by high jugular venous pressure, poor tissue perfusion or shock, bradycardia, and hypotension 1. This represents a distinct hemodynamic state requiring specific management considerations.

Bleeding Complications

Major bleeding occurred in 2.8% of >40,000 patients with acute MI in the GRACE Registry, with patients experiencing major bleeding having significantly higher in-hospital mortality (20.9% vs 5.6%) 1:

• Risk factors: Patient comorbidities, older age, female sex, low body weight, prior stroke, hypertension on presentation, renal insufficiency, anemia 1
• Intracranial hemorrhage (ICH) has a 65% mortality rate and overall incidence of 0.6% in fibrinolysis-treated patients 1
• Management of ICH: Stop all antiplatelet and anticoagulant therapy, obtain emergency neurological/neurosurgical consultation, consider protamine, fresh frozen plasma, prothrombin complex concentrates, activated factor VII, and platelets 1
• Vascular access site bleeding is the most common type, particularly after PCI 1

Psychosocial Complications

Depression and anxiety are prevalent in STEMI patients 1:

• Depression occurs in 25-75% of stroke patients and negatively impacts rehabilitation and functional outcomes 5
• Psychosocial status should be evaluated during hospitalization and at follow-up, including symptoms of depression, anxiety, sleep disorders, and social support environment 1
• Treatment: Cognitive-behavioral therapy combined with selective serotonin reuptake inhibitors improves outcomes (Level of Evidence: A) 1, 5
• Anxiolytic medications are reasonable for short-term anxiety or altered behavior related to hospitalization 1

No-Reflow Phenomenon

Prevention and treatment strategies include 1:

• Thrombus aspiration (Class IIa, Level B)
• Abciximab 0.25 mg/kg bolus and 0.125 mg/kg/min infusion for 12-24 hours (Class IIa, Level B)
• Adenosine: 70 mg/kg/min IV over 3 hours during and after PCI (Class IIb, Level B)