13.1 Fulminant Myocarditis, Stress & Peripartum Cardiomyopathy, and Hypertrophic Cardiomyopathy

Fulminant Myocarditis

Myocarditis becomes a critical care problem when inflammation causes cardiogenic shock, high-grade conduction block, or ventricular arrhythmia. Patients are often young, with a viral prodrome, chest pain, and rapidly falling ejection fraction.

• Causes:
  • Viral: enterovirus and coxsackie, adenovirus, parvovirus B19, human herpesvirus 6, influenza, SARS-CoV-2.
  • Immune: giant cell myocarditis, eosinophilic (hypersensitivity) myocarditis, sarcoidosis, systemic lupus, and immune checkpoint inhibitor myocarditis.
  • Toxic: anthracyclines, 5-fluorouracil, cocaine, methamphetamine.
  • Bacterial and other: Lyme carditis, diphtheria, Chagas disease.
• Diagnosis:
  • Troponin is usually markedly elevated with a non-obstructive coronary angiogram.
  • Echocardiography shows global or regional dysfunction, sometimes with increased wall thickness from edema.
  • Cardiac MRI shows edema and late gadolinium enhancement, typically subepicardial.
  • Endomyocardial biopsy is indicated for fulminant presentations, because it identifies the subtypes that need immunosuppression.
• Management:
  • Standard cardiogenic shock care, but with a low threshold for temporary mechanical circulatory support (Impella, VA-ECMO), because many patients recover ventricular function within weeks.
  • Avoid NSAIDs; use guideline heart failure therapy once stabilized.
  • Treat arrhythmia aggressively; high-grade block may need temporary pacing, and definitive device decisions are deferred until recovery is assessed.
  • Specific immunosuppression:
    • Giant cell myocarditis: corticosteroids plus cyclosporine, often with azathioprine; untreated, it progresses to death or transplantation.
    • Eosinophilic myocarditis: stop the triggering drug and give corticosteroids.
    • Cardiac sarcoidosis: corticosteroids, with device therapy for conduction disease.
    • Lyme carditis: ceftriaxone, with temporary pacing for block that usually resolves.
  • Immune checkpoint inhibitor myocarditis: suspect it within the first few weeks of therapy, often with concomitant myositis and a high creatine kinase. Stop the drug permanently and give methylprednisolone 1,000 mg daily; escalate to abatacept, mycophenolate, antithymocyte globulin, or plasma exchange if there is no rapid improvement. Mortality is high, and conduction disease is common.

Stress (Takotsubo) Cardiomyopathy

• Triggers: emotional or physical stress, subarachnoid hemorrhage, status epilepticus, severe sepsis, catecholamine infusions, pheochromocytoma, and withdrawal states.
• Features:
  • Chest pain, dyspnea, or shock with ST elevation or deep T-wave inversion and marked QT prolongation.
  • Regional ballooning across more than one coronary territory, most often apical, sometimes midventricular or basal (the "reverse" variant).
  • A troponin rise that is modest relative to the extent of dysfunction, with a disproportionately high BNP.
  • Non-obstructive coronaries.
• Complications: dynamic left ventricular outflow obstruction, severe mitral regurgitation, apical thrombus, free wall rupture (rare), and ventricular arrhythmia from QT prolongation.
• Management: supportive. If there is outflow obstruction, avoid inotropes and use phenylephrine and fluids; otherwise standard heart failure therapy. Recovery within days to weeks is typical. Anticoagulate for apical thrombus or akinesis with high thrombus risk. Watch for recurrence.

Peripartum Cardiomyopathy

• Definition: new systolic dysfunction toward the end of pregnancy or in the months after delivery, without another cause.
• Risk factors: older maternal age, multiparity, preeclampsia and hypertensive disorders, multiple gestation, and African ancestry.
• Presentation: heart failure that mimics normal late-pregnancy symptoms, so diagnosis is often delayed; some present in cardiogenic shock or with arrhythmia.
• Management:
  • Before delivery, avoid ACE inhibitors, ARBs, ARNI, mineralocorticoid antagonists, and ivabradine. Hydralazine and nitrates control afterload, beta-1 selective beta-blockers (metoprolol) are used, and furosemide is given for congestion.
  • After delivery, use full guideline-directed therapy; ACE inhibitors such as enalapril and captopril, and beta-blockers, are compatible with breastfeeding.
  • Anticoagulation is recommended for an ejection fraction below about 30% in the peripartum period, because thrombosis risk is high.
  • Bromocriptine to suppress prolactin has shown benefit in trials and registries, and must be combined with anticoagulation; it precludes breastfeeding and remains individualized.
  • Severe shock needs mechanical circulatory support and transplant evaluation; many patients recover ejection fraction within 6 months.
  • Counsel that subsequent pregnancy carries substantial relapse risk, particularly if function has not normalized.

Hypertrophic Cardiomyopathy in the ICU

The problem is a small, stiff, hypercontractile ventricle with dynamic outflow obstruction worsened by anything that reduces cavity size: hypovolemia, vasodilation, tachycardia, and inotropes.

• Atrial fibrillation is poorly tolerated because the atrial kick is lost and rate rises. Cardiovert early, and anticoagulate (hypertrophic cardiomyopathy with atrial fibrillation is an indication regardless of the CHA2DS2-VASc score).
• Sudden cardiac death risk factors include unexplained syncope, massive wall thickness (30 mm or more), a family history of sudden death, nonsustained ventricular tachycardia, apical aneurysm, and extensive late gadolinium enhancement.
• Rescue options for refractory obstruction include disopyramide, septal reduction (myectomy or alcohol ablation), and cardiac myosin inhibitors in the outpatient setting.
• In hypertrophic cardiomyopathy with cavity obliteration and hypotension on the ventilator, the management is counterintuitive: fluid, pure vasoconstrictors, rate control, and sedation to reduce catecholamines, rather than inotropic escalation.