Giant-cell myocarditis presenting in shock — case discussion

Presentation

Practice case (not a real patient). A 42-year-old woman presents with 10 days of new breathlessness. Echocardiography shows a normal-sized left ventricle with an LVEF of 25%. Troponin and NT-proBNP are raised.^[1] She has no previous cardiac history, coronary angiography shows no obstructive coronary artery disease, and no other cause for her new heart failure is found.^[1] On day 2 she develops sustained ventricular tachycardia, then complete heart block, and her blood pressure falls despite inotropes.^[1]

Step 1 — How sick is she, and where should she be?

Discussion:

• She is high risk in ESC 2025 Table 7: acute HF/cardiogenic shock, sustained VT, high-level AV block and newly reduced LVEF (<40%).^[1]
• ESC 2025 recommends hospital admission for moderate- to high-risk myocarditis for monitoring and treatment (Class I, Level C), and invasive coronary angiography or coronary CT, depending on clinical likelihood, if ACS is suspected (Class I, Level C).^[1]
• ESC 2025 Table 3 calls acute myocarditis fulminant if it is of acute onset in haemodynamically unstable patients requiring inotropes or mechanical circulatory support; ESC 2025 advises referral, when needed, to tertiary centres that can institute temporary MCS and perform early EMB.^[1]

Step 2 — Supporting the circulation and the rhythm

Discussion:

• A timely and dedicated Shock Team discussion is recommended in myocarditis with haemodynamic compromise, to decide on escalation to MCS and a long-term plan (ESC 2025, Class I, Level C).^[1]
• Temporary MCS should be considered in patients with myocarditis and cardiogenic shock, or acute decompensation in chronic myocarditis, to stabilize the patients (ESC 2025, Class IIa, Level C); VA-ECMO is the most frequently applied or recommended approach.^[1]
• An IABP should be considered as first-line MCS in cardiogenic shock, with prompt escalation if haemodynamic and end-organ perfusion improvement is not seen within 1 h maximum (ESC 2025).^[1]
• Temporary transvenous external pacing should be considered in acute myocarditis with high-degree conduction disorders as a bridge to recovery (ESC 2025, Class IIa, Level C).^[1]
• The AHA 2020 fulminant myocarditis statement advises avoiding rate-control agents for sinus tachycardia, especially those with negative inotropic properties such as metoprolol, diltiazem or verapamil, because in patients with systolic dysfunction cardiac output may depend on a compensatory increase in heart rate.^[6]

Step 3 — Biopsy

Discussion:

• EMB is recommended in high-risk myocarditis and/or haemodynamic instability, and/or in intermediate-risk myocarditis not responding to conventional therapy, to detect a specific histologic subtype and assess viral genome for treatment (ESC 2025, Class I, Level C).^[1]
• Her picture also meets the ESC 2025 giant-cell row: EMB is recommended in suspected GCM due to unexplained new-onset HF of up to 2 weeks with a normal or dilated left ventricle and new ventricular arrhythmias, second- or third-degree AV block, or failure to respond to usual care within 1 to 2 weeks, to initiate specific treatment (Class I, Level C).^[1]
• EMB should be performed as soon as possible, even on temporary MCS; i.v. steroids before EMB may reduce its diagnostic yield in suspected giant-cell myocarditis (ESC 2025).^[1]
• Specialised centres should provide EMB results at least within 3 days, optimally within 8 h (ESC 2025).^[1]

Step 4 — The biopsy shows giant-cell myocarditis

Discussion:

• Combined immunosuppressive therapy is recommended in diagnosed giant-cell myocarditis (ESC 2025, Class I, Level C); corticosteroid monotherapy is not associated with longer transplant-free survival.^[1]
• ESC 2025 Table 12 first line, severe disease: i.v. methylprednisolone 7–14 mg/kg/day for 3 days, then 1 mg/kg/day p.o., plus an immunosuppressive (azathioprine or mycophenolate mofetil, cyclosporine); second line ATG, cyclophosphamide or rituximab.^[1]
• In giant-cell myocarditis, ESC 2025 reports that combining immunosuppressive therapy with corticosteroids and cyclosporine, azathioprine or both improved transplant-free survival on average to 12 months, while patients treated with corticosteroids alone survived on average 4 months.^[1]
• ESC 2025 reports that several national and international multicentre studies of patients on VA-ECMO support for fulminant myocarditis showed no freedom from heart transplantation in those with giant-cell fulminant myocarditis.^[1]

Step 5 — Arrhythmia and the ICD question

Discussion:

• GCM carries a high risk of life-threatening VA, exceeding 50% at 5 years in one single-centre study, and ICD implantation can be considered (ESC 2025).^[1]
• ESC 2025 notes that it is generally accepted to wait 3–6 months after an acute episode of myocarditis to evaluate the need for an ICD, but that early consideration of an ICD is warranted in patients presenting with symptomatic VA, or heart block in GCM or cardiac sarcoidosis.^[1]
• In the acute phase, ICD implantation may be considered for sustained VA (Class IIb, Level C), and a WCD for 3–6 months should be considered as a bridge to recovery (Class IIa, Level C) (ESC 2025).^[1]

Step 6 — Recovery and follow-up

Discussion:

• Adherence to the ESC HF guidelines is recommended for LV systolic dysfunction and/or HF (ESC 2025, Class I, Level C), and HF therapy should be considered for at least 6 months after complete LV recovery (Class IIa, Level C).^[1]
• Long-term follow-up is recommended for complicated myocarditis (ESC 2025, Class I, Level C), with CMR at least within the first 6 months (Class I, Level C).^[1]
• Stopping or reducing immunosuppression is associated with GCM recurrence as long as 8 years after diagnosis (ESC 2025).^[1]
• ESC 2025 recommends restriction of physical exercise until remission, for at least 1 month, in athletes and non-athletes after IMPS, using an individualized approach (Class I, Level C); separately, it says follow-up should be prolonged and lifelong in complicated cases or with residuals.^[1]