Inclusion Criteria:

1. Adult patients (age ≥ 18 years)

2. Symptom onset < 24h

3. With a high probability of TTS:

   1. InterTAK Diagnostic Score > 39 and
   2. Regional wall motion abnormality (WMA) consistent with TTS; no coronary intervention (PCI), or reperfused myocardial ischemia according to MRI

4. With a high probability of impaired outcome:

   1. InterTAK Prognostic Score >15 or
   2. GEIST Score > 19

Exclusion Criteria:

1. Suspected infection
2. Cardiac arrest, ventricular fibrillation, invasive ventilatory support
3. Known hypersensitivity to CsA, egg, peanut, or soya-bean proteins
4. Renal insufficiency (creatinin clearance < 30 ml/min/1.73m²)
5. Liver insufficiency
6. Uncontrolled hypertension (>180/110 mmHg)
7. Hypericum perforatum, Stiripentol, Aliskiren, Bosentan, or Rosuvastatin treatment
8. Pregnancy or women of childbearing age without contraception
9. Any disorder associated with immunological dysfunction < 6 months prior to presentation
10. Immunosuppressive therapy
11. Participation in another clinical trial