The aim of the mCAV study is a comprehensive characterization of the genetic, morphological and functional phenotype of isolated microvascular graft vasculopathy (mCAV) after orthotopic heart transplantation (OHT).

The utilized methods include dynamic echocardiography, magnetic resonance imaging, invasive microvascular resistance measurements, histology, cellular calcium-signaling and magnetocardiography as well as molecular genetic expression analysis (miRNA based).

Inclusion Criteria:

• able to consent
• Written consent of the participant after clarification and sufficient time to think about participation
• heart transplant recipient
• Indication for routine invasive diagnostics or due to symptoms
• Exercise tolerant in everyday life - cycling, climbing stairs at least 2 floors at a moderate speed without symptoms of exertion or dyspnea

Exclusion Criteria:

• Addiction or other diseases that do not allow the patient to assess the nature and scope as well as possible consequences of the study
• Patients or their legal guardians who do not sign the declaration of consent or who cannot fully understand it due to a lack of German language skills
• Pregnant women, breastfeeding women
• Severe comorbidities affecting the miRNA profile: diabetes mellitus, malignancy, end-stage renal disease with renal replacement therapy
• Contraindication to the stress test: signs of cardiac decompensation, angina pectoris, dyspnea, hyperthyroidism, GFR <30 ml/min, peripheral arterial disease, pheochromocytoma, angle-closure glaucoma, prostate adenoma, paroxysmal tachycardia, tachycardia atrial fibrillation
• Evidence of an acute rejection or local wall motion disturbances in the resting echocardiography

Heart transplant recipients