Apical hypertrophic cardiomyopathy in transplanted hearts – a rare and heterogeneous entity

Introduction Apical hypertrophic cardiomyopathy (ApHCM) after orthotopic heart transplantation (OHT) is a very rare entity, with only 20 cases reported. The prognosis and optimal management of these patients remain uncertain. We describe five cases from a single high-volume transplant centre with highly heterogeneous clinical presentations. Methods Retrospective case series of OHT recipients diagnosed with ApHCM by transthoracic echocardiography (TTE) and/or cardiac magnetic resonance (CMR). Clinical presentation, ECG evolution, imaging phenotype and outcomes were assessed. Results Five recipients (4 women), transplanted at a mean age of 57 years, developed ApHCM between 2 months and 15 years post-OHT. The most common symptom at presentation was dyspnea; with one patient reporting exertional presyncope. Donors were reputed to have normal ECG and TTE and no history of hypertension. All recipients demonstrated a similar ECG progression: initial lateral T-wave inversions, evolving to diffuse T-wave inversions, then fulfilling left ventricular hypertrophy voltage criteria, and ultimately developing the classic deep negative T-waves. Notably, ECG abnormalities preceded changes on TTE/CMR. Four patients showed the typical "Ace of spades" morphology and/or systolic obliteration of the apical cavity on contrast TTE at diagnosis or shortly after. There was right ventricular involvement in 3 patients. At diagnosis, one patient already had an apical aneurysm (40 days post-OHT) and another depicted an akinetic apex. Two presented intracavitary gradients (19 and 40 mmHg). CMR could not be performed in 2 patients and showed diffuse but non significative fibrosis in 2 others. Paradoxically, the patient with the greatest apical wall thickness (21 mm) had the most benign course. No sudden cardiac death nor all-cause mortality occurred to date. One patient had a particularly unfavourable course: transplanted for known HCM, ApHCM was diagnosed 2.5 months post-OHT. Retrospective review of TTE showed apical obliteration on day 2 post-transplant, and mild donor LVOT gradient (17 mmHg) before transplant, both previously attributed to hyperdynamic state. Direct access to donor images was limited. Conclusion ApHCM after OHT may be under-recognized and diagnosis delayed, as left ventricular hypertrophy and T-wave inversion are frequent in the acute post-transplant period. A characteristic stepwise ECG pattern may serve as an early warning sign and should prompt contrast-enhanced TTE. Contrast imaging may also have implications for donor eligibility assessment. Although outcomes were predominantly benign in our cohort, all patients demonstrated disease progression and/or high-risk features during follow-up, raising questions regarding optimal surveillance and treatment, including beta-blockade, implantable cardiac defibrillators and, in selected cases, repeat OHT.