The diagnosis of long QT syndrome (LQTS) in the fetus is rare and can be difficult to manage. Fetuses most commonly present with sinus bradycardia but can develop more significant arrhythmias such as pseudo-atrioventricular block and ventricular tachycardia. Here we report the case of a fetus presenting with "pulseless" ventricular tachycardia in the setting of LQTS, including diagnostic strategies as well as fetal and postnatal management.

Immune checkpoint inhibitors (ICIs) can cause serious toxicities due to widespread immune activation. We report the case of a 49-year-old man with lung cancer who presented with confusion and seizures 16 days after receiving atezolizumab. Investigations were unrevealing of a cause. Immunotherapy-related encephalitis was suspected, given the temporal association between symptoms and atezolizumab infusion. Despite treatment with antimicrobials and methylprednisolone, the patient developed ventricular standstill requiring cardiac pacing. Although neurology and cardiac rhythm improved with high-dose methylprednisolone and pacemaker insertion, the patient developed hepatitis and acute kidney injury (AKI) during steroid tapering, which resolved with re-escalation. This case highlights a potential life-threatening multiorgan dysfunction that can complicate ICI therapy. While established toxicity phenotypes present with synchronous multiorgan involvement, atypical cases may present with sequential organ involvement that can pose significant diagnostic challenges. This reinforces the need for vigilance and early multidisciplinary team coordination to ensure timely diagnosis and good outcomes.

Immune checkpoint inhibitors (ICIs) have improved outcomes in advanced hepatocellular carcinoma (HCC), but severe multisystem immune-related adverse events (irAEs) remain a major clinical challenge. We report an autopsy-confirmed case of advanced HCC treated with tremelimumab plus durvalumab that developed severe metachronous multisystem irAEs characterized by sequential pancreatitis, laryngeal edema with sialadenitis, and myocarditis. Twelve days after treatment initiation, the patient presented with fever and abdominal distension, and computed tomography showed CTCAE grade 3 pancreatitis. On hospital day 6, he developed life-threatening laryngeal edema requiring intubation and steroid pulse therapy. Although the airway edema improved, complete atrioventricular block developed on day 23. Cardiac troponin I increased to 42,006 pg/mL, and endomyocardial biopsy demonstrated CD8-predominant myocarditis consistent with CTCAE grade 4 irAE. Cardiac conduction recovered after additional corticosteroid therapy, but the patient subsequently died of septic shock. Autopsy revealed CD8-positive lymphocytic infiltration not only in clinically recognized irAE-affected organs, including the pancreas, salivary glands, pharynx/larynx, and heart, but also in clinically silent organs, including the kidneys and intestine, indicating widespread subclinical immune-mediated injury. Multiplex immunofluorescence analysis demonstrated CD3-positive T-cell infiltration enriched for CD8-positive T cells, with variable or focal Granzyme B expression across affected tissues. In contrast, CD68-positive macrophages and CD66b-positive neutrophils were not the dominant inflammatory populations. This clinicopathological autopsy case supports the concept that clinically apparent irAEs may represent only the visible portion of systemic CD8-positive T-cell-dominant immune-mediated injury. Severe irAEs after tremelimumab plus durvalumab therapy may progress metachronously and involve clinically silent organs beyond those recognized during life, highlighting the need for continued multisystem monitoring after the onset of severe irAEs.

Cardiac involvement in rheumatoid arthritis (RA) is uncommon and often clinically silent, but may encompass valvular, structural, and conduction system abnormalities. Involvement of the mitral-aortic intervalvular fibrosa (MAIVF) and the membranous interventricular septum is exceptionally rare and has not been previously described in RA. A 61-year-old man with longstanding seropositive RA presented with syncope due to intermittent complete atrioventricular block. Multimodality imaging revealed severe degenerative mitral regurgitation, moderate-to-severe aortic regurgitation, a pseudoaneurysm of the MAIVF extending into the left ventricular outflow tract, and a membranous interventricular septal aneurysm. Infective and congenital etiologies were excluded by repeated negative blood cultures, 18F-FDG PET, and comprehensive imaging. The patient underwent successful surgical mitral and aortic valve replacement. Histopathological analysis demonstrated rheumatoid nodules within both excised valves, confirming immune-mediated valvular involvement. Persistent conduction abnormalities required permanent pacemaker implantation. This report describes the first documented case of a MAIVF pseudoaneurysm in a patient with RA, associated with multivalvular disease and high-grade conduction disturbance. The findings highlight the potential for severe, atypical cardiac manifestations of RA in the absence of active systemic inflammation and underscore the pivotal role of multimodality imaging and multidisciplinary evaluation in establishing diagnosis and guiding management.

Persistent left superior vena cava (PLSVC) can complicate transvenous device implantation due to challenging venous anatomy and limited sheath support during physiologic pacing lead delivery.

Congenital complete atrioventricular block (CCAVB) is a well-recognized manifestation of neonatal lupus erythematosus (NLE), caused by transplacental transfer of maternal anti-Ro/Sjögren's Syndrome Type A (SSA) and anti-La/Sjögren's Syndrome Type B (SSB) antibodies. Although non-cardiac manifestations of NLE typically resolve within the first year of life, the long-term autoimmune risk in affected offspring remains unclear. We report a 24-year-old woman with CCAVB secondary to maternal Sjögren's disease who presented with acute heart failure, nephrotic-range proteinuria, bicytopenia, pericardial effusion, and findings concerning for Libman-Sacks endocarditis. Despite negative conventional lupus serologies, renal biopsy demonstrated Class IV/V lupus-like immune-complex glomerulonephritis with full-house immune complex deposition, leading the multidisciplinary team to favor seronegative lupus nephritis. This case demonstrates the diagnostic limitations of serology-based approaches in atypical lupus presentations and underscores the critical role of tissue biopsy. The case also raises questions regarding long-term autoimmune risk after autoimmune congenital heart block, an area for which prospective data and evidence-based surveillance strategies remain limited.