High-Grade Atrioventricular Block Reveals Rare Transthyretin Cardiac Amyloidosis With Unique Hemodynamics

Atrioventricular (AV) block is a common cardiac conduction disorder that is frequently encountered in clinical practice; however, the association with rare systemic conditions such as transthyretin amyloidosis (ATTR) is heavily underdiagnosed. ATTR amyloidosis is a systemic disorder characterized by the deposition of abnormal transthyretin protein fibrosis in various organs including the heart and vasculature, resulting in progressive organ dysfunction. We present a rare case of high-grade AV block unveiling ATTR cardiac amyloidosis with unusual hemodynamics, specifically severe supine hypertension with severe orthostatic hypotension. These findings posed a diagnostic challenge, underscoring the importance of a comprehensive diagnostic approach and meticulous review of medical history. Following pacemaker placement and the diagnosis of ATTR cardiac amyloidosis, our patient was started on a Tafamidis regimen.