Reversible complete atrioventricular block caused by aortic bicuspid valve calcification with severe aortic stenosis: a case report.

BACKGROUND: The aetiology of secondary complete atrioventricular blocks includes ischaemia, cardiac sarcoidosis, electrolyte imbalance, drug use, rheumatic fever, and infections such as Lyme disease and endocarditis. Diagnosis is important since some of these causes are reversible. Although several studies have reported on aortic valve calcification causing complete atrioventricular blocks, no study has described improvement of complete atrioventricular blocks by removal of the calcification.

CASE SUMMARY: A 42-year-old man with syncope had a Mobitz type II atrioventricular block, an alternating bundle branch block, and severe aortic stenosis. We identified a 10 s paroxysmal complete atrioventricular block with pre-syncope and performed pacemaker implantation. Electrocardiography-gated computed tomography confirmed that the calcification had reached the muscular septum. 18 F-fluorodeoxyglucose-positron emission tomography (FDG-PET) revealed significant FDG uptake with high CT value of calcification in basal interventricular septum. The calcification in the septum was removed carefully, and aortic valve replacement was performed. The atrioventricular conduction capacity improved post-surgery. During the 1-year follow-up, the patient reported dramatic improvement in exercise capacity. We also noted an improvement of <0.1% in the right ventricular pacing burden.

DISCUSSION: Complete atrioventricular blocks occur in patients with aortic stenosis accompanied by severe calcification of the aortic valve, which are visualized comprehensively by echocardiography. Electrocardiography-gated computed tomography and FDG-PET enabled detailed evaluation of the extent of calcification and pre- and post-operative tissue inflammation. Hence, we suspected that the calcification in the septum was causing complete atrioventricular block. Moreover, clinicians should recognize that aortic valve calcification with aortic stenosis can cause complete atrioventricular blocks.