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A 35 year old Afro-Caribbean man was referred by the dermatology department in March 2002. He had a 2 year history of a photosensitive rash, patchy alopecia, and a 1 year history of arthralgia affecting wrists, knees, and shoulders. He also described occasional night sweats. There was no history of thromboembolic events or migraine.
On examination he had two patches of alopecia and a small right knee effusion. His pulse was 64 beats per minute and regular, with a blood pressure of 120/70 and normal heart sounds. Otherwise his examination was unremarkable.
Investigations showed: positive antinuclear antibody (ANA; 1/160 homogeneous pattern); positive double stranded DNA on enzyme linked immunosorbent assay (ELISA) testing (169 IU/ml; negative <40); extractable nuclear antigen negative for Ro, La, Sm, RNP, Jo-1 antibodies; positive IgG anticardiolipin antibody (37 GPLU/ml; negative <14); normal complement C3 and low C4 (0.11 g/l; normal 0.16–0.47); normal full blood count including differential white cell count, renal and liver function, creatine kinase, erythrocyte sedimentation rate, and C reactive protein. His lupus anticoagulant test was also positive on two occasions. A diagnosis of systemic lupus erythematosus (SLE) was made.
Five years previously he had been investigated by the cardiologists for episodes of chest pain and dyspnoea. An initial ECG showed first degree heart block. A 24 hour ECG showed sinus rhythm with first degree heart block throughout, but also significant degrees of second degree heart block, and episodes of third degree block occurring at night with a maximum pause of 3.02 seconds. As he had no syncopal symptoms no further action was taken.
There was a family history of SLE in his mother, who had positive ANA and positive Ro and La antibodies.
Conduction defects in SLE are well described: congenital heart block in infants born to mothers with anti-Ro antibodies is the most widely known. These infants do not seem to have a greater risk of developing adult SLE than that conferred by maternal family history. Conduction disturbances in adults with SLE are rare but documented, in the form of all types of atrioventricular (AV) block, bundle branch block, sinus tachycardia, atrial fibrillation, and atrial ectopic beats.1 The prevalence of conduction defects may be as high as 10–14%.1,2 Third degree block is very rare in adults with SLE—this is only the 11th case described.3 The pathology is thought to be nodal artery occlusive lesions with secondary collagen degeneration and fibrosis of AV and SA nodes.4–6
One study shows that anti-Ro antibody positive adults with SLE are more likely to have conduction defects than anti-Ro negative patients.7 This may provide a clue to the pathophysiology as anti-Ro antibodies are thought to be pathogenic in fetal heart block. However, other authors found conduction defects in only two of 33 patients with SLE, neither of whom was positive for Ro or La. The 12 patients with Ro or La antibodies, or both, did not have conduction problems.8 Although the detection of the antibodies was by differing techniques, overall the pathogenesis does not appear to be related to the presence of Ro or La antibodies.
In the case we describe, possible mechanisms are (a) varying degrees of intermittent heart block since birth and related to maternal Ro positivity; (b) nodal artery occlusive disease secondary to vasculitis; (c) idiopathic fibrosis; and least likely in view of his age, (d) ischaemic heart disease.
This is the first description of high grade heart block predating the diagnosis of SLE. The occurrence of high grade heart block in young adults could prompt a search for other symptoms, signs, or laboratory tests of SLE.