CARDIAC CONDUCTION IN THE KEARNS-SAYRE SYNDROME (A NEUROMUSCULAR DISORDER ASSOCIATED WITH PROGRESSIVE EXTERNAL OPHTHALMOPLEGIA AND PIGMENTARY RETINOPATHY) - REPORT OF 2 CASES AND REVIEW OF 17 PUBLISHED CASES

Data were collected on 19 patients with the Kearns-Sayre syndrome, 17 described in published reports and 2 seen by the authors; this allowed a critical analysis to be made of cardiologic manifestations in this disorder. Complete heart block was present in two subjects and developed in two others while they were under observation; and Mobitz type II second degree atrioventricular (A-V) block was present in four. Sixteen patients had left anterior fascicular block alone or in combination with right bundle branch block. Four patients whose surface electrocardiogram revealed bifascicular block had a His bundle electrogram revealing trifascicular disease. Two patients had a short P-R interval, and two more had enhanced A-V conduction (short A-H intervals) on His bundle electrography. The observations indicate that in the Kearns-Sayre syndrome the myocardium is largely or completely unaffected while the conduction system is selectively involved. Two seemingly contradictory alterations in cardiac conduction appear to coexist, namely, progressive impairment of infranodal conduction and increased velocity of A-V nodal conduction. Reentrant supraventricular tachycardia may be related to abnormal conduction characteristics of the A-V node. The small incidence of P-R interval prolongation apparently reflects a reciprocal interplay between enhanced A-V nodal and prolonged infranodal conduction. The lifethreatening risk is high degree infranodal heart block (accounting for three deaths in patients aged 13 to 16 years). The need for prophylactic pacemakers is underscored (six patients between 12 and 28 years were alive with a pacemaker). © 1979.