3RD-DEGREE ATRIOVENTRICULAR-BLOCK IN A PATIENT UNDER CHLOROQUINE THERAPY

The first case of chronic cardiac toxicity due to an antimalarial agen t was reported in 1971 and since then several cases of heart failure, restrictive cardiomyopathy or atrioventricular block have been ascribe d to this family of drugs, We report the case of a 43-year-old woman w ho developed juvenile chronic arthritis at the age of ten, followed in adulthood by seropositive rheumatoid arthritis, In 1980 she nas put u nder chloroquine sulfate (hydroxychloroquine was not available) in a d ose of 200 mg/d (152.66 mg of chloroquine), with 10 mg/day of predniso ne. She developed myalgia and increased skin pigmentation, but disrega rded recommendations that these symptoms required discontinuation of c hloroquine therapy. She was lost to follow-up, but continued the chlor oquine therapy of her own accord, In December 1993, she developed a th ird-degree atrioventricular block with syncopes requiring implantation of a pacemaker, The rare but well-documented myopathy induced bg anti malarial agents can produce early severe lesions of the cardiac muscle , which mag have a predilection for the interventricular septum, expla ining the risk of atrioventricular block, Although histologic studies were not performed in our patient, the clinical evidence of toxicity, absence of underlying heart disease and fairly young age of the patien t pointed to chloroquine toxicity. Periodic cardiac investigations inc luding electrocardiography may be warranted in patients under antimala rial therapy.