The cardiac safety of chloroquine phosphate treatment in patients with systemic lupus erythematosus: the inﬂuence on arrhythmia, heart rate variability and repolarization parameters A Wozniacka 1 *, I Cygankiewicz 2 , M Chudzik 2 , A Sysa-Je ˛drzejowska 1 and JK Wranicz 2 1 Department of Dermatology; and 2 Department of Cardiology, Medical University of Lodz, Poland Antimalarials are used to treat cutaneous and systemic lupus erythematosus (SLE). Even though cardiac damage is a rare complication, over the last decade several reports have raised the issue of cardiotoxicity associated with antimalarials. Therefore, the aim of study was to evaluate the inﬂuence of seven-month chloroquine treatment with a 250 mg daily dose on arrhythmia, conduction disturbances as well as heart rate variability and repolarization parameters assessed in 24-hour Holter monitoring. The studied group included 28 SLE patients treated with chloroquine as a monotherapy. In all the patients standard 12 leads surface ECG (50 mm) and the 24-hour ECG Holter monitoring (Oxford Medilog Excel-2) were performed before and after chloroquine phosphate treatment. All subjects presented sinus rhythm both at the enrollment and after treatment. No episodes of paroxysmal arrhythmias or conduction disturbances were reported during the study. All the patients were characterized by tendency to tachycardia, but no signiﬁcant differences in mean heart rate were found before and after chloroquine administration. Similarly, no changes in heart rate variability or repolarization parameters were observed. Lupus (2006) 15, 521–525. Key words: arrhythmias; cardiac toxicity; chloroquine treatment; heart rate variability; Holter monitoring; repolarization; systemic lupus erythematosus Lupus (2006) 15, 521–525 www.lupus-journal.com PAPER Introduction Antimalarials have been used to treat cutaneous and systemic lupus erythematosus (SLE) for decades. Currently, the two most frequently used 4-aminoquino- line antimalarial compounds are chloroquine and hydroxychloroquine. These two drugs are very similar in pharmacokinetics, 1 action 2 and metabolism, 3 but the former is more popular in Poland. Antimalarials’ side effects occur in less than 10% of patients. 4 Gastrointestinal reactions are the most common. Long term administration may cause retinopathy, blood dyscrasias, corneal deposits, encephalopathy, neuropa- thy, myopathy or impairment of auditory function. Even though cardiac damage is a rare complication, over the last decade several reports have raised the issue of cardiotoxicity associated with antimalarials. Long term treatment with antimalarial drugs was reported to lead to cardiomyopathy or to provoke conduction distur- bances. 5–12 Proarrhythmic effects were also described and were suggested to be related with inﬂuence of this group of drugs on myocardial repolarization. 13 Therefore, we aimed to evaluate the inﬂuence of chronic chloroquine treatment on arrhythmia, conduc- tion disturbances as well as heart rate variability and repolarization parameters assessed in 24-hour Holter monitoring. Material and methods The studied group included 28 patients with SLE with different activity and duration of the disease, but all treated with chloroquine as a monotherapy due to slight or moderate SLE course. Taking into consideration accumulation of anti- malarials in internal organs and skin, subjects treated © 2006 SAGE Publications 10.1191/0961203306lu2345oa *Correspondence: Anna Wozniacka, Dept. of Dermatology, Medical University of Lodz, 94-115 Lodz, Krzemieniecka 5, Poland. E-mail: wozniacka@bmp.net.pl Received 17 March 2006; accepted 12 May 2006