Cumulative dose of hydroxychloroquine is associated with a decrease of resting heart rate in patients with systemic lupus erythematosus: a pilot study.
INTRODUCTION
The use of hydroxychloroquine (HCQ) in patients with systemic lupus erythematosus (SLE) offers a wide range of benefits. However, there are evidence in favour of cardiotoxicity, including heart conduction disturbances and congestive heart failure.


OBJECTIVE
To determine the effects of HCQ in the resting heart rate (RHR) of SLE patients.


PATIENTS AND METHODS
Included were patients with non active SLE, with a sedentary lifestyle and treated with HCQ. Excluded were patients on beta blocker treatment, trained patients, pacemaker's users and patients with clinical or analytical evidence of anemia, renal disease, obstructive pulmonary disease, obesity, uncontrolled thyroid disease, fever or current infection. Standard 12-lead electrocardiogram was performed in the resting condition (supine decubitus and orthostatic position). Comparison between groups was performed using Mann-Whitney U test. A multiple linear regression was performed. A p value <0.05 was considered statistically significant.


RESULTS
42 patients were included. Patients were divided in two groups based on the cumulative dose of HCQ (CD-HCQ), considering 365 g as cut-off. There were 24 patients with low-HCQ (<365 g) and 18 patients with high-HCQ (>365 g). Non significant differences were found in age, sex, prednisone dose or SLEDAI. The mean RHR was 73 ± 6 beats/min in the low-HCQ and 65 ± 7 beats/min in the high-HCQ, with a significant decrease of 11% (p = 0.003). In multiple linear regressions, there were non significant association between the decrease of RHR and prednisone dose, age, SLEDAI or TSH, but there was significant association between RHR and CD-HCQ (p = 0.024) and RHR and time of exposure to HCQ (p = 0.029).


CONCLUSION
CD-HCQ higher than 365 g was associated with a significant decrease (11%) in RHR in non-active SLE patients, although a larger prospective study is required to allow more definitive conclusions.
['Cairoli|E|E|', 'Danese|N|N|', 'Teliz|M|M|', 'Bruzzone|M J|MJ|', 'Ferreira|J|J|', 'Rebella|M|M|', 'Cayota|A|A|']
D000328:Adult D000893:Anti-Inflammatory Agents D018501:Antirheumatic Agents D066126:Cardiotoxicity D004305:Dose-Response Relationship, Drug D016903:Drug Monitoring D004562:Electrocardiography D005260:Female D005500:Follow-Up Studies D006339:Heart Rate D006801:Humans D006886:Hydroxychloroquine D008180:Lupus Erythematosus, Systemic D008297:Male D008875:Middle Aged D015999:Multivariate Analysis D010865:Pilot Projects D011241:Prednisone D011446:Prospective Studies D016896:Treatment Outcome
hydroxychloroquine heart rate Systemic lupus erythematosus