Purpose Cardiovascular involvement is common in patients with systemic lupus erythematosus (SLE) and changes in heart rhythm are frequent in addition to the manifestations included in the classification criteria (2019 ACR/EULAR). QTc-interval prolongation is a risk factors for serious adverse events and sudden cardiac death. Previous studies have identified specific therapy (e.g. hydroxychloroquine) and anti-Ro/SSA antibodies as risk factors.1 The aim of our study is to estimate the prevalence of QTc prolongation in a monocentric cohort and to evaluate possible correlation with autoantibodies and therapies.
Methods An electrocardiographic study (ECG) was proposed to patients affected by SLE consecutively attending our Lupus Clinic from November 2021 to March 2022. All subjects were tested for anti-Ro/SSA antibodies. Exclusion criteria were: severe valvulopathies, hypertrophic or dilated cardiomyopathy, previous pacemaker or implantable cardioverter-defibrillators implants. QTc measurement was calculated using the Bazett’s formula and prolongation was defined according to American Heart Association/American college of Cardiology recommendations (QTc>470 ms for males, QTc>480 ms for females).2 Quantitative variables were compared with T-test.
Results From November 2021 to March 2022, 120/137 (87.56%) patients with SLE consecutively seen in the clinic, accepted to undergo an ECG : 109 females (90.8%), 11 (9.2%) males; 106 (88.3%) Caucasians (median age 53.2 [IQR 42.3–58.7], median disease duration 20.0 years [12.0–28.2]). Fifty-four (45%) patients were positive for anti-Ro/SSA antibodies. Median QTc was 408.4 [IQR 389.1–428.3] ms and only 2/120 (1.7%) had a prolonged QTc (one female anti-Ro/SSA negative and one female anti-Ro/SSA positive with respectively a QTc of 488 ms and 492 ms). Comparing QTc of anti-Ro/SSA positive patients to those of anti-Ro/SSA negative patients no statistical difference was observed (409.0 [390.1–427.2] ms vs 407.0 [389.2–430.4] ms; p=0,7907). Various other electrocardiographic alterations were found: 3 (2.5%) 1st degree atrioventricular block, 15 (12.5%) bundle branch blocks BBB (13 right BBB and 2 left BBB), 32 (26.7%) repolarization anomalies, 1 (1.0%) Wolff Parkinson White; none of these patients had a QTc prolongation.
Conclusions The preliminary results of this study show a lower prevalence of QTc prolongation compared to previous studies with no differences between anti-Ro/SSA positive and anti-Ro/SSA negative patients. Further details will be available with data from 24hours ECG and a better characterization of anti-Ro/SSA antibodies (isotypes and titers).
Lazzerini, et al, Journal of the American Heart Association, 2021
Drew BJ, et Al. Circulation, 2010
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