Background/Purpose: Resting Sinus Tachycardia (ST) is found in approximately 50 % of patients with SLE. Unexplained episodes of intermittent ST could be a manifestation of disease activity. Approximately 13-15 % of patients, however, continue to have unexplained ST that persists beyond the duration of disease flare. The significance of this finding is still under investigation, but may be associated with physical deconditioning, higher SLEDAI scores or occult serositis. We conducted a retrospective study to further elucidate its clinical significance.

Methods: SLE was defined as patients fulfilling SLICC 2012 criteria. Persistent ST was defined as unexplained resting heart rate > 90 bpm in > 50 % of all outpatient visits; a minimum of 8 outpatient visits were required such that transient episodes of tachycardia were excluded. Also excluded were tachycardia episodes with potential explanation e.g. acute illness, severe pain, fever, acute anemia, hyperthyroidism, pregnancy and history of cardiac arrhythmias. A retrospective chart review was performed in patients with a diagnosis of SLE between January 2000 and December 2015. Patients meeting SLICC 2012 criteria and > 8 outpatient visits were dichotomized into groups with or without persistent ST. Multiple variables were compared: demographics; individual components of SLICC 2012 criteria at the first and the latest follow-up; laboratory tests including ENA, APL, ESR/CRP, anemia and nephritis class; pulmonary, cardiac and renal components of SLICC damage index; comorbidities including APS, hypertension, hyperlipidemia and history of deep vein thrombosis; and, hydroxychloroquine, angiotensin converting enzyme inhibitor and beta blocker use. Fisher’s exact test was used and two sided p value < 0.05 considered significant.

Results:  Charts of 375 patients were reviewed. 106 met inclusion criteria. 17 (16%) had persistent ST. At the time of statistical analysis, complete data was available in 16 patients with persistent ST and 61 patients without. The mean duration of follow up was 6.4 and 7.3 years respectively. Persistent ST was found to be associated with the following in univariate analysis: serositis at presentation (44% vs 14% P 0.017), proteinuria > 500 mg/24 hour at the latest follow up (63% vs 33% P 0.044) and anti-histone antibodies (75% vs 42% P 0.026). Quantitative analysis of maximal proteinuria revealed an association of persistent ST with any proteinuria > 500 mg/24 hr (63% vs 31% P 0.02) as well as nephrotic proteinuria > 3 gm/24 hr (44% vs 18% P 0.045). In addition, class 5 nephritis was more common (25% vs 5% P 0.031) in this group. Other variables trending towards significance include: active urinary sediment/> 5 RBCs/hpf at latest follow up (50% vs 23% P 0.059), anti-DNA antibodies (75% vs 46% P 0.0504) and APS (25% vs 8% P 0.08).

Conclusion: Unexplained persistent ST could be a meaningful clinical sign in SLE. Early in natural history, this may imply the presence of incipient serositis while later on, of an ongoing proteinuric renal disease. A novel finding of high prevalence of anti-histone antibodies in this subgroup needs further scrutiny to discern its significance.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-implications-of-persistent-sinus-tachycardia-in-systemic-lupus-erythematous-a-retrospective-study/