Background/Purpose: Decreased heart rate variability (HRV) reflects autonomic dysfunction and inflammatory dysregulation and has been observed in SLE. We examined associations of HRV with clinical improvement and flare in patients with SLE participating in a clinical trial.

Methods: HRV was evaluated by a 5 minute electrocardiogram in SLE patients completing ≥2 visits in an ongoing investigator-initiated clinical trial of a targeted biologic. HRV parameters were calculated in the time (RMSSD, SDNN, pNN50) and frequency domains [high frequency (HF), low frequency (LF) and the LF/HF ratio]. Mixed effects linear models (adjusted for baseline HRV) with generalized estimating equations were used to compare changes in HRV between paired visits.

Results: Fifty-eight patients (age 46±11, 55 female) were followed in 505 consecutive visit pairs with complete data on HRV and disease activity available. Categorical improvement (≥1 letter grade improvement in BILAG A/B scores and no new BILAG A/B) occurred in 96 (19%) visit pairs and no improvement or worsening in 409 (81%). RMSSD, pNN50 and HF increased in improving vs. non-improving visit pairs [group differences: 26.1±13.3 (p=0.05), 3.9±1.8 (p=0.038) and 16.9±4.2 (p<0.0001), respectively] and the LF/HF ratio decreased (group difference: -2.1±1.0, p=0.032), suggesting a favorable change in sympathovagal balance (Table 1). There were 82 mild and 43 moderate/severe flares, assessed by a modification of the SELENA-SLEDAI flare index (mSFI) that excludes medication criteria and differentiates mild from moderate flares by physician’s global opinion (1). RMSSD, SDNN, pNN50 and HF decreased [group differences: -37.8±2.5 (p<0.0001), -63.4±31.8 (p=0.04), -10.8±2.1 (p<0.0001) and -69.1±1.8 (p<0.0001), respectively] and LH and LF/HF increased [group differences: 17.6±6.5 (p=0.007) and 5.3±1.9 (p=0.008)] in flaring compared to non-flaring visit pairs (Table 2). Moreover, SDNN, HF and LF/HF deteriorated [group differences: -23.8±5.1 (p<0.0001), -58.9±6.1 (p<0.0001) and 2.8±0.9, (p=0.002), respectively] in moderate/severe compared to mild mSFI flares.

Table 1. Average per visit changes in HRV in improving vs non-improving visit pairs.

Table 2. Average per visit changes in HRV in flaring vs non-flaring visit pairs.

Conclusion: Changes in HRV reflecting improved autonomic function correlate with clinical improvement and absence of flare in SLE. These data suggest that HRV may be a simple non-invasive tool to gage transitions of SLE disease activity. The role of HRV parameters as targets for SLE therapy warrants further investigation.

References: 1. Thanou A, et al. Rheumatology 2014;53:2175-81.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/changes-in-heart-rate-variability-reflect-clinical-improvement-and-flare-in-systemic-lupus-erythematosus/