Cardiac Rhythm Aberrations in Subacute Sclerosing Panencephalitis: Insights From Heart Rate Variability Analysis

Subacute sclerosing panencephalitis (SSPE) is a fatal neurological disorder resulting from persistent measles virus infection within the brain. Although neurological manifestations have been well-documented, the impact of SSPE on cardiac autonomic function, assessed through heart rate variability (HRV), remains understudied.

In this prospective single-center study conducted from January 2022 to March 2023 in Southern India, 30 consecutive SSPE patients and age- and sex-matched controls underwent electrocardiogram recordings for HRV analysis. Various HRV parameters were assessed, including time-domain metrics (SD of normal-to-normal intervals, root mean square of successive differences between normal heartbeats, percentage of successive normal interbeat intervals greater than 50 msec), SD1 and SD2 for Poincaré plot analysis, and frequency-domain metrics (low frequency %, high frequency %, low frequency:high frequency ratio).

In the study, SSPE patients exhibited markedly reduced HRV. Specifically, SD of normal-to-normal intervals ( P = 0.003), percentage of successive normal interbeat intervals greater than 50 msec ( P = 0.03), and SD2 ( P = 0.0016) were significantly lower compared with controls. Frequency-domain analysis did not reveal significant distinctions. Correlation analysis demonstrated a negative relationship between percentage of successive normal interbeat intervals greater than 50 msec and SSPE severity ( r = -0.37, P = 0.042). Heart rate variability did not significantly differ between SSPE stages or with clinical variables. The interbeat interval range showed a narrower distribution in SSPE subjects.

Our study highlights the clinical relevance of HRV analysis in SSPE and autonomic dysfunction throughout the disease course underscoring its importance in SSPE. This investigation provides valuable insights into cardiac autonomic dysfunction probably because of affliction of the central autonomic networks caused by the disease process and may be a contributing factor to mortality in SSPE.