Ventricular fibrillation waveform characteristics in out-of-hospital cardiac arrest and cardiovascular medication use

BACKGROUND: Ventricular fibrillation (VF) waveform analyses are considered a reliable proxy for OHCA characteristics in out-of-hospital cardiac arrest (OHCA), but patient characteristics such as cardiovascular medication use might also be associated with changes in VF waveform measures. OBJECTIVES: To assess associations between cardiovascular medication use and amplitude spectrum area (AMSA) of VF, while correcting for the presence of cardiovascular disease (CVD), CVD risk factors, and OHCA characteristics. METHODS: We included 990 VF patients from an OHCA registry in the Netherlands, with available information on medical history and cardiovascular medication use. Associations between cardiovascular medication use and AMSA were tested in a multivariate linear regression model, adjusting for CVD, CVD risk factors, and OHCA characteristics. Model performance was shown using R-square and R-change. We also calculated whether medication use was associated with faster dissolution of AMSA to lower values with increasing time delay. RESULTS: In the multivariate analysis, when corrected for CVD, CVD risk factors and OHCA characteristics, only potassium-sparing agents were associated with a lower AMSA when compared to patients using other cardiovascular medications (OR 0.46 [95% CI 0.10-0.81]; P < 0.012). The decrease in AMSA with increasing EMS-call-to-ECG delay was the same for patients with and without cardiovascular medication use (all P > 0.05). Only a small part of the variance in AMSA could be explained by medication use (R-square 0.003- 0.026). Adding OHCA characteristics to the model resulted in the largest R square change (0.09-0.15). CONCLUSIONS: It is unlikely that there is a strong and clinically relevant independent pharmacologic effect of cardiovascular medication use on AMSA. In OHCA, AMSA might be used as patient management tool without considering cardiovascular medication use.