It's some sort of Supraventricular Brady-Escape Rhythm. Without a clearer strip; we can't fully interpret the Rhythm... You have to look at all variables which may have caused the Artifact. Was there fine muscle movement? Were you in the Ambulance with the engine running? Was someone in the house operating an electric powered appliance? Was there ointment or gel on the skin? Was the skin dry? Did you press on the electrodes due to diaphoresis or dry/flaky skin? Have you notice the Monitor to have Artifactky isoelectric lines on other patients? Maybe it needs service...
Remember she's approaching 100y/o... If her complaint was just feeling tired and the only finding was this bradtcardia; Pharmaco-Intervention could wait until you get to the ER.... How was the rest of her presentation? Mental Status? What was her RR and BP (You said stable but stable is subjective)? SpO2? PMH and Medications (Prescribed, OTC, Herbal, Recreational)? Who let you into the house? Bystanders/family/friends; any story? So many factors to take into consideration before the bolus of 650cc NaCl... BLS intervention: when in doubt, do. ALS intervention: when in doubt, don't do, for the most part (Unless it's ECG, SpO2, ETCO2, & IV)...
I'm just saying... I wasn't there; I'm sure your Interventions were appropriate... Thank you for sharing...