The purpose of this study was to determine the extent of agreement between adherence measures obtained using two technological interventions, electronic monitoring (EM) and a smartphone application (App). Clinicians, patients, and researchers depend on valid measurements of medication adherence to inform the delivery of preemptive care when needed. Technology is routinely used for monitoring medication adherence in both clinical practice and research, yet there is a dearth of research comparing novel App based approaches to traditional approaches used for assessing medication adherence. Adherence rates were captured on both the EM and the App for 3697 daily observations from 44 participants with acute coronary syndrome over 90 days immediately following discharge from acute care. For EM, adherence was measured using EM equipped pill bottles. For the App, adherence was measured by having participants upload daily photos to the App prior to taking their daily aspirin. Agreement was assessed using a Bland-Altman analysis. The mean adherence rate was higher on the App, 92%, than the EM, 78% (p < 0.001). The mean difference in adherence rates between these methods was 14% (95% Confidence Interval: −23%, −5%). These findings illustrate a lack of agreement between technological interventions used for measuring adherence in cardiovascular patient populations, with higher adherence rates observed with the App compared to EM. These findings are salient given the increased reliance on telehealth due to the ongoing COVID-19 pandemic. •Valid measurements of medication adherence are needed to inform the delivery of preemptive care.•Few studies have compared novel App based approaches to traditional approaches to assess medication adherence.•The mean adherence rate was higher on the App (92%) than the electronic monitoring (EM) device (78%) (p < 0.001).•The 14% difference suggests the App is an accurate method for measuring medication adherence and potentially better than EM.