OBJECTIVES: Currently, it is estimated that more than 600,000 Canadians have heart failure (HF). Existing HF prevalence estimates use hospital and, where available, primary care diagnosis. However, diagnosis databases are limited in availability and coverage. Therefore, this study intended to develop a model identifying treated Canadian HF patients using retail prescription patterns from a national database to validate, and build upon Canadian literature prevalence estimates. METHODS: A decision tree model was constructed using 675 HF diagnosed (ICD-9 428) patients and 804 randomly sampled non-HF patients within IMS Health Brogan’s (IMS) E360 Canadian electronic medical record database. All patients were aged ≥18, had ≥2 doctor visits between January 2006 - January 2015, and had an ATC-1 cardiovascular prescription. The model’s CHF predictive accuracy was validated using a test dataset.  Afterward, clinical opinion was engaged to confirm the rules generated by the statistical model. We applied the model to IMS’s patient-level longitudinal prescription database to identify the prevalence of treated HF patients by age group. RESULTS: Age and standardized duration treated with a beta-blocker, ACE/ARB, high-ceiling diuretic, and vasodilator were strong predictors of HF, while physician referral and gender were not.  The model had an 80.0% accuracy, 81.1% positive predictive value, and 79.5% negative predictive value on a test dataset. The study estimated a 2014 national ≥18 aged HF prevalence of 2.31%, or 657,902 patients, which aligned well with literature estimates, 590,416 and 626,199 patients. When the model’s prevalence estimates were stratified by patient age group, the majority differed by <0.5% from literature prevalence estimates. CONCLUSIONS: The model’s HF prevalence estimates closely match the literature both in overall and age stratified prevalence. As of 2014, approximately 2.31% of Canadians aged ≥18 are treated for HF. Overall, this study provides a mechanism to calculate detailed prevalence estimates in Canada using retail prescription data.