Background: Older adults often have polypharmacy and multiple comorbidities. Cardiovascular diseases (CVDs) are the most common morbidities in older adults and are linked to many adverse drug effects and drug-related issues. Several patient settings use the medication appropriateness index (MAI) to assess older adults’ Potentially Inappropriate Medication (PIM) prescribing. Aim: This study estimated CVDs outpatient clinic PIM prescribing. It also tested the MAI’s ability to detect and quantify PIMs in CVD outpatient clinics. Methods: It is a cross-sectional, single-center, cardiovascular outpatient clinic study. Demographic, medical, and drug data from 65 years or older patients were retrospectively reviewed. Two clinical pharmacists randomly selected 70 patients and assessed medication appropriateness using the MAI. Statistical Package for the Social Sciences (SPSS) descriptive and logistic regression analyses calculated the number of potentially inappropriate medications, the percentage of patients with inappropriate medication prescribing, and factors associated with inappropriate medication prescribing. Results: Total of 87.14% of participants had PIMs. Two clinical pharmacists evaluated 539 prescriptions, and 59.9% had an MAI weighted score of zero (no prescription error). Drug-drug interaction, duplication, and drug-disease interaction almost perfectly agreed among raters. The two raters’ MAI criteria kappa coefficient was 0.44, indicating moderate agreement. The results showed that only some medications significantly affected MAI-defined inappropriate prescribing. Conclusion: The MAI is a reliable and valid tool in CVD outpatient clinics. A relatively high prevalence of PIMs was found in the studied population. It mandates implementing specific measures to reduce PIMs.