Positive Regadenoson Stress Test in a Patient on Phentermine With Normal Coronaries

Obesity is a well-established cardiovascular (CV) risk factor with greater mortality and morbidity rates than the general population. Phentermine is a weight loss medication that is approved for short-term obesity treatment in conjunction with lifestyle modifications to decrease CV risk. A 51-year-old female with Raynaud’s phenomenon who was started on phentermine one week prior presented with a one-day history of palpitations. Subsequent workup revealed non-ST elevation myocardial infarction (NSTEMI) on presentation and worsening ST segment depressions following regadenoson injection during pharmacological stress testing. Although current evidence suggests that the use of phentermine is safe and may even reduce the risk of CV disease in obese patients, it still may pose adverse CV effects. A detailed medical history, including medications used and predisposing conditions, is crucial to help identify and possibly prevent exacerbation of such CV side effects.