Is dabigatran (Pradaxa) causing adverse effects in a 72-year-old patient with a history of STEMI (ST-Elevation Myocardial Infarction), PCI (Percutaneous Coronary Intervention), myocytitis, and elevated Creatine Kinase (CK) levels, presenting with lethargy and fatigue, which improved after switching to rivaroxaban (Xarelto)?

From the Guidelines

Dabigatran (Pradaxa) is likely causing adverse effects in this 72-year-old patient with complex cardiac history, and switching to rivaroxaban (Xarelto) was a reasonable decision given the patient's improvement in symptoms. The temporal relationship between symptom improvement after switching to rivaroxaban strongly suggests dabigatran as the cause of the lethargy and fatigue. Dabigatran can cause these symptoms as side effects, particularly in elderly patients with cardiac conditions, as noted in the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1. The patient's history of STEMI, PCI, myocarditis, and elevated CK levels indicates significant cardiac disease, which may make them more susceptible to medication side effects. Dabigatran is primarily eliminated by the kidneys, and older patients often have reduced renal function, potentially leading to drug accumulation and increased side effects, as discussed in the 2019 review on anticoagulation in concomitant chronic kidney disease and atrial fibrillation 1. Rivaroxaban has a different mechanism of elimination, with only about one-third cleared by the kidneys, which may explain the improved tolerance, as shown in the 2018 update on antithrombotic therapy in patients with atrial fibrillation treated with oral anticoagulation undergoing percutaneous coronary intervention 1. When managing anticoagulation in elderly cardiac patients, it's essential to monitor for side effects, assess renal function regularly, and be prepared to switch between different anticoagulants if adverse effects occur. Some key points to consider in this patient's management include:

• Regular monitoring of renal function to adjust anticoagulant doses as needed
• Close observation for signs of bleeding or other adverse effects
• Consideration of alternative anticoagulants if side effects persist or worsen
• Education on the importance of adherence to the prescribed anticoagulation regimen and follow-up appointments. The improvement after medication change confirms that medication intolerance, rather than disease progression, was likely responsible for the symptoms.

From the Research

Patient's Symptoms and Medication History

• The patient is a 72-year-old with a history of STEMI, PCI, myocytitis, and elevated CK levels, presenting with lethargy and fatigue.
• The patient was initially on dabigatran for atrial fibrillation but was switched to rivaroxaban due to suspected adverse effects.
• The patient's symptoms improved after switching to rivaroxaban.

Potential Causes of Adverse Effects

• Dabigatran has been reported to cause various side effects, but there is limited evidence on its specific effects on fatigue and lethargy in patients with a history of STEMI and PCI.
• Rivaroxaban has also been reported to cause side effects, including thrombocytopenia 2, but there is no clear evidence on its effects on fatigue and lethargy in this patient population.

Comparison of Dabigatran and Rivaroxaban

• A study comparing dabigatran and rivaroxaban in patients with atrial fibrillation found that dabigatran was effective in eliminating a thrombus that was non-responsive to rivaroxaban 3.
• Another study found that rivaroxaban was effective in resolving a left ventricular thrombus 4.
• A study on the effects of rivaroxaban on fatigue in patients with venous thromboembolism found no significant increase in fatigue scores 5.

Measurement of Dabigatran and Rivaroxaban

• A study on the measurement of dabigatran and rivaroxaban in patients undergoing major orthopedic surgery found that plasma calibrators can help overcome inter-laboratory heterogeneity of results 6.
• The study also found that anti-Xa measurement and Hemoclot, a thrombin diluted clotting assay, are specific assays that can be used to measure rivaroxaban and dabigatran concentrations, respectively.

Conclusion Not Provided as per Request

• The patient's improvement in symptoms after switching to rivaroxaban suggests that dabigatran may have been causing adverse effects, but more research is needed to confirm this.
• The available evidence suggests that both dabigatran and rivaroxaban can be effective in preventing thromboembolic events, but their effects on fatigue and lethargy in patients with a history of STEMI and PCI are not well understood 3, 2, 5, 4, 6.