I recently came across a very important blog post on the use of the novel new blood-thinner, dabigatran (Pradaxa).

Fellow Kentucky cardiologist, and frequent TheHeart.org contributor, Dr. Melissa Walton-Shirley wrote this very detailed case presentation involving a cantankerous non-compliant rural patient with AF (atrial fibrillation) that sustained a stroke while “taking” dabigatran.

Dr. Walton-Shirley details the very commonly done procedure of cardioversion (shock) for AF. As she clearly points out, the most important safety feature of shocking AF back to regular rhythm entails adequate blood thinning before and after the procedure. Thin blood prevents the possibility of clots dislodging after restoring normal contraction to the top chambers of the heart (atria).

Herein lies the rub with dabigatran, and the two soon-to-be-approved non-warfarin blood-thinning agents, apixaban and rivaroxaban. In the past, with warfarin, the doctor was responsible for confirming a patient’s compliance. This task was easy on the doctor: patients come in for weekly INRs before and after the shock. If an inadequate INR was found, the procedure was postponed. Responsibility was squarely on the doctor.

But the irony of the new blood-thinning drugs is that their most attractive feature, convenience of not needing frequent blood tests, shifts the burden of responsibility to the patient. Because these new blood-thinners do not reliably affect any measurable blood tests, the doctor cannot know whether the patient has had an adequate period of blood thinning before (or after) shocking the AF back to rhythm. Only the patient can know. In a RE-LY sub-study, cardioversion with dabigatran was found to be safe, but these were study patients, not cantankerous patients that “a secretary had to deploy the National Guard to locate.”

In Dr. Walton-Shirley’s case, she took the patient at his word: that he was taking dabigatran before the shock. But after he suffered a stroke less than 24 hours later, both circumstantial and real evidence suggests that he was non-compliant with his regimen of dabigatran. Fortunately, the patient recovered well from his stroke, albeit with a rocky course.

Dr. Walton-Shirley goes on to dissect the case. She writes about three lessons that could be learned in this case. It’s an important discussion.

Role of TEE (trans-esophageal echo) before the case:

She mentions the possibility of searching for a clot inside the heart by doing a TEE before the shock. The problem here is that doing a TEE means sedating a patient and sticking a very large rigid black tube into the esophagus. This far from non-invasive procedure is not needed in patients who have adequate blood thinning before the shock. In her case, the patient ended up with a severe complication from a TEE at an outside institution. She rightly concludes that TEEs are not the answer to confirming patient compliance.

Role of measuring the PTT (a common measure of blood-thinning) pre-shock:

Though it is true that patients that have taken dabigatran the day before the procedure have elevated PTTs, it does not in anyway confirm that the patient was taking the drug for the prior 3 weeks. Nor does it imply the patient will take the drug after the shock, which is of equal significance.

The general concept of using dabigatran in patients non-compliant with warfarin:

After this case, Dr. Walton-Shirley writes, “I will never utilize dabigatran in a patient with a history of poor or marginal compliance, because even if their PTT is adequate at the time of cardioversion, there is no guarantee they will be taking it regularly in the future or that they’ve been compliant with it consistently.”
Few could disagree with that statement.

I commend Dr. Walton-Shirley for writing such an important case report.

My comments on the case are as follows:

The new paradigm that these novel blood-thinning drugs have created represents a seismic shift for doctors and patients. For doctors, we have to decide, no, call it judge, perhaps even trust, that our patients will comply with taking an expensive drug that makes them feel no differently.

Doctors vary in the degree that they mother patients. Some will send the National Guard to locate a patient to get them into the office for their care, while others are of the ilk that think a patient needs to accept at least enough responsibility to get to the doctor’s office for routine care. They take the view, if a person can afford 12$ per day for cigarettes, they can afford a ride to clinic. This notion of mothering will have a lot to do with how a doctor uses these new drugs. Do they want the responsibility (of confirming INRs), or is it okay for the patient to be responsible (for taking the drug as directed)?

Ultimately, preventing strokes with potent drugs that patients must take as directed, and doctors cannot confirm that they have done so, highlight three important criteria for good outcomes with any medical treatment:

• The critical role of patient responsibility for their own health. Non-warfarin blood thinners place the onus on the patient. The conveniences of these drugs come with a hefty price: personal accountability.
• The ever-important communication skills of the doctor in explaining the concepts of these novel drugs.
• The requirement that doctors exercise sound judgment in deciding whether a patients can garner benefits from this very new paradigm of therapy.

It’s an exciting time to be an AF doctor.

Thanks to Dr. Walton-Shirley for sharing such an important case.

JMM