Anticoagulants

[Bucko911]

Folks;


I am planning to be on a liveaboard in Thailand in about 3 1/2 weeks. This past weekend I had a case of Atrial Fibrillation. I was essentially asymptomatic, except for the fluttering associated with a ventricular response at about 165.


As this was a first time event with a known onset time (about 2 hours prior), I was immediately, and successfully cardioverted in the ER.


As a precaution I was given SC low molecular weight heparin, followed by a prescription for 1 month of Dabigatran.


I am familiar with the risks of anticoagulation and diving (essentially trauma related risk), as well as the embolization risks associated with my brief stint in AF. Given the fact that I was only in AF for a couple of hours, was successfully treated, have no symptoms 36 hours later, I am considering not completing my run of anticoagulant therapy.


I know the correct answer is to discuss this with my physician, which I will do. What I am looking for here are opinions....

 

[Dive-aholic]

Spontaneous onset of Afib. I'd stick with the anticoagulant therapy. If you go into Afib again the risks of not being on the heparin are potentially much worse.

 

[Agility]

I would be more concerned about a reocurrence of a heart rate of 165/min on a livaboard without treatment available.
This would result in a low cardiac output with higher myocardial oxygen consumption.
Ask a dive-medic.

 

[TSandM]

The risk of stroke from atrial fibrillation ranges from 1.5% to 5% per year. The higher end is patients with prior stroke symptoms, or very elderly (80's).

Anticoagulants are often prescribed for younger patients with episodic Afib, on the theory that the rhythm may recur, stroke in young patients can be a disaster, and the risks of anticoagulation are typically low. Risk of recurrence is higher in patients with structural heart disease (did you have an echocardiogram done?). Risk is lower if there is an identifiable inciting factor that can be avoided in the future (high caffeine intake, amphetamine use).

I would assume that, in addition to starting anticoagulants, they put you on some agent to do rate control should the Afib recur. What you don't know is how well it will control rate, since you are now in sinus rhythm. If you recur in the water, with a heart rate of 165, your exercise tolerance will likely be quite low at best, and your level of consciousness may be affected at worst.

This is really bad timing. I'm fairly liberal when it comes to getting people back in the water, but if I were in your shoes, I'd be hesitant and consider snorkeling under the watchful eyes of the crew. It's not the dagibatran I'm worried about.

 

[Dr. Doug Ebersole]

This is a general statement as I have very little information on your specific case.

Atrial fibrillation can be caused by a variety of things, some of which are more likely to have recurrences than others. The major risk factors for the development of atrial fibrillation are advancing age, hypertension, and underlying cardiac disease (coronary artery disease, valvular disease, weakening of the heart muscle, etc). Other things such as hyperthyroidism, pulmonary embolism (blood clots in the lungs), etc can also result in atrial fibrillation. First of all, you should have been evaluated for these things. At a minimum, you should have had an echocardiogram -- an ultrasound of your heart -- and possibly some form of stress testing if you are at risk for coronary artery disease.

Because atrial fibrillation significantly increases a person's risk of stroke, the issue of anticoagulation always arises. In general, the risk of a serious bleeding event on oral anticoagulation is around 1% per year. The question then arises as to what an individual's risk of stroke would be should they not be anticoagulated. In cardiology, we use the CHADS VAS score to estimate this risk. This is a scoring system where the patient gets a point for the following: a history of congestive heart failure, hypertension, age > 65, diabetes mellitus, prior stroke, vascular disease, age > 75, and female gender. The point score estimates the annual stroke risk. In other words, a 66 year old woman with hypertension would have a score of 3 and approximately a 3% stroke risk per year off anticoagulation. Patients with a score of zero do not need anticoagulation. A score of one is controversial. Basically, anyone with two or more points should have longterm anticoagulation. And this recommendation is independent of whether the patient is in atrial fibrillation or back in normal sinus rhythm.

Before your trip, I would recommend you have a detailed discussion with your cardiologist regarding his opinion as to your short term and long term risk of recurrent atrial fibrillation, prophylactic therapy for rate control in case the atrial fibrillation recurs, and the issue of both short term and long term anticoagulation. If your cardiologist is not comfortable with issues of diving, contact DAN for a referral to a cardiologist in your area. As to diving, the issues are the likelihood of recurrent atrial fibrillation with a rapid pulse in a remote location where therapy may be difficult and the small increased risk of bleeding from scuba diving on anticoagulation.

Doug