Determining Risk in the Treatment of Brugada Syndrome
Advocate Lisa Benson shares an interview with a genetic electrophysiologist, Steven Lubitz, MD, MPH, about Brugada Syndrome, a heritable heart rhythm disorder that can lead to sudden cardiac arrest.
Dr. Lubitz’s bio on massgeneral.org says, “Dr. Lubitz graduated from the University of Michigan Medical School. He trained in internal medicine and cardiovascular disease at Mount Sinai Hospital in New York, where he also served as a Chief Medical Resident. Dr. Lubitz earned a Master of Public Health degree from the Harvard University School of Public Health. He completed his clinical electrophysiology training at the Massachusetts General Hospital.”1
He is interested in the genetics of electrophysiology because he gets to see how genetics has unlocked keys to understanding the biological mechanisms of disease. He enjoys the blending of clinical work and research. In addition to Brugada Syndrome, he focuses on arrhythmia syndromes such as atrial fibrillation, slow heart rates, supraventricular tachycardias, ventricular arrhythmias, and more.
Below is a portion of the conversation, focused on determining risk and the treatment of Brugada Syndrome.
Different levels of risk
Could you explain the different levels of risk patients have in the spectrum of Brugada Syndrome?
This has been one of the biggest clinical insights with Brugada Syndrome over the last 10 to 15 years: a couple of clinical risk factors go a long way in helping us try to figure out who are at higher or lower risk, though there are still some gray zones which we struggle with clinically.
There are basically two major questions. The first is: Have you ever had an arrhythmia that was caused by Brugada Syndrome?
We can divide that into three categories:
- If somebody has had cardiac arrest before, then they’re at very high risk for having another cardiac arrest in the future.
- If somebody has had a fainting episode, and when we talk to them it seems clear that it wasn't just your garden variety fainting, but rather a fainting spell caused by a dangerous arrhythmia, then those people are also at elevated risk.
- If they haven't had any symptoms, then they fall into the lowest category.
The second question is: Is the electrocardiogram (ECG) abnormal on its own, or was the abnormality provoked by some other factor like a medication? We call the abnormal telltale ECG finding a "type 1" Brugada pattern.
Was the ECG pattern spontaneously abnormal? In other words, did it have that classic telltale abnormal characteristic on its own? Or did we only see that telltale ECG pattern after a provocation with a medication like Procainamide? The folks who have that provoked form of the ECG pattern tend to be at much lower risk than the people who have that spontaneous ECG pattern.
When we cross the two above factors together, we can start to estimate the risk of cardiac events that somebody might have annually. However, the data are quite biased, because they're generated from people who came to attention and thought to have a higher risk of having events. So when we talk to patients, we have to be careful about quoting absolute risk estimates.
Cardiac event risk statistics
Can you tell me about the statistics for risk of cardiac events?
It seems that the folks who’ve had a fainting episode that might be due to an arrhythmia, and who have a spontaneously abnormal ECG pattern have a risk of a dangerous event that's probably about 2% to 4% per year. However, folks who’ve had a fainting episode that might be due to an arrhythmia, but have only a drug-induced ECG pattern, have a risk of events that's probably on the order of a little less than 1% to about 2 ½% per year.
People who are completely asymptomatic and have a spontaneously abnormal ECG pattern have a risk of events that's probably on the order of about 0.5% to 1 ½% per year. People who are completely asymptomatic and have only a drug-induced ECG pattern are at very low risk of events that are probably about 0.1% to 0.5% per year.
The people on the lowest end of the spectrum of risk are people that we feel pretty comfortable simply watching. We often talk about implanting a defibrillator in the people at the highest risk end of the spectrum of risk.
But the people who fall into this intermediate category, who have a spontaneous type 1 ECG pattern but no symptoms, are the hardest people to help counsel in the clinic. They're at an elevated risk, but we just have a hard time really predicting the future in those individuals, and so we often have more detailed conversations about what to do next.
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