Afibbing: Because CMT by Itself Wasn’t Enough
Updated: Jan 18, 2021
I am a CMTer and I was recently diagnosed with A-Fib. First and foremost, I’m not trying to establish nor suggest a claim that cardiac problems, especially cardiac conduction abnormalities, are caused by CMT, or that they are not. I only want to share my experience so far, what I’ve learned so far, and I want to some insight from my cardiologist on my individual situation.
Cardiac involvement in CMT is one of those controversial subjects. There’s plenty of anecdotal evidence, but there’s not much in published literature. There was a study in 1979 (it’s usually the first search return in Google) that suggests a connection between cardiac conduction abnormalities and especially 1A. There hasn’t been much of anything to support or refute since.
There are some occasional mentions of cardiac involvement in CMT peppered in literature, but even then it’s only a small blip of a mention, without much discussion of findings. Sometimes, these mentions attempt to link certain subtypes (via using CMT associated gene mutations), but still don’t really provide much of a finding discussion, if any at all.
Cardiac involvement in CMT is an area that needs a lot more work. Time will tell, as we learn more, if there’s a definitive connection, or not. But, the topic needs more in-depth study.
So, You See, What Happened Was…
I had a bilateral tonsillectomy in September 2020, and at the age of 47. The surgery was on a Monday, and the surgery was smooth and uneventful. The anesthesiologist opted for a non-neuromuscular blocking med for the general anesthesia. He used what he said was a somewhat newer med that has almost instant reversal properties. The name, however, escapes me. I rolled into the OR about 8AM. I was awake, alert, and communicating in post-op at 9AM. Smooth and uneventful.
The plan was to stay overnight, and in ICU at University of Michigan Hospital, because of my complex neuromuscular respiratory history and current overall respiratory condition. Because anesthesia was able to avoid neuromuscular blocking, I extubated in a snap with no issues, and I was moved into the ICU step-down unit. Again, though, only as a precaution. I was in my room by 1PM, and everything was still smooth and uneventful. That would change.
About 730PM, everybody on the floor seemed like they were as bored as could be. I couldn’t have that, and I wanted to help them to not be bored. All of a sudden, without warning of any kind, I started throwing up. It caught me by total surprise. I was wired for sight and sound, so before I could hit the call button to let my nurse know what had just happened, every staff member on the floor was busting through my door. I had set off the monitors at the nursing station, and they jumped in like I was having a massive heart attack. But, a heart attack is not what was happening.
My little charade to end the boredom turned into an Atrial Fibrillation event. I had never experienced A-Fib. I’ve never been a cardiac patient. Knock on wood, I’ve been able to maintain good cardiovascular health. This A-Fib thing was completely new for me. Two EKGs, in-room monitor, and a 2D Echo all concur that it is A-Fib. With a resting heart rate of an erratic 120 – 160, they started pushing Cardizem in the IV to control it.
The Cardizem helped, after a couple of hours, to keep my heart rate around 100 for most of the night. By the time the 2D Echo was taking place the following morning, my resting heart rate was hovering around 120, and only slightly erratic. I was still in A-Fib.
The preferred treatment for A-Fib is to manage the rhythm. However, instead, they were managing the heart rate with me. Why? Rhythm control requires the use of blood thinners, and I wasn’t even 48 hours post-op. Blood thinners post-op can be a bad thing, especially with tonsillectomy. Why is rhythm control with A-Fib important though?
A-Fib, or Atrial Fibrillation, is a condition in which the top half of the heart (the atrial chambers) beats fast and erratically (fibrillate) while the lower half (the ventricle chambers) beats normally. A-Fib has many different causes, including sleep apnea. Of course, being a CMTer who has sleep apnea at the hands of my CMT, I’m in a higher risk category. During A-Fib, blood doesn’t flow through the atrial chambers normally. Instead, it can kind of swish and can even become static (staying still). When blood becomes static, it can coagulate and form a clot. This clot can travel and cause a stroke. Because of this, A-Fib is preferably combated by managing the rhythm from erratic to a constant rhythm, and blood thinners are a part of the therapy.
I was precluded from blood thinners for at least 14 days post-op. So, inpatient cardiology opted for rate control. Fortunately, I am in the lowest risk category for stroke, and that provides some comfort in the approach. As luck would have it, while on rate control, I spontaneously converted back to normal sinus rhythm overnight Tuesday into Wednesday morning. I woke Wednesday morning with no A-Fib. This bodes well considering I couldn’t be on blood thinners at that time. What caused my A-Fib though?
It All Started When…
I have CMT1A. For years, going back to at least the mid-90s, I’ve had little transient bouts of cardiac arrhythmia that show up without warning, and disappear that quickly. They’ve never been explained; and, not for lack of trying, they’ve never been captured via monitoring. With the event that started that day-of-tonsillectomy Monday evening, the cardiology team was confident that all of it has been A-Fib all along. Ok, so, I’d be remiss if I didn’t ask: is there a connection between CMT and cardiac conduction abnormalities, and specifically 1A? The answer was an interesting conversation with the inpatient team.
By the time I asked the question, the lead cardiologist had already looked into it. They seemed surprised that I asked. Their surprise might have been in how I asked. “Because I have CMT1A, are there any known or suggested connections that you are aware of that establishes a quantitative correlation between not just CMT1A, but CMT as a whole?,” is probably not something that most physicians get from any of their patients. I can see how one might be caught off guard a touch. Yes, I really do talk like that with my doctors. I’m an odd one.
The cardiologist let me know that she found only a mention of a couple of gene mutations that might have something involved, and she said she wasn’t sure if I had those mutations. Well, lucky for her, her team, and me, I know my underlying causative mutation.
I let the team know that my 1A is caused by a duplication of the PMP22 gene, and I asked the cardiologist if she recalled the mutations mentioned in the literature she found. She didn’t recall, but she offered to pull everything up on the in-room computer. Now we’re talking my language.
She opened up the database provided to the physicians at University of Michigan Hospital. She pulled up the search results. The results indicated a paper that made a blip of a mention of cardiac something in CMT caused by a mutation in DYNC1H1, and another blip of a mention about cardiac something in CMT caused by a mutation in the RAB7 gene. The cardiologist team had no idea what any of that meant, but I was able to let them know that those references were to CMT2O and CMT2B, respectively. They were surprised, again, but I’m not a normal patient in any sense. There were no descriptions of what any connection was nor what any cardiac symptom was. It raised more questions that it gave answers.
The cardiologist also pointed to the study from 1979 that I mentioned earlier. This paper establishes a possible connection in a small group of 1A CMTers (68 CMTers with 1A) to cardiac conduction abnormalities. My cardiology team says that, while the findings are interesting, there are several flaws in the underlying data and inaccuracies in the report narrative. They also noted that it is a very old study and there is nothing in the published literature to support or to refute the study. They are not the first ones to tell me this about the particular study.
In the end, the inpatient cardiology team couldn’t make an established connection between any type of CMT and cardiac conduction abnormalities. I was discharged in normal sinus rhythm, and with a Cardizem script until follow-up with outpatient cardiology. Fast-forward to early December.
The Current Sitch
Since hospital discharge in September, while taking the med for rate management, and nothing else for the A-Fib, things have been fun. A-Fib is just one of those fun things. Yeah, let’s go with fun. A-fib is fun. I’ve been having several episodes a week, but nothing that hangs around for more than an hour, and most have been less than 15 minutes. I finally saw my new cardiologist the first week of December, approximately ten weeks since my A-Fib event while inpatient.
I know you all know the doc was not getting out of there without doing an in-depth Q&A with me, that I wasn’t going to give them an opportunity to quietly slip away. So, me being me, I asked if he knew of any specific connection between my 1A and cardiac conduction abnormalities such as A-Fib, especially given the expression of PMP22 in cardiac tissue. The response was thorough, and we had an enjoyable conversation.
According to my cardiologist, as my A-Fib pertains to me, “in theory, there might be a connection, but I’d have to cut you open, grab a chunk of heart muscle, and put it under a microscope; and I’m just not going to do that.”
The cardiologist went on to explain that PMP22, the gene that is duplicated thereby causing 1A, is also expressed in cardiac muscle and in the nerves that control the heart and the rest of the cardiovascular system. He explained that although the gene is expressed in those anatomies, the gene’s function there is not understood. He further explained that it’s possible that the same type of pathology in peripheral nerve myelin that’s caused by an over expression of the PMP22 gene could take place wherever the gene is expressed.
My cardiologist repeatedly emphasized that cardiac conduction involvement in CMT and especially in my 1A, if any, is not known or understood. He concluded that if there is a connection, at this point in time, treatment options and decisions would be the same as if there isn’t a connection. My cardiologist also feels that all of my little episodes of arrhythmia over the years have been A-Fib events. He also cautioned that A-fib is quite common, and that I have at least one very common risk factor: sleep apnea.
I’m not a physician or a clinician. I have no formal medical training. I do have a decently firm grasp on a lot of things related to CMT though. My tonsils were removed because of my CMT induced respiratory issues. In the process, boom, A-Fib. Does this mean that my CMT caused my A-Fib? I don’t know. I only know that I had, in the very least, the same chances to develop A-Fib as a non-CMTer. There isn’t much in published literature about CMT and cardiac conduction issues, but there is a lot of anecdotal evidence in the CMTer community.
The disparage between anecdotal evidence and quantitative scientific evidence leaves this as a controversial subject. The consensus of the CMT expert community is that there is no established connection. From a patient perspective, the controversial nature of this subject suggests that much more research needs to happen in this area.
A-Fib is an electrical problem in the heart tissue. There is no indication that my cardiac muscle is weakened or otherwise diseased at the hands of my CMT, or at the hands of anything else. For all intent and purpose, my A-Fib is a stand-alone issue, until proven otherwise.