sick sinus/chronotropic incompetence

I had my first episode of AFib in 2002. I had my RF ablation in 6/10. Once the ablation took is when all of my problems really started. It turns out that my AFib was just a symptom of sick sinus syndrome, specifically chornotropic incompetence. I have had ectopy free periods interspersed with weeks or months of frequent PACs since my ablation. My EP just implanted an on demand pacemaker last week. Of course I have to recover from the physical trauma of the implant but I have improved every day. My resting heart rate was in the low 40s before the PM was implanted. It is set at 50bpm from 6am-11pm and then 40 from 11pm to 6am. I have not felt this good in months. I plan to resume my cardiovascular training next week and will be released to full duty as a fireman in about 4-5 weeks. This has been a long, long journey and I have been through many doctors along the way but I was lucky enough to find the right one that sat down and really listened to my situation and reviewed all of my records. Thanks to all of the advice and support along the way.

Hi Tim,

Glad to hear that you are doing well. I often contemplate as to just how many AFrs have AF that is associated to some extent with undiagnosed milder variant of SSS.

Regards,

Mike

Hi Tim,
So pleased to hear that you seem to have got to the bottom of your symptoms. I'm interested in any information as to how your diagnosis was eventually determined by your E.P. What were the distinguishing features or differential diagnosis? I have often wondered about my own experience with AF which does not seem to follow what many experience on this board. Consequently, I am a little suspicious of possibly sick sinus syndrome and hence an ablation may not be the total answer. Your comments (and any comments from others) would be most appreciated.
Kind regards,
sujo

Hi Sujo,

The chronotrpoic incompetence was demonstrated during 4 different stress tests I had between Sept. of last year and Jan of this year. My heart rate went up to 115 and stopped increasing no matter how much the workload was increased.

The term sick sinus syndrome is an umbrella term that covers any dysfunction dealing with the sinus node. One major factor for my EP was that the only 2 documented times I was in AFib (10/02 and 4/07) my ventricular rate ranged from the mid 50s to mid 70s. Typical ventricular rates are 150 plus. Last May when I became highly symptomatic, my doctors jumped to the AFib diagnosis. However, through all my time playing lab rate for numerous doctors, they never captured AFib. My holter demonstrated a high number of PACs but never AFib. They were able to induce AFib during my ablation but that was it.

My ablation went well and I had no issues with it. I took it easy for a month and followed the advice of many people on this board. But after the month, this just got progressively worse. I was admitted to the hospital in Sept and Oct with chest pain and shortness of breath. I went through every possible diagnostic cardiac and pulmonary procedure most multiple times.

I am only 40 years old and a pacemaker was not even in the back of my mind when I had my problems and went in for the ablation. Once I got to the right doctor and we discussed everything, I was convinced that it was the answer. I can't wait to get healed up and back to life.

Good luck to you. Do your research and be your own advocate.

I find this topic very interesting. My husband's heart rate never goes much higher than 120 even when he is sprinting. His resting heart rate is around 50 and he has a good exercise capacity. He is 59 and a life long exerciser. I know this is abnormal and he is still having afib after two ablations. He has had all the ekg's/stress test, echo's. CAT scans and they say he is normal.

Debbie

Information on ways to tailor the rate responsive features of pacemakers to the needs of the athlete/exerciser are discussed here. The authors make the point that more than one kind of sensor should be used, and that the clinician needs to take the time to set the sensors according to the patient's need:

[www.medscape.org]

[www.medscape.org]

I have wondered whether a slow heart rate (bradycardia) might be a risk factor for AF, and how this might work, but have not been able to find out anything much. For example, could bradycardia affect total ERP, with the intervals between beats offering a chance for AF to act? In this case, a pacemaker might help reduce the likelihood of AF.

Or could bradycardia be a marker for AF risk factor(s), such as areas of slow conduction ...in which case the pacemaker would not help... at least not by by increasing the heart rate.

A pacemaker could still help if its pacing algorhythms designed to stop AF by pacing were effective... but so far they have not been shown to be effective enough to recommend pacemaker implantation for AFers for their AF alone.

[circ.ahajournals.org]

(I assume that the permanent pacing mentioned refers to maintaining the patients rate a bit over their moment-to-moment natural rate... which could suggest a causal role for a kind of relative bradycardia in AF.)

On the other hand, AFers could benefit if they needed a pacemaker for other reasons:

"CONCLUSIONS: The ADOPT demonstrated that overdrive atrial pacing with the AF Suppression Algorithm decreased symptomatic AF burden significantly >>>in patients with sick sinus syndrome and AF.<<< The decrease in relative AF burden was substantial (25%), although the absolute difference was small (2.50% control vs. 1.87% treatment)."

[content.onlinejacc.org]

Please note: Strictly speaking, the results would apply only to patients with sinus node dysfunction. And note the difference between the difference in impact between the relative effect (Wow!) and absolute effect (Ho-hum).

-- Dick

Tim:

Why would the doctors do an ablation when you only had a couple of episodes of afib? Usually a ablation is not performed until a patient has been given anti-arrythmia drugs which don't work.

Were you taking any beta-blockers before and after your ablation?

Liz

Liz,

My resting heart rate was in the mid to low 30s at the time. From my first AFib episode on, my resting heart rate was always attributed to my enduarance training. Due to the low resting rate, I was not a candidate for drug therapy. As I am sure you know, beta blockers slow down the heart rate. After 7 months of no exercise at all, my resting heart rate remained in the mid 40s. I had no symptoms other than frequent PACs. With my pacemaker, the bottom is set at 50 and so far, no PACs. the only meds I have ever taken are aspirin and coumadin for a month before my ablation and 3 months after. I hope I answered your question.

Tim:

Yes, thank you, I thought perhaps you might have been taking a beta blocker which can cause SSR, this happened to me. I was taking a beta blocker and I also take synthroid for my thyroid---beta blockers can interfere with thyroid hormone uptake so I became hypo. This all led to sick sinus rhythm, I would almost black out when going from an afib episode to NSR. I too had a pacemaker implanted, my pacer is set at the low end of 50 like yours.

Liz

Liz,

My first afib episode resulted in syncope when I converted from afib to nsr. Other than that, I have never had any issues with my bradycardia.

What type of pacemaker do you have? What are the other settings like?

Tim

Tim:

It is a St. Jude, dual lead, it was implanted in 1999, I still have the orginal battery, I do not use it very often. It will record any afib episodes, since your pacer is much newer, you probably have a lot more bells and whistles. I still got afib episodes after getting my pacemaker, however, the last few years my afib episodes have greatly lessened, I can go from 3 months to perhaps 6 months without an episode.

Liz

Thank you Tim for your excellent response and explanation of your situation. Most helpful and informative. Best wishes to you.
Kind regards...sujo