Settings and adjustments for arrhythmias

I have a Medtronic Ensura dual chamber pacemaker for tachycardia/bradycardia syndrome (implanted in 2018).  A few days ago I returned to my clinic and they looked at NCAP (non competitive atrial pacing) and APP (atrial preference pacing). 

I was told NCAP helps prevent atrial tachy arrhythmias by avoiding (delaying) pacing after a premature atrial contraction (PAC)


APP helps prevent atrial tachy arrhythmias by overdrive pacing after a PAC which can help stabilise and maintain consistency in atrial activation. 

My EP arranged for me to have NCAP switched OFF to see whether overdrive pacing provided by APP might work more effectively on its own to stabilise any PACs which are a known trigger for my Atrial Fibrillation (AF).  So far the results have been really encouraging.

During my check, the technician picked up some under-sensing of my AF on one of my stored atrial electrograms during a long episode on the 4th February. This was concerning although not altogether surprising.   The technician therefore adjusted my "atrial sensitivity” to the highest level, from 0.30 mV to 0.15 mV (where the lower the number = the more sensitive the pacemaker).  

I was told my Mode Switch (which is a feature on most pacemakers to prevent the tracking of a fast arrhythmia) should work better too with the atrial sensitivity level set higher (although probably means more Mode Switches).

When I joined the PM Club I was always reading how important fine tuning of settings were to get the most out of our pacemakers to suit our lifestyle.  It has taken me almost 5 years to get any real changes made to my current Settings but I am happy it is finally happening, albeit with some scepticism that I can work wonders on my arrhythmias with my pacemaker alone.  But why shouldn’t I at least try to optimise my Settings, to make them work better for me?  

While I accept the limitations of my pacemaker to treat an arrhythmia like AF, there is no harm in asking our EP’s what more our pacemakers can do for us.  It is an amazing little device and in my opinion, often under utilised. Good luck to everyone battling with an arrhythmia like AF, although I am sure you will have some pacing success stories too?


Good for you!

by Lavender - 2023-02-23 16:41:09

I'm sure most EPs are not accustomed to having such well read patients with a good deal of knowledge to seek solutions. I personally think our first few pacemaker checks should be done by very well experienced manufacturer's reps who are trained in all the facets of each device. 

I am glad too that a setting was discovered to be more sensitive to your AF. This can let them know when you're having much more than formerly discovered episodes of it. 

It takes so much for you to get out there, transport to the appointments and get and give knowledge with your team!

So proud of you! As always!πŸŒΈπŸ’—


by AgentX86 - 2023-02-24 01:22:38

IME, factory reps only get involved if there are problems. The only time I've had one involved (by phone) was that the clock couldn't be set right (time zone screwed up).  The problem was that the PM was set up wrong initially.

Yes my EP was a little surprised by my questions

by Gemita - 2023-02-24 02:59:33

Lavender, thank you.  I was quite proud of myself too for managing to get my point across for a change.  I think my EP knew I had been doing a bit of research on some of my settings.  I was surprised he even had the time to listen to me, since his clinic was running very late again. 

I agree manufacturer reps are good to have around and my NHS clinic technicians often have to send stored electrograms to them to be read to confirm the rhythm disturbance present.  

It will be interesting to see the real % time I am in AF following my atrial sensitivity setting adjustment.  I can ask about this at my next check.  Aren't we all good students here?

AgentX86, I agree, manufacturer reps in our clinic are not usually in attendance and are only contacted when a technical issue needs resolving.  My clinic technician for example had to consult the manufacturer rep about one of my stored electrograms I recall because they couldn't agree on an arrhythmia diagnosis.  The manufacturer rep had no difficulty confirming a long episode of multi focal atrial tachycardia which occurred during a Covid episode

Complete Respect to You

by SeenBetterDays - 2023-02-24 10:53:44

Hi Gemita, I just wanted to say how impressed I always am by how much research you do and thank you for sharing so much of your knowledge with the group. I'm so pleased that all your reading has paid off and brought you some tangible benefits. I remember at my first pm check I joked with the EP that I felt that I needed to attend a training course to get my head around all the technical aspects of my new machine! I am continuing to read and learn and, as you have said, it's just so much better when you are able to have a two way discussion when going for your check. I'm glad that you are seeing someone who has taken the time to answer your questions. You always take the time and care to answer ours. Hats off to you.

Thank you Gemita

by _Claire_ - 2023-02-24 12:59:57

I totally agree with Lavender and SeenBetterDays! I am always so impressed with Gemita's knowledge and research. I also want to say thank you to Gemita for all of the time you spend giving information and advice to us all. You manage to be honest and truthful but also reassuring and calming at the same time, when discussing heart related matters and worries. Also many others too that spend a lot of time and effort in replying here. 🌷


by Aberdeen - 2023-02-24 14:23:59


           I am continually amazed about how much you know about pacemakers and the technical side of them. Your contributions to this forum are much appreciated!

What lovely words

by Gemita - 2023-02-24 14:51:30

Claire, SeenBetterDays and Aberdeen, thank you all for your generous words.  They mean so much.  I have to confess I love trying to help others because it also helps me to understand the subject(s) more as well, particularly when I have to write things down, so I am really being quite selfish, not generous with my time.  Each one of us makes an important contribution to this Club, bringing our own unique experience and health condition along. 

SeenBetterDays, I appreciate your situation is difficult with a reduced Ejection Fraction and reduced energy levels, but I see you have gone ahead with left bundle branch pacing.  I am not sure if it has been completely successful and whether you have benefited in terms of your overall health and ejection fraction but I do hope so.

Claire, you are one of our Micra leadless guinea pigs, young and energetic and if anyone can make a leadless pacemaker succeed, it is you.  We will be watching your progress with a great deal of interest and learning from you too, I hope.

Aberdeen, your journey has not been without its difficulties either and yet you have miraculously managed to turn everything around, particularly your fall in your ejection fraction after the placement of your CRT.  Long may your success continue.

PM Settings

by Flo - 2023-02-24 19:07:55

Gemita, I am so glad your new EP listens to you and works with you.  I would like to echo the well said comments above and thank you for the help you give. 

My pacemaker checks show the PM stops numerous afib episodes from occurring. 

Glad you feel better!

by Rch - 2023-02-24 19:24:55

Hi Gemita, I'm so glad you feel better with the new settings!!! We need you in this club to continually help us with your opinions and suggestions!!!!

As to the settings themselves, you have Medtronic Ensura. I have Boston Scientific Accolade implanted in 2022. I looked up on the BS website on APP and NCAP. The Accolade has no NCAP but has APP/ProACt algorithm which automatically programs in response to a PAC to prevent or thwart an AT or A Fib. I honestly do not understand how the algorithm works!! May be you or others on this forum with more engineering background could explain it to us how the new Boston Scientific pms work!!! It would be very educational to know that especially for those who are very prone to A.Fib, A.Tach. Every time I sense PACs, I go into jitters whether it's a prodrome of oncoming A Fib. and stop everything I'm doing!!! Thanks


by Gemita - 2023-02-25 04:07:04

Flo, thank you for your kind words.  I was very interested to read that your checks show your PM stops numerous AF episodes from occurring.  This is truly wonderful news and may be it would be helpful to learn how this occurs and what programs your pacemaker has running? 

Even though I still have intermittent AF with some difficult symptoms, I know for certain (from diary notes) that my arrhythmias are calmer, and better controlled with pacemaker therapy.  My QoL before my PM was extremely poor and life really wasn't worth living, so something had to be done.   

I was told recently the most common reason for reprogramming a pacemaker at the time of follow up is for an arrhythmia so it makes perfect sense to do everything we can to optimise our settings.  I hope you continue to benefit from pacing therapy too although I realise you are also helped by your meds


by Gemita - 2023-02-25 04:16:50

Hello Rch, your comment, "every time I sense PACs I go into jitters" resonated with me too, although I would suggest it is your heart going into “jitters” not you personally since you sound very calm about these things.

I will try to explain the purpose of APP and why it can be so effective to “help” prevent the onset of an atrial tachy arrhythmia like AF.  Of course we all need to remember a specific Pacemaker feature like APP is only another "potential tool” in the cupboard to use against AF since AF is so difficult to effectively treat.  Short to medium term success with an ablation is possible and appears to be the most effective treatment we have at this time, but it is still far from a perfect treatment and carries its own risks, so why not try to utilise what we currently have available in our pacemakers?  Makes perfect sense to me.

Using atrial intervention pacing to counteract atrial tachy arrhythmias may work well for some of us.  It does for me.  Triggers for AF are well known but my biggest triggers by far are from (1) atrial premature beats (APBs) (also known as premature atrial contractions (PACs)) that can originate from multiple atrial sites (2) the long sinus pauses that I clearly feel after an APB.  Increased vagal tone (3) is also another major trigger for me. 

Many currently available devices have algorithms that can be activated in order to reduce the number of episodes of atrial arrhythmias by suppressing APB activity or reducing the short–long sequence seen with APBs.  These algorithms aim to overdrive pace the atrium by pacing at a rate just above the intrinsic rate or by ‘‘smoothing’’ the atrial rate by pacing after APBs, thus preventing short–long cycle lengths associated with APBs.  This is what APP aims to do.  

When I had both NCAP and APP in operation, it appeared to me that they were effectively competing with each other, so having NCAP turned OFF allows APP to work more efficiently.  Some models of Medtronic and perhaps your own pacemaker Rch, may have a specific Rate Smoothing feature (mine doesn’t), but APP does something very similar.

In those who have vagally mediated AF (or shall we say bradycardia induced AF) - the prevention of a sudden reduction in atrial rate which can trigger APBs and then lead to AF, can be eliminated with effective atrial pacing (or naturally with vigorous physical exercise although this is clearly not practical when we are trying to sleep)!  

The early recurrence of AF when we return to normal sinus rhythm following an episode, can be difficult to treat.  This has been addressed by some algorithms which allow high rate atrial pacing immediately after the termination of AF.  Some devices have the ability to treat atrial arrhythmias using anti-tachycardia pacing in a manner similar to ICD therapy for ventricular tachycardia.

Of course when we succumb to AF, there are other important algorithms that help to protect us like Mode Switching which so effectively prevents the tracking of an atrial tachy arrhythmia but that is another subject.  I hope other members can contribute to this discussion with their own favourite algorithms to help treat AF or perhaps this might make a nice new post for you Rch?

You go girl! or Research Rewarded

by Gotrhythm - 2023-02-25 13:27:14

When I read your post, I confess I thought wow. Even Gemita had to find out for herself, five years after getting a pacemaker,that there was a setting that could be tweaked to give her a better quality of life!

When I joined, about 4 years after I got my first pacemaker, I didn't even know there were settings! What a revelation that was! And how stupid I felt that I had lived 4 years without questioning when I could have had a much better quality of life all that time.  Oh well.

And then I learned through experience that the more more knowledgeably I could talk about settings, the more willing the professionals were to take the time to listen to me and try some adjustments. Your story illustrates that point perfectly. Even though the professional was busy and already behind, he took listened because you could talk in his language about how the settings were interfacing with your particular arrythmias.

I'm so proud of you for continuing your research on what your pacemaker is doing and how it interfaces with your particular arrythmias. I'm proud of you for taking responsibility for changing what you can and also for continuing to add to your knowledge of pacemaker-ese.

I'm impressed, and very, very happy that you are enjoying an improved quality of life.


by Gemita - 2023-02-25 19:29:57

Gotrhythm, thank you.  My life has definitely improved with my little device and yes 5 years is a long time to wait for a Settings change that I played a part in.  At least it is progress and I have needed those five years for some serious learning anyway.  Pacing is not an easy subject to take up, is it?  

As a matter of fact when I was in the clinic last week one of the technicians (semi retired) suggested that it wasn’t necessary for me to understand about these things and that it might be best to leave my care to them.  I remembered in one of your posts you mentioned you had had a similar experience. I told him that I actually enjoy learning about my pacemaker and that I would prefer to understand what is happening, rather than being kept in the dark.  I don’t think they have too many elderly patients asking them technical questions although most of the technicians I have met have been more than happy to engage.  

I like my new EP Gotrhythm and I am very lucky to be under such an excellent teaching hospital in London.  I just wish we had better access to some of our pacemaker records, then I wouldn’t have to ask so many questions or sound as though I don’t trust them with my Settings.  I have to formally request a "Summary of my Settings" or any data that I want to see but they take so long to arrive.  I have to send a copy of my passport for proof of ID with my request for data.  I requested Settings details last September which are still awaited.  If I had better access to my records, I wouldn't need to keep asking questions and use up so much of their valuable time.


by Rch - 2023-02-26 02:10:36

Thanks Gemita! 

My basal atrial pacing rate is set about 10 beats higher than my intrinsic HR, and that seemed to have minimized the PAC burden a bit! Further the APP/ProACt algorithm in the Boston Accolade may have further reduced some. So, my overall PAC burden is very low, may be 5-10 a day on the average, some days are worse than others! On a long flight, even one is too many to arouse fear but I convince myself that A Fib is not life threatening and I should just stay calm! I always carry with me in my wallet a 25 mg Beta Blocker whenever I get out of the house! My last A.Fib was in 2015 and haven't had any since. All I'm on, are a beta blocker and a DOAC. I had deferred ablation with PVI which was recommended to me by my EP in 2015. But if I had had it, I would have thought the ablation treated my A Fib! 

Once again, thanks for your encouragement and support, and hope you will continue to feel better with your new settings!

PAC burden

by Gemita - 2023-02-26 07:11:40

Rch, your AF and PACs seem well under control with your current lifestyle and only a few essential meds (and pacemaker of course).

Yes there is no doubt that a higher base rate setting helps many of us (it certainly helps me too and mine is set at 70 bpm).  It may not though be enough to smooth out all our atrial premature beats (or shall we call them PACs) when these occur, which is why additional algorithms like APP can help to prevent PACs deteriorating into AF.  

There are other settings though that can affect the smooth working of algorithms like APP and render them less effective.  For example I was told my APP/overdrive pacing is limited to 130 bpm (my upper set rate) as it could trigger another atrial arrhythmia by pacing the atria too rapidly.  I do understand this but what I didn’t realise is that my PACs are sometimes coming in at “too high rates”, so APP/a higher Base Rate setting may not be enough to suppress PACs 100% of the time.  I never knew that PACs could come in at rates higher than 130 bpm, but I guess PAC runs could intersperse with runs of tachycardia, AF or Flutter.  Maybe this is what is happening?  Well actually I know this is happening from my last check which is why the technician set the atrial sensitivity for AF detection to the highest level.   Anyway, for the moment I am having a really good outcome with NCAP switched off, so I am not complaining.

Although AF is not a dangerous arrhythmia as is say sustained VT, it is still very important to keep AF under firm control, to prevent worsening symptoms which could lead to heart failure and other serious health conditions.  Nice chatting with you Rch and hope you continue to do well too.  

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