Premature Atrial Contractions (PACs)

Premature Atrial Contractions (PACs) are amongst the most common forms of arrhythmias.  It is due to the premature discharge of an electrical impulse in the atrium, causing a premature contraction.

Therefore, it is named “premature atrial contraction,” or PAC.  A PAC is premature, because the it occurs earlier than the next regular beat should have occurred.

Symptoms of PACs

Most often, patients with PACs complain of palpitations.  However, rather than reporting a sustained racing heartbeat, they usually describe a “missing” or “skipping” beat.  Some patients even feel that the heart has “stopped” while others describe a sensation of “flip-flop.”  This is due to the fact that the PAC comes too early (prematurely) in the cardiac cycle to have resulted in an effective pulse or heartbeat.  Therefore, no heartbeat is felt until the next regularly-timed heartbeat occurs after a pause (so-called compensatory pause).  Incidentally, the beat after the PAC usually occurs with stronger contraction than usual and can be associated with an urge to cough.  Symptoms of PACs are virtually indistinguishable from those of PVCs as the physiological effects are identical.

Causes of PACs

In the majority of cases, PACs occur in normal healthy individuals without any evidence of heart disease.  Stress or stimulants such as tea, coffee, or alcohol can increase the frequency of PACs.  In the minority of cases, PACs can be a sign of underlying heart condition in the atrium associated with hypertension or valvular condition.

Consequences of PACs

The great majority of PACs are completely benign and require little if any treatment at all.  As mentioned above, in rare cases, PACs may be the only sign of underlying heart conditions and these should be ruled out with appropriate evaluations. However, PACs may change into

  • Atrial Flutter:


Evaluation is similar as with any patient first seen for palpitations  and arrhythmias and includes blood tests, EKGs, as well as echocardiograms.

Treatment of PACs

As most PACs are benign, treatment is optional and is usually geared toward alleviation of symptoms.  Medications such as beta blockers or calcium blockers are often used but with mixed result.  Most important treatment, after ruling out severe underlying heart conditions, is patient reassurance and teaching of various coping mechanisms.

Comments 73

  1. Want to offer a data point wrt rhythm issues and the COVID vaccines.

    I had a massive LAD heart attack a decade ago. A year ago, after having lost ~80 lbs and been able to wean myself off of all meds except 6¼ mg qd of metoprolol succinate, I had a severe atrial fibrillation-quivering which led to 30-35% ejection fraction loss.

    I’ve since lost another 40 lbs and had a successful cardioäblation which restored my ejection fraction to 45-50%. I have resumed taking 25 mg qd metoprolol, 40 mg qd valsartan, and 5 mg bid Apixaban and just stopped my 5 mg qd lisinopril because heart rate and blood pressure was too low. Holter Test show I have on average a PVC and a PAC every minute but I rarely sense them.

    In addition to transformed diet (whole-food vegan, no salt-oil-sugar), I walk at least 5 mi a day in 90 min, six times a week.

    I just received my second Moderna booster. I also had the Moderna for the initial vaccine series. Throughout, the only adverse reaction I’ve had is a robust flu-like response. Today’s booster doesn’t feel as intense as the first three were, but I’ll know better in the morning. I’ve had no adverse reactions to the Moderna vax vis-à-vis my heart.

    I’m in no way questioning / denigrating other folks’ experience here… it’s just that people who aren’t having problems tend to not post because, why would they? But, for a complete view, I think it’s helpful to report the success stories. For me (and my best-wife), Moderna vaxes have been terrific and non-adverse.

    1. I have MS and SVT with PAC and Branch Block, as well as Autoimmune Thyroid Disease. I eat healthy, never drink alcohol and exercise via Yoga and Tia Chi as I have done daily for the last 38 years. As I am older and struggling more with symptoms and energy, the Moderna Vaccines & Boosters have breathed new life and energy back into me. I pray for a cure for Covid but I don’t want to stop taking the vaccines as they greatly improve my quality of life.

  2. I had the 2 rounds of Pfizer vaccine in September of 2020. In November I started to feel the same way. Pressure in my stomach sometimes also in my throat with the occasional flutter or missed beat. No other symptoms except the urge to couch at times. It lasts for a bit then goes away. Sometimes days without it. I’m thinking it was the vaccine. I’m scheduled to see my PCP again and push her to get to the bottom of this. If anything it’s annoying. I’m 46.

    1. I also had the two original vaccines for COVID and the booster. After the booster I developed PACs. Feels like my heart is flopping around in there and kinda takes my breath.

      1. The same thing has happened to me but mine started before my booster and they definitely have not gone away. I’m 36 years old.

    2. I thought I would mention something that I’ve recently found helpful. Research taurine and L-arginine supplementation. It seems to really calm down episodes.
      I’ve been taking a few grams a day of each and the flutters have stopped. Yeah. The vaccines have been a real problem for so many people. Time for us to take our own health into our own hands.

  3. I have recently been diagnosed with pacs and pvcs. I never had these until I have the second Modena vaccine. No doctor out of multiple appointments with multiple cardiologists and primary care would entertain the possibility that it could have been the root cause. The last cardiologist I went to was the first to say that it might have caused, but may have not as well due to not enough known about the vaccines. I am to the point that I don’t care what caused them, I just want them to stop!

    1. I have had on and off palpitations most of my life, but mine have become almost constant since the second vaccine. Doctors think I am crazy, but it is true. They happen many times every day now, whereas before they would be maybe once per month or so.

      1. After having COVID, I had the booster several weeks later and started to feel fatigued believing I was experiencing long COVID. I now am having PAC’s.
        I truly believe there is a correlation.

    2. Interesting. I just recently had my first prolonged run of PACs. I had the Moderna vaccines in April. I think I have had short runs of them occasionally for a year or more. I had noticed that I had more of them when I was using diphenhydramine as a sleep aid. I used it again recently for a bee sting. Emergency room doc didn’t think there was a connection but I read that increased arrhythmia is a potential side effect.

      1. Hi ! I found that using diphenhydramine, as a sleep aid was causing horrible heart palpitations about two years ago… You are definitely correct… There are definitely are rhythmic affects with diphenhydramine

    3. Charles… I could have written your note. I too have a pre atrial beat that started the afternoon of my second Moderna shot back in February. I was just in to see my cardiologist.

      I have blood pressure machines and a Kardia Mobile. The heart monitor shows the irregular and the Kardia shows the pre atrial beat.

      No physical symptoms.

      Sure wonder if others who got the Moderna got more than they expected.

      1. Hi,
        I`ve had my first booster (Moderna) and I `m due for
        my 3rd plus fluvax together!
        I have PACS which coincidentally started soon after my 3rd (booster) MMMMMMM?
        In addition I got BELLS PALSY (face frozen on the left side of my face!) which has taken 6 weeks to return to normality.
        I read an article in the LANCET (UK MEDICAL Journal)That VACCS might cause BELLS PALSY but the benefits for the public outweighs !
        I`m suspicious about these VACCINES now!

    4. I was just recently told I was having PAC’s during my sleep study for sleep apnea. I will be seeing a cardiologist in about 2 weeks. I have had multiple health issues since I took the Moderna vaccine. Cholitis, which happened about 2 months after my 2nd dose, even though I just had a clear screening colonoscopy 1 month before that. I also am now having PAC’s during my sleep when not using my cpap machine, sleep doctor says the PAC’s are because my oxygen level goes too low. I was one of the lucky ones to get covid-19 breakthrough case 4 months after being ‘fully’ vaccinated. 🙁

    5. Me too I have pacs now I was fine before the vaccine 💉 😔 I’m so sad and stressed if you want. To chat my num is 5599096063

    6. I am 31 and dealing with something similar. I considered the vaccine but I was vaccinate in later January. I figured that it was possible i had covid after vaccination which triggered my symptoms.

    7. I was just diagnosed with PACs. Had Moderna Jan and Feb. did not have last year. I feel the covid vaccine caused this problem. My exercise tolerance has also decreased.

    8. SAME HERE! Mine began 2 weeks after 2nd Pfizer vaccine!!! Now they won’t go away, I was put on Atenolol and that’s causing me diarrhea.

    9. I’ve been having the same issues after my second Pfizer vaccine. I’ve been told it’s stress, too much caffeine, need to lose weight, etc. I have reduced all of these things, increased my anti-hypertensives and was put on Corey then switched to metoprolol with minimal resolution. I have a implanted loop recorder now and told it’s “just PACs” with occasional inappropriate tachycardia. These frequent skipped beats have greatly impacted my overall well-being and quality of life. Although I’d like to know the cause, more importantly I want to feel normal again. Lump in the throat, sometimes short of breath, fatigue with minimal exertion at 42. Ridiculous! Hope you get yours resolved.

    10. I have PAC’s and intermittent tachycardia after my second Moderna dose. Nothing before and I’m young…I’m 35 and seeing a heart doctor. Smh.

        1. No I’ve had PACs since the booster of the Moderna. Kept thinking it was hormonal because I get hot and sweaty. I been past those days I’m 66. 3 months ago had an echo of heart and wore a monitor for 24 hours. I was having lots and lots of PACs. I firmly believe these vaccines are going to cause us to see things go wrong with our bodies for years to come cause there is toooo little known about these vaccines.

        2. No I’ve had PACs since the booster of the Moderna. Kept thinking it was hormonal because I get hot and sweaty. I been past those days I’m 66. 3 months ago had an echo of heart and wore a monitor for 24 hours. I was having lots and lots of PACs. I firmly believe these vaccines are going to cause us to see things go wrong with our bodies for years to come cause there is toooo little known about these vaccines. This is my first time being on here

    11. I had the same thing happen after my Pfizer and also have heart palpatations that come and go and some other issues. Also never had problems before!

    12. I to am diagnosed with PAC,s. Started after my 3rd booster with Pfizer. We don’t know much on the vaccines. Will see a cardiologist on 1/7/2022 Will update. Maybe we all should start a blog / Facebook on our concerns and symptoms. Just a thought.

    13. Mine began 4 days after my Pfizer booster. The only other time I had these were after my first round of vaccines. I didn’t make the connection the first time. Just thought I was stressed, but this time they were much worse and lasted a lot longer. I have been having them Anne 12/26 and only now are they starting to go away. The doctors are also not taking this association seriously for me.

    14. I started having PACs about 10 days after my second Moderna vaccine as well. 7 months later I went into atrial fibrillation. This was a first time event with no history of heart problems.

  4. I have pacs during sleep and I wake upon evertrime. I am acared. Been to cardiologist nany times, but he does not say much to me. Even when I ask questions he is invassive. During the day I don feel much my pacs.

    1. I am worried about palpitation. Everynight I wake up with palpitations. Went to see a cardiologist, and he did not explained anthing to me about this condition. He always say that I have extra beats. I have metropolol for the symptoms but I am too scared to take the pills. Anybody experience palpitations during sleep more than during the day?

      1. Hi! I have PAC and PVC. I take diltiazem and metoprolol. Take it. It helps. And yes I’ve experienced the episodes more at night too.

    2. Lynda you just described me. They keep me from going to sleep comfortably and they wake me up every day. I walked up my stairs and get heart palpitations as if I had been exercising for 15 minutes. I’m sorry this is also your story!

  5. I have been having PACs for a few months. It feels like my heart is going to come through my chest, a lump in my throat and a deep throb under my diaphragm! ECHO dx PVCs. I’m on a beta blocker, antidepressants, HCTZ. Scheduled for 24H monitor because 30 second EKG didn’t pick them up! Of course not, I get PVCs at bedtime. Are sleeping pills bad to use too? Also I’m worried my symptoms aren’t being taken seriously; cardiologist did not apical pulse for 60 secs, more like 5-7 secs!

  6. Many sites treat PACs as benign, but there are several recently-published (last five years) that show that *frequent* PACs are associated with a higher risk of afib, stroke, and death.

  7. Potassium eliminated my PACs within 18 hours — none for 4 months.
    For 15 years had had increasing PACs. Last one and 1/2 years had increased to average of one PAC every 7-8 seconds on average. Magnesium supplements had no effect. Blood tests average Potassium close to 4.0 Saw 4 cardiologists over 15 years – Ekg documented PACs. Echocardiograms neg times 3. I am a neuroscientist; was studying ion transport in neurons. I read that bllood potassium can be normal but reservoir pool of Potassium in cells can be low. Daily recommended Potassium is 3600 to 4700 mgs a day. My diet, very regular, averaged 1600 meq a day. Walmart- bought Nu-Salt = potassium chloride. Took 1000 mgs three times during day on Thurday – total 3000 mgs. Friday morning checked my wrist pulse and pO2 CPAP monitor and I could not believe it – for 15 years without exception my pulse on the monitor varied from 58-72 every minute. – Friday AM my pulse for 7 1/4 hrs varies from 62-64. Palpated my carotid and felt an entirely regular pulse wave, with a neats of same intensity.
    Imhave continued to take 3000 mgs pot. chloride ‘salt substitute’ for 3 months. Still no PACs.
    My retired life for 8 years has been very low stress. Have not yet had an EKG — but my CPAP pulse monitor is best one used by best sleep study labs.
    There does not seem to he anything I can find in literature to confirm such a finding in my case.
    Perhaps the Two are not causally related……….. ? ?
    I would very much welcome any feedback .. re how naive I am re literature, cardiology, etc.

    1. have had the same problem. Being a long standing health professional, I thought that K+ was still the answer for this form of PACs. I will be trying more potassium supplements to reduce this annoying feeling. will let you know

    2. Hi Charles, I also had developed arrhythmia for the first time, and thought it was perhaps because of getting older (66). However, I believe you are on to something with electrolyte imbalance, that being the cause of mine as well I believe.
      However – here’s the important point – my arrhythmia I believe was caused by TOO MUCH potassium (called hyperkalemia).
      In order for electrical signals including those that drive the heart to be transmitted well, there has to be a proper BALANCE between the minerals, especially as I understand it potassium and sodium, though I believe magnesium probably comes into play as well.
      In my case I was put on Losartan potassium for high blood pressure about a year ago, I was taking the potassium/sodium salt for seasoning my food, plus I love bananas and knew they were high in potassium to control my BP, so for weeks/months before my doctor heard the heart arrhythmia, I would probably have 2 or 3 bananas a day – too much total potassium!

      My family doctor said, no potassium isn’t the issue because we did a blood test with your physical, and your potassium was in the middle of the normal range.
      However, that just tests the amount in the blood stream, and I was fasting before going in for the physical, no losartan potassium, no potassium salt and no bananas to load potassium into my blood stream – but THAT DOESN’T MEAN THAT HIGH LEVELS OF POTASSIUM HADN’T BUILT UP IN THE OTHER CELLS OF THE BODY, as I had read an internet article which pointed out.

      So bottom line, I bought an EMAY portable ecg monitor ($99 on amazon, great little machine!) and read up a little on how to read an ecg graph, and learned that a high and pointed (rather than rounded) “T-wave”, usually indicates hyperkalemia, or too much potassium!!

      So I stopped eating bananas altogether to bring my potassium level down, and within a day or two the majority of my ecg readings were normal, whereas before 30-50% showed arrhythmia.

      Also previously my readings before tended to show quite a few ‘bradycardia’ readings (heart rate below 60), and after reducing my potassium intake, now I’m seeing fewer bradycardia readings. I believe all that potassium was dampening the electrical signals enough so that my heart rate itself was a bit depressed, in addition to being more erratic (arrhythmia).

      So at any rate, IMO, both my family doctor and my cardiologist should have looked more seriously into the potassium/sodium imbalance issue as I’m fairly certain now after a month of mostly normal readings that too much potassium was the main cause of my arrhythmia and PVC’s as well probably.

      But I had to diagnose it myself, since my cardiologist never brought electrolyte imbalances up (even though losartan potassium on the list of drugs I take that I gave him), and my family doctor flat-out told me that potassium was not my problem, when in fact, I believe it was the problem!

      There is a lot of criticism of people doing their own internet research and then thinking they are MD’s and that may be valid, but my family members have also found that often they can learn things that ARE useful, that frankly sometimes the doctors miss, and let’s be honest, no one cares about your personal health issues more than you, so we will spend hours researching when the doctor probably won’t – they don’t have the time to with all the patients they see.

      1. Hi George, I am thinking that I may be going through the same thing with Olmesartan. Can you give me an update?

      2. You are correct. I remember reading about a man who loved coconut water and drank 12cans a day and his heart started flipping bad. They found out at the hospital that he was way over the limit. He stopped the drink and the palps stopped. Each can has about 1,000 mg potassium.

    3. My wife has been dealing with PACs and a-fib for several years. This year had a cardiac ablation. Still having PACs. She swears that extra potassium helps, even though her blood levels are “normal”. I’m wondering if you have had continued success using supplemental potassium?

    4. Thank you for posting that. I had sudden pvcs and pacs with first episode a bad one a year ago. In the ER potassium was very low. Symptoms subsided in days following after being treated. Since then I have had them episodically 1-2x month and on metoprolol. Last two months pvcs are every evening. I’m fit and 37. Last potassium level was 3.7 so not super high. Normal echo. I’m going to ask my electrophysiologist about the nu-salt. And I just ate a banana.


    6. I’ve had PAC’s for about 10 years. The last year they have occurred daily, for several hours at a time. Started taking potassium 3 weeks ago and haven’t had a single palpitation since.

    7. Are you still taking this level of supplementation? And aren’t you concerned that the side effects of taking too much potassium? Why did you not believe the levels were too high instead of low?

  8. can PACs and PVCs cause AFIB and heart disese to get worse if not taking Metoprolol that cardiologist prescribed? Have had Ablation and now have pacemaker. Thanks in advance

  9. Cardiologists prescribed pac and ihb with no treatment. Orthopedic doctor prescribed meloxicam or celecoxib for arthtitis and knee pain. Are these meds safe for heart? I need to walk.

  10. Do some Holter tests . See if some strong medication as flecainide might have the effect to reduce them. Compare Holter before and after. You may need a good electrophysiologist for helping you with ablation – one or more.

  11. Thank you all for validating the coughing. Once I start having 15 or so PACS/minute I cannot stop coughing..cannot talk. Very frustrating. I am on Metoprolol ER 2x/day

  12. Was diagnosed with PAT many yrs. ago and treated daily with Propanalol ER 60, which took care of the problem.The last several yrs. I have been periodically bothered with either PVC’s or PAC”s. I see a cardiologist about 2 times a yr. and have an echo usually yearly, have one scheduled for March before I see him. I have been having terrible PAC’c for about a week now, actually went to ER the other night due to anxiety over them. Spent a couple of hrs. on the monitor and sent home with report of PAC’s. I still have them and they are so irritating, hard to sleep and just simply function. I do have some issue with Aortic Valve that he checks with Echo. How can I get them to stop. Help!

    1. Take diltiazem. It stopped my pacs and pvcs. I was taking a beta blocker but the combination works. I only take metropolol succinate 12.5 mg at night and 30 mg diltiazem twice a day. Was worried about diltiazem side effects but it is nothing and no side effects. I was worried for nothing. They work

  13. My cardiologist just told me I may have PAC. My heart rate went from 125 when it woke me up to 216, called 911, they did an ecg and said it was sinus tacchayardia. My rhythm went down to 120 and stayed there until Sunday when I went to the DR, registered me at 150. Upon sitting it went down to 120, after fluids and beta blockers went to 95. Does this sound like PAC? This happens often.

  14. After my dentist injections stop pain for fix my teeth after 6 months now my neck still strong painful and I feel lost memory even any thing I seen but after one minute will gone ,how I taking care my neck and is that neck problems will effects memories?

  15. How do i know when to go to the hospital or not? I’ve been having bad heart palpitations which sound like PACs and severe cough episodes for three days and it’s keeping me from sleeping. When is it time to be concerned?

    1. Hi Lisa, I have lived with a PAC most of my life. I am not a doctor, but I will describe what I get. I used to feel a flutter in my heart. I would check my pulse and feel my heart stop beating then quickly start again. I would start coughing. The condition would last for a short period, about 5 to 10 minutes. And I would stop coughing. I’m retired now, but when I was working, it would magnify from stress and I would feel a lightheadedness, like passing out. The doctor put me on Beta-blockers to stop the Adrenaline flow. They worked perfectly. It was not a life threatening condition for me. Your case could be something else, so I would go see your doctor immediately. Better to be safe then sorry.

    1. I’m not sure it does and if so it is marginal. Frequent PVCs certainly can impact on the heart and cause PVC induced cardiomyopathy – which can be reversed through cessation of PVCs.

    1. Post

      Multiple PACs my result in what is called excessive supraventricular ectopic activity (ESVEA), which correlates with an increased risk of atrial fibrillation and stroke.
      Hope this helps,
      Dr T

      1. How big is the risk? Why have cardiologists repeatedly told me that frequent PVCs are more dangerous than PACs?

        Does anyone know what constitutes frequent PACs – is it greater than 500 over a 24 hour period.

        1. Your history and symptoms seem very similar to mine. I to have an issue with my Aortic Valve (leaky valve) and I’ve often wondered if my PVCS and PACs are related to the dysfunctional valve. My cardiologist says probably not but I’m not so sure.

        2. It is more like 10,000 in 24 hrs. I read that.It said 10,000 to 20,000 is excessive. I had 24,000 in one day. I’m 75. They are slowing down. Doc raised my blood pressure pill a calcium channel blocker and said if they don’t go away in a few days to call and he will give me a low dose of Metropolol.

  16. I am taking 1 pill of digoxin 250 MCG and 1 diltiazem 120 MG a day for my a fibrillation sometimes PAC come out bother me so should I need to take some more diltiazem like 60 MG please help me
    Thank you so much

    1. Post

Leave a Reply to Rose Harrison Cancel reply

Your email address will not be published. Required fields are marked *