What really causes an irregular heartbeat and when to worry

By Sina Hartung, MMSC-BMI, Harvard Medical SchoolReviewed by Eureka Health Medical Group
Published: July 9, 2025Updated: July 9, 2025

Summary

An irregular heartbeat happens when the heart’s electrical system mis-fires. The most common culprits are atrial fibrillation from age-related wear, coronary artery disease, high blood pressure, thyroid or electrolyte problems, certain medicines, and stimulants like caffeine or cocaine. Pinpointing the exact cause requires a physical exam, ECG, and lab work, because some rhythm problems are harmless flutters while others predict stroke or sudden cardiac arrest.

What is the single biggest cause of an irregular heartbeat?

Most irregular heartbeats start with a disturbance in the atria, the heart’s upper chambers. Ageing tissue, high blood pressure, and structural changes allow abnormal electrical loops—especially atrial fibrillation—to develop.

  • Atrial fibrillation drives 60 % of clinically significant arrhythmiasMore than 5 million Americans live with atrial fibrillation (AF); by 2030 that number is projected to double. AF causes the atria to quiver instead of contract, producing an irregular, often rapid pulse. “AF is the rhythm problem we look for first because it carries a five-fold stroke risk,” notes the team at Eureka Health.
  • Coronary artery disease injures the heart’s wiringBlocked arteries deprive cells of oxygen, leading to scar tissue that disrupts electrical flow. Post-heart-attack patients have a 20-30 % lifetime risk of ventricular arrhythmias.
  • Overactive or underactive thyroid shifts heart rateToo much thyroid hormone can push the heart above 120 beats per minute at rest; too little can create long pauses. A simple TSH blood test often uncovers the problem.
  • Electrolyte imbalances alter the heart’s voltageLow potassium, magnesium, or calcium change how fast electrical signals travel. Hospital data show hypokalemia triggers premature ventricular beats in up to 40 % of emergency admissions.
  • Stimulants and certain drugs provoke ectopic beatsExcess caffeine, decongestants, beta-agonist inhalers, or street stimulants like cocaine can all spark palpitations within minutes. “Even so-called natural supplements that raise adrenaline can destabilize the rhythm,” warns Sina Hartung, MMSC-BMI.
  • High blood pressure is the leading medical condition behind AFThe NIH lists hypertension as the most common underlying change that damages atrial tissue and disrupts normal signaling, laying the groundwork for an irregular heartbeat. (NIH)
  • Risk climbs sharply after age 60The Texas Heart Institute notes that advancing age—particularly beyond 60 years—is the single biggest risk factor for developing atrial fibrillation and other irregular rhythms. (THI)

Which red-flag symptoms mean an irregular heartbeat is dangerous?

Most skipped beats are benign, but specific signs point to a life-threatening arrhythmia or an underlying heart attack.

  • Chest pressure or pain alongside palpitationsCombined symptoms raise the likelihood of myocardial ischemia; one emergency study found 1 in 8 patients with both signs had an acute coronary syndrome.
  • Dizziness or near-fainting with heart rates above 150Sustained rapid rates starve the brain of blood. “Any arrhythmia that makes you light-headed warrants immediate ECG monitoring,” states the team at Eureka Health.
  • Episodes lasting longer than 30 minutesPersistent irregularity increases the risk of clot formation and should be treated as an emergency, especially in older adults.
  • Shortness of breath that worsens when lying flatCould indicate new-onset heart failure caused by the arrhythmia itself.
  • Sudden collapse or full faintSyncope can signal ventricular tachycardia, which has a 10 % out-of-hospital survival rate if untreated.
  • Sudden stroke-like symptoms during palpitationsAny irregular heartbeat that is followed by slurred speech, facial droop, or arm weakness can signal a clot has already reached the brain; Atlantic Cardiovascular lists these neurologic changes as 911-level emergencies. (AtlanticCV)
  • Profuse sweating or cold, clammy skin with an irregular rhythmAurora Health Care includes unexplained sweating alongside chest pain and shortness of breath as reasons to seek immediate evaluation, because they often accompany serious ischemia or fast ventricular rhythms. (AuroraHC)

What everyday triggers should you avoid to keep your rhythm steady?

Certain habits and exposures make the heart’s electrical cells more irritable. Knowing and limiting these triggers can prevent many palpitation episodes.

  • High-dose caffeine above 400 mg per dayThat equals about four 8-oz coffees. Research shows a 14 % rise in premature beats at this intake level.
  • Binge drinking, even just on weekendsHoliday Heart Syndrome—AF that appears after heavy drinking—accounts for 5 % of all new AF cases during festive seasons, says Sina Hartung, MMSC-BMI.
  • Insomnia and obstructive sleep apneaInterrupted sleep raises nighttime adrenaline and doubles the risk of AF compared to normal sleepers.
  • Large, salty mealsSudden fluid shifts stretch the atria, triggering extrasystoles, especially in people with hypertension.
  • Energy drinks and weight-loss supplementsMany contain synephrine or high caffeine doses, both linked to dangerous QT prolongation.
  • Nicotine—from cigarettes or e-cigs—provokes arrhythmiaHealthgrades reports that nicotine not only spikes blood pressure but also worsens atrial fibrillation and increases stroke risk, so steering clear of tobacco products helps keep the heartbeat regular. (Healthgrades)
  • Dehydration shifts electrolytes and sparks AF episodesVA Arrhythmia Consultants explain that even mild fluid loss can disturb sodium-potassium balance, an often-missed trigger that can set off palpitations. (VA)

Which self-care steps can you take during a flutter episode?

Simple physical maneuvers and monitoring can settle certain arrhythmias while you arrange professional care.

  • Vagal maneuvers such as a firm coughActivating the vagus nerve can slow supraventricular tachycardia (SVT) in up to 25 % of cases, according to emergency department audits.
  • Ice-cold face immersion for 10–15 secondsThe diving-reflex often resets paroxysmal SVT. “Always do this seated to avoid fainting,” advises the team at Eureka Health.
  • Use a smartphone ECG or pulse oximeterCapturing a 30-second strip helps doctors confirm the rhythm; devices like KardiaMobile are FDA-cleared for AF detection.
  • Hydrate with a glass of water or oral rehydration saltsCorrecting mild dehydration can normalize premature beats caused by low blood volume.
  • Practice slow diaphragmatic breathingSix breaths per minute activates parasympathetic tone and may lower heart rate by 5–10 bpm within five minutes.
  • Cut out caffeine, nicotine, and other stimulantsHealthgrades lists stimulants as frequent palpitation triggers and notes that avoiding caffeine, nicotine, heavy alcohol, some cold medicines, and illicit drugs can let the rhythm settle quickly: “Steer clear of stimulants such as caffeine, nicotine, heavy alcohol use, certain medications, and illegal drugs.” (HG)
  • Replenish electrolytes with potassium-rich snacksLow potassium or magnesium can provoke extra beats; Healthline advises drinking water and eating foods like bananas, avocados, spinach, and potatoes to restore “potassium, calcium, magnesium, and sodium” balance that supports steady conduction. (HL)

What lab tests and medications are most relevant to irregular heartbeats?

Diagnosis begins with a 12-lead ECG, but blood work and appropriate drug therapy determine long-term outcomes.

  • Electrolyte panel and renal functionDetects low potassium or magnesium. Correcting these abnormalities cuts ventricular ectopy by 50 % in hospitalized patients.
  • TSH and free T4 levelsGuidelines suggest checking thyroid function in all new AF cases. “Treating hyperthyroidism often restores normal rhythm without lifelong drugs,” notes Sina Hartung, MMSC-BMI.
  • High-sensitivity troponinElevations can reveal silent heart muscle injury prompting urgent coronary evaluation.
  • Rate-control medicines (beta-blockers, calcium-channel blockers)Often first-line to keep the pulse under 110 bpm. Your clinician will individualize choice based on blood pressure and lung function.
  • Anticoagulation decisions guided by CHA₂DS₂-VASc scoreEach 1-point rise increases annual stroke risk by about 1 %. The score informs whether blood-thinning medication is needed.
  • Medication review for QT-prolonging agents is essentialThe American Heart Association notes that older adults, patients with prior heart disease, or those with low potassium or magnesium are at heightened risk for drug-induced arrhythmias from agents such as certain antibiotics, antipsychotics, and cancer therapies, so prescriptions should be reassessed whenever an irregular heartbeat is detected. (AHA)
  • 24-hour Holter monitoring captures intermittent arrhythmias missed on office ECGBangkok Heart Hospital recommends ambulatory ECG monitoring for 24–48 hours to document paroxysmal rhythm disturbances that a single 12-lead ECG may overlook, leading to more accurate diagnosis and targeted treatment. (BHH)

How can Eureka’s AI doctor help you during a palpitation episode?

Eureka’s AI doctor can triage your symptoms in real time, guiding you on whether to call 911, visit urgent care, or use self-care maneuvers first.

  • Symptom-based risk stratification in under 60 secondsYou enter chest pain, pulse rate, and dizziness; the algorithm compares them with guideline thresholds and explains the next safest step.
  • On-demand ECG interpretationUpload a photo of your smartwatch ECG, and Eureka highlights AF, pauses, or prolonged QT. “Users appreciate the immediate, plain-English summary,” says the team at Eureka Health.
  • Instant lifestyle trigger checklistThe app generates a personalized list—sleep, alcohol, caffeine—ranked by likelihood of causing your episode.
  • Secure chat with a physician within two hours if high-riskIf the AI flags danger, it forwards your data to our on-call cardiology team for rapid review and instructions.

What ongoing rhythm care can Eureka provide after the crisis?

Eureka is more than a triage tool. It supports chronic management so that irregular heartbeats become less frequent and less scary.

  • Automated reminders for labs and follow-up ECGsMissed monitoring is cut by 35 % among active users, based on internal analytics.
  • Medication adherence tracking with safe refill requestsIf you forget doses or run low, the AI prompts you and can route a refill request to our medical team for review.
  • Customized exercise and sodium targetsGoals adjust using your weekly weight and blood-pressure logs. “Small behavior nudges lower resting heart rate by about 4 bpm over three months,” reports the team at Eureka Health.
  • Anonymous community support rated 4.8 / 5 by users with AFSharing coping tips reduces anxiety—a known trigger for palpitations.
  • Private, HIPAA-compliant data vaultAll ECGs, labs, and chat transcripts stay encrypted; only you and the reviewing clinician can see them.

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Frequently Asked Questions

Can dehydration alone cause an irregular heartbeat?

Yes. Low blood volume concentrates electrolytes and activates stress hormones, leading to premature beats, especially in hot weather or during intense exercise.

Is an occasional skipped beat after coffee dangerous?

One or two isolated ectopic beats are usually harmless. Persistent or worsening palpitations after caffeine should prompt you to cut back and get an ECG.

How long should I try vagal maneuvers before calling 911?

If the rapid, irregular heartbeat lasts more than 15 minutes or causes chest pain, dizziness, or shortness of breath, seek emergency care regardless of maneuvers.

Does magnesium really help prevent arrhythmias?

Only if you are deficient. Blood levels below 1.7 mg/dL can trigger irregular beats; correcting them with oral supplements or IV therapy reduces episodes.

Can stress alone trigger atrial fibrillation?

High stress raises adrenaline and cortisol, which can precipitate AF in susceptible hearts, but it rarely acts alone—structural heart changes are usually present too.

Are wearable ECG watches accurate for diagnosing AF?

FDA-cleared devices like Apple Watch Series 4 or later have a sensitivity around 98 % for AF in clinical studies, but they cannot detect every arrhythmia.

Will I need blood thinners forever if I have AF?

It depends on your stroke-risk score (CHA₂DS₂-VASc). Low-risk patients may avoid long-term anticoagulation; your doctor will reassess yearly.

Can I exercise with an irregular heartbeat?

Light to moderate activity is often safe and beneficial, but uncontrolled fast rhythms or structural heart disease require medical clearance first.

How often should thyroid tests be repeated after correcting hyperthyroidism?

During the first year, guidelines suggest every 6-12 weeks until stable, then every 6-12 months unless symptoms recur.

Does Eureka share my data with insurance companies?

No. Eureka stores your data in an encrypted environment and does not sell or share it with insurers or advertisers.

This content is for informational purposes only and is not intended as medical advice. Always consult with a qualified healthcare provider for diagnosis, treatment, and personalized medical recommendations.

General References