Support
Support
Search

See Beyond Symptoms

A new publication in Heart Rhythm examines the relationship of symptom frequency and symptom-rhythm correlation to arrhythmia type and detection. Short-term (24–48 hour) monitoring, such as Holter monitoring, may miss clinically actionable events — even in patients with frequent or daily symptoms.1

Download the summary
A photo of a physician speaking with a patient.
More than 1.1 M patients analyzed
1,100,377 patients wearing Zio long-term continuous monitors (Zio LTCM which includes Zio XT and Zio monitor) with a wear duration ≥ 7 days were analyzed.*†

* Included patients ≥ 18 years of age.

† Cases of Permanent/Persistent Atrial Fibrillation (defined as burden ≥ 85%) were excluded.

Daily vs non-daily symptoms
229,005 patients with daily symptoms (≥ 1 button press per day).
871,332 patients with non-daily symptoms (< 1 button press per day).
Outcomes evaluated
Arrhythmia yield*

Time to first episode
Symptom-rhythm correlation2

* Total arrhythmia yield is the proportion of patients with AF or Aflutter of ≥ 30 seconds, SVT of ≥ 90 bpm & ≥ 4 beats, sustained SVT of ≥ 90 bpm and ≥ 30 seconds, VT of ≥ 100 bpm and ≥ 4 beats, any VF, pause of ≥ 3 seconds, and AVB (any second-degree or complete heart block).

Key takeaways1,2

  • 35.8% of patients had an actionable arrhythmia detected within the ≤ 14-day wear period.
  • In patients with frequent button presses, 64% of arrhythmias appear after 48 hours — beyond the window of short-term monitoring, which may miss clinically meaningful events.
  • Whether patients feel symptoms daily or rarely has no to little bearing on when arrhythmias were detected.
  • Only 18% of arrhythmias were aligned with a symptom — many arrhythmias occur silently and are not associated with symptoms.

Actionable arrhythmia yield

A graphic showing 35.8% in a circle with a blue background.
Any actionable arrhythmia detected through the ≤ 14-day period.

Actionable arrhythmia yield criteria, except excludes SVT < 30s

In patients with frequent button presses

A graphic showing 2 in 3 in a circle with a blue background.
Actionable arrhythmias were detected after the first 48 hours.

Symptom-rhythm correlation

A graphic showing 1 in 5 in a circle with a blue background.
Patients had a documented symptom-rhythm correlation, despite frequent button presses.
Explore the full publication
Review methodology, results, and clinical implications.
Read the publication

Symptoms don’t reliably predict arrhythmias

Symptoms such as palpitations, dizziness, and fainting are typical but often unpredictable and transient. Patients with frequent symptoms were not more likely to have earlier arrhythmia detection. Longer-term monitoring may improve diagnostic yield.1

A photo of a physician speaking with a patient.

Symptoms can be misleading

Many conditions present with symptoms similar to those of cardiac arrhythmia, making symptom-rhythm correlation important for accurate diagnosis.3

Anxiety / Panic Attacks4
Rapid heart beat, palpitations, chest pain/tightness, shortness of breath, dizziness, sweating, trembling

Low Blood Sugar (Hypoglycemia)5
Palpitations, shakiness, dizziness/light-headedness, sweating, irritability

Gastroesophageal Reflux (GERD)6
Chest discomfort/pain, chest tightness, palpitations

Thyroid Disorders7
Rapid or irregular heartbeat, palpitations, fatigue, nervousness

Low Blood Pressure8
Dizziness/light-headedness, fatigue

Pulmonary and Other Non-Cardiac Chest Pain Causes9
Chest pain/discomfort, shortness of breath

Symptom-rhythm correlation was low, occurring in less than 20% of patients with arrhythmias1,2

All patients

Daily symptoms

Non-daily symptoms1,2

Patients may struggle to self-identify arrhythmias based on symptoms

Arrhythmias are often asymptomatic.

 

Symptoms can point to many conditions, not just arrhythmias. 14-day monitoring helps reveal what’s happening.

Most actionable arrhythmias were detected beyond 48 hours1

Frequent symptoms may not be a good proxy for selection of monitoring duration, and clinically meaningful events may be missed beyond the standard 48-hour monitoring window. 14-day monitoring may help capture arrhythmias that short-term monitoring can miss.

Across most arrhythmia types, the median time to detection exceeded 48 hours

Median time to actionable arrhythmia detection was 3.5 days in patients with daily symptoms vs 3.0 days in patients with non-daily symptoms.


Median detection times for paused supraventricular tachycardia (SVT), ventricular tachycardia (VT), and atrioventricular block (AVB) ranged from 2.4 to 6.0 days.

Clinical and healthcare system implications

Implications for clinicians
  • Short-term monitoring may provide a false sense of security.
  • Symptom frequency alone does not predict when arrhythmias will be detected.1
  • Even patients with frequent symptoms may not have their first arrhythmia detected until several days into monitoring.1
  • Given the subjectivity of patient-reported symptoms, long-term objective monitoring enables accurate linkage of symptoms to arrhythmias.1,2
Implications for healthcare systems
  • Across two large real-world studies CAMELOT and AVALON, Zio LTCM service has been studied in more than 700,000 diagnostic-naïve patients.
  • Compared to short-term monitoring (up to 48 hours), Zio LTCM service was associated with higher diagnostic yield and lower likelihood of a retest.10-15
  • Monitoring strategy can also influence downstream care, enabling clinicians to develop more effective treatment plans to prevent hospitalization.10-16
A graphic of the My Zio app

Benefits of using the MyZio mobile app

Patients using the MyZio app were 4.3x more likely to record at least one symptom during an arrhythmia compared to patients using a paper log booklet.17

Encourage your patients to use MyZio symptom tracking app to log symptoms, receive timely notifications and get answers to their questions right at their fingertips.


Download the app today on iOS or Android.

Download on App Store
Download on Google Play
Continue the conversation
Man with child on his shoulders
 
  1. Battisti et al. Relationship of Symptom Frequency and Symptom-Rhythm Correlation to Arrhythmia Type and Time to Detection: Insights from Ambulatory ECG Monitoring in Over 1 Million Patients. Heart Rhythm. 2025;S1547-5271(25)03049-8.
  2. The Zio ECG monitor is intended to capture symptomatic and asymptomatic cardiac events in a continuous electrocardiogram record for (up to 14 days of) long-term monitoring.  Preliminary findings in the Zio report are intended to be used by clinicians as an aid in arrhythmia diagnosis and management. The prescribing healthcare professional is responsible for determining the clinical relevance of any symptoms in relation to arrhythmia findings.
  3. Steinberg et al. 2017 ISHNE-HRS expert consensus statement on ambulatory ECG and external cardiac monitoring/telemetry. Heart Rhythm. 2017;14(7):e55-e96.
  4. Frommeyer et al. Panic attacks and supraventricular tachycardias: the chicken or the egg? Neth Heart J. 2013;21(2):74-7.
  5. American Diabetes Association. “Signs, Symptoms and Treatment for Hypoglycemia (low blood glucose)” https://diabetes.org/living-with-diabetes/hypoglycemia-low-blood-glucose/symptoms-treatment. Accessed June 18, 2026.
  6.  Fass et al. Noncardiac chest pain: epidemiology, natural course and pathogenesis. J Neurogastroenterol Motil. 2011;17(2):110-23.
  7. Web MD, “What’s the Link Between Afib and Thyroid Disease?” https://www.webmd.com/heart-disease/atrial-fibrillation/afib-thyroid-disease-link. Accessed June 18, 2026.
  8. Web MD Website. “Conditions that look like Afib”. https://www.webmd.com/heart-disease/atrial-fibrillation/conditions-that-look-like-afib. Accessed June 18, 2026.
  9. Michigan University Health. “When chest pain isn’t a heart attack.” https://www.michiganmedicine.org/health-lab/when-chest-pain-isnt-heart-attack Accessed June 18, 2026.
  10. Russo et al. Assessment of variation in ambulatory cardiac monitoring among commercially insured patients. Am J Manag Care. 2026;32(2):65-73.
  11. Reynolds MR, et al. Comparative effectiveness and healthcare utilization for ambulatory cardiac monitoring strategies in Medicare beneficiaries. Am Heart J. 2024;269:25-34.
  12. The Zio LTCM service facilitates a diagnosis as determined by a physician.
  13. In AVALON, Arrhythmias were defined by a panel of clinical experts and study investigators. In CAMELOT, a specified arrhythmia refers to an arrhythmia encounter diagnosis as per Hierarchical Condition Categories (HCC) 96.
  14. The study is based on the previous generation Zio XT device data. The devices used in the Zio LTCM monitoring service are deemed substantially equivalent. Additional data on file.
  15. Zio LTCM service refers to Zio XT and Zio monitor service.
  16. Hendrickson et al. Cardiac Ambulatory Monitoring and Hospital Quality (CAMELOT IQ): Strategies for Reducing Length of Stay and Readmissions. J Health Med. 2025. Published online Sept 29, 2025. DOI:10.36648/ipctn.11.1.150.
  17. iRhythm Data on File, 2024.

MAT-0030-1