Is a 24‑hour Holter showing PR interval 148 ms, QRS duration 141 ms, sinus rhythm with occasional sinus tachycardia up to 131 bpm, sinus bradycardia down to 51 bpm, <1 % atrial premature beats (45 total, 2 couplets) and ~1 % ventricular ectopy, in a patient with breathlessness, considered normal?

Is This 24-Hour Holter Recording Normal?

This Holter recording is abnormal and requires further evaluation, primarily due to the prolonged QRS duration (141 ms) indicating intraventricular conduction delay, which in the context of breathlessness symptoms warrants structural heart disease assessment. 1

Key Abnormal Findings

QRS Duration (141 ms)

• A QRS duration ≥120 ms is abnormal and indicates intraventricular conduction delay or bundle branch block. 2
• This finding lowers the threshold for cardiac imaging and functional studies, as conduction delay may be associated with left ventricular dysfunction. 1
• The combination of conduction delay and ventricular ectopy may indicate underlying cardiac disease requiring further investigation. 1

PR Interval (148 ms)

• The PR interval of 148 ms is normal (normal range <200 ms). 2
• First-degree AV block is only defined as PR interval >200 ms. 2

Heart Rate Variations

• Mean heart rate of 66 bpm is physiologically normal. 3
• Sinus bradycardia to 51 bpm while awake is generally benign in asymptomatic patients, as pacing is not indicated unless heart rate is chronically <40 bpm while awake or symptomatic pauses >3 seconds occur. 2, 4
• Sinus tachycardia to 131 bpm is within normal physiologic response. 3

Atrial Ectopy (<1% burden)

• 45 APBs with 2 atrial couplets and <1% burden is a very common and generally benign finding in otherwise normal hearts. 5
• Atrial ectopics are frequently found on Holter monitoring at all ages, with incidence increasing with age. 5
• In patients without structural heart disease, infrequent APBs are generally an innocent finding. 5

Ventricular Ectopy (~1% burden)

• 194 VPCs with 1% burden can occur in apparently healthy subjects and may be benign if ventricular function is normal. 6
• However, the presence of conduction delay alongside VPCs mandates echocardiographic evaluation to exclude cardiomyopathy. 1

Critical Symptom Correlation

The patient's episodes of breathlessness occurring during sinus rhythm (67-84 bpm) suggest the symptoms are NOT directly caused by bradyarrhythmia. 2

• Symptomatic bradycardia is defined as documented bradyarrhythmia directly responsible for syncope, presyncope, dizziness, heart failure symptoms, or confusional states from cerebral hypoperfusion. 2
• Since breathlessness occurred at normal heart rates (67-84 bpm), this excludes a primary bradycardic etiology. 2
• The breathlessness may be related to underlying structural heart disease, particularly given the conduction abnormality. 1

Mandatory Next Steps

Immediate Evaluation Required

• Echocardiography is strongly recommended as the first diagnostic test to assess for structural heart disease and left ventricular function. 1, 4
• Exercise stress testing should be considered to evaluate chronotropic competence and assess whether conduction abnormalities worsen with activity. 1, 4
• Cardiac MRI may be considered if echocardiography is normal but clinical suspicion for structural disease remains high. 1

Exclude Secondary Causes

• Thyroid function tests should be performed, particularly important with wide heart rate variations. 3
• Review all medications that may affect conduction (beta-blockers, calcium channel blockers, digoxin). 4

Management Algorithm

If Echocardiogram Shows Normal Structure and Function:

• Reassurance regarding the atrial and ventricular ectopy is appropriate. 1, 6
• The conduction delay still requires regular follow-up every 6-12 months to monitor for progression. 4
• Investigate alternative causes of breathlessness (pulmonary, deconditioning, anxiety). 1

If Structural Heart Disease or Ventricular Dysfunction Identified:

• Beta-blockers are first-line therapy for symptom control and reduction of VPC burden. 1
• More aggressive evaluation and treatment based on specific findings. 1
• Consider electrophysiology study if conduction disease progression is suspected. 1, 4

Critical Pitfalls to Avoid

• Do not dismiss the QRS prolongation as benign without structural assessment. 1
• Do not attribute breathlessness to the minimal ectopy burden without excluding other causes. 4
• Do not overlook the possibility that conduction delay may progress to higher-grade block. 4
• Avoid medications that further slow AV conduction unless specifically indicated. 4