CRT Cardiac Resynchronization QRS Threshold Calculator

Determine CRT eligibility based on QRS duration and morphology. LBBB with QRS ≥150ms: Class IA; QRS 120-149ms LBBB: Class IIa.

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Clinical Guidance

BMI is a screening measure of body size, not a direct measure of body fat. The standard WHO categories are underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥30).

BMI can overestimate body fat in athletes with high muscle mass and underestimate it in older adults with low muscle mass. Interpret it alongside waist circumference and clinical context rather than as a standalone diagnosis.

⚕ Clinical Disclaimer: These calculators are for educational and reference purposes only. Always verify results with qualified clinical judgment and current clinical guidelines. Do not use as a sole basis for medical decisions.
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How It Works

Determine CRT eligibility based on QRS duration and morphology. LBBB with QRS ≥150ms: Class IA; QRS 120-149ms LBBB: Class IIa

Each component has a specific meaning:

  • QRS duration — The qrs duration recorded for the scenario being assessed.
  • Morphology — The morphology recorded for the scenario being assessed.

Note: Interpret the crt qrs result against the thresholds and context described above.

How to Use

Enter the QRS duration, morphology for the scenario you are assessing. Determine CRT eligibility based on QRS duration and morphology. LBBB with QRS ≥150ms: Class IA; QRS 120-149ms LBBB: Class IIa. Use the crt qrs result to inform your calculation.

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