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ECG Findings

  • High-voltage QRS suggesting LVH

  • Deep, narrow, “dagger-like” Q waves, especially in the lateral (V5, V6, I, aVL) and inferior (I, III ,aVF) leads

  • Deep S waves in anterior precordial leads

  • Lateral T-wave inversions


  1. Hypertrophic obstructive cardiomyopathy (HOCM) causes hypertrophy of the interventricular septum, causing outflow obstruction, and predisposes the patient to ventricular arrhythmias.

  2. Always consider this condition in young athletes with syncope or severe dyspnea on exertion.

  3. The Q waves seen in HOCM can be mistaken for Q waves seen in myocardial ischemia; however, infarction Q waves are typically > 40 ms, whereas HOCM Q waves are < 40 ms.


Hypertrophic Cardiomyopathy with Underlying Atrial Flutter with 2:1 Block. (ECG contributor: James V. Ritchie, MD.)


Deep S-wave voltage (28 mm S in V2, large arrow) and narrow Q waves in V5 and V6 (arrowheads). This patient also has atrial flutter with 2:1 block. The additional P waves appear in the ST segments (small arrows).

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