Inappropriate shock from delayed T-wave oversensing by a subcutaneous implantable cardioverter-defibrillator after septal myectomy for hypertrophic cardiomyopathy

Figures

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  Figure 1. A: A 12-lead electrocardiogram prior to septal myectomy showing sinus rhythm, left atrial enlargement, and left axis deviation with a QRS duration of 88 ms. B: A 12-lead electrocardiogram soon after septal myectomy demonstrating normal sinus rhythm, new left bundle branch block, and a QRS duration of 160 ms.

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  Figure 2. A 12-lead electrocardiogram (ECG) 39 days after septal myectomy showing sinus rhythm with left bundle branch block and a QRS duration of 154 ms. Notice the taller T waves compared to the ECG done shortly after myectomy.

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  Figure 3. Subcutaneous implantable cardioverter-defibrillator interrogation strip showing sinus tachycardia and inappropriate shock from T-wave oversensing.

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  Supplemental Figure. Panels A–C show S-ECG tracings comparing primary vector pre- and post-myectomy as well as the alternate vector following the ICD shocks. A: S-ECG at baseline (Pre-Myectomy). B: S-ECG 3 months after myectomy. C: S-ECG 2 months post-shock (sensing vector is alternate with SMARTPASS on). Note QRS axis compared to the T-wave.