A 57-year-old woman presented to the emergency department with chest pain for several hours. Her past medical history consisted of dyslipidaemia, smoking, and recurrent events of palpitations with one previous event of syncope.
Admission electrocardiogram (ECG) (Figure 1A) demonstrated sinus rhythm with ST-elevation in the inferior leads. In addition, short PR interval (110 ms), right axis deviation, wide QRS complex (130 ms), positive delta waves in precordial leads V1–6, II, III, aVF, and negative delta waves in I, aVL, compatible with the presence of manifest pre-excitation due to left lateral accessory pathway (AP).
Figure 1.
The 12-lead electrocardiogram during chest pain (A) and after successful thrombolysis (B).
She was treated with successful thrombolysis and was transferred to a tertiary hospital. Electrocardiogram after the thrombolysis (Figure 1B) demonstrates sinus rhythm with normal axis, narrower QRS complex (100 ms), short PR interval, much subtle pre-excitation, and delta waves as compared with the previous ECG and normalization of the ST-elevation in the inferior leads. Note the absence of septal Q wave in V6, which supports the presence of pre-excitation, even if subtle.1
Coronary angiography showed a critical stenosis in the mid right coronary artery (RCA) that was treated with a drug-eluting stent.
An electrophysiology study demonstrated short his-ventricle (HV) interval of 35 ms consistent with pre-excitation. Due to her clinical history and a short antegrade effective refractory period of 250 ms after low-dose isoproterenol, an AP ablation using radiofrequency energy was performed successfully at the lateral mitral annulus (Figure 2A). Her ECG after the ablation is shown in Figure 2B. Ischaemia of the atrioventricular node (AVN) due to total occlusion of the mid-RCA and the AVN branch slowed conduction within the AVN or even caused complete AVN block, not a rare phenomenon in inferior wall myocardial infarction (MI).2 However, owing to the presence of a left lateral AP, the patient did not develop any type of AV block and her AP became fully manifest.
Figure 2.
(A) Electrocardiogram and intracardiac signals during ablation and atrial pacing. disappearance of pre-excitation is shown after 4.5 s of radiofrequency ablation. (B) The 12-lead electrocardiogram after ablation.
Consent: The authors confirm that written consent for submission and publication of this case report including images and associated text has been obtained from the patient in line with COPE guidance.
Conflict of interest: none declared.
References
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