Radiofrequency Catheter Ablation of the Accessory Pathway Adversely Affected the Left Ventricular Outflow Tract Pressure Gradient in a Patient With Hypertrophic Obstructive Cardiomyopathy

Abstract

SummaryAlthough hypertrophic cardiomyopathy (HCM) with an accessory pathway is encountered in clinical practice, there is little evidence of a coherent strategy for ablation of the accessory pathway in patients with HCM. We present the case of a 61-year-old man who had type B Wolff-Parkinson-White (WPW) syndrome with hypertrophic obstructive cardiomyopathy (HOCM). Due to paroxysmal atrial fibrillation, he underwent radiofrequency catheter ablation of the accessory pathway located in the right postero-lateral wall to prevent secondary symptomatic events. His LV dyssynchrony improved after the procedure, but the degree of the LV outflow tract (LVOT) pressure gradient was increased. To stabilize the LVOT pressure gradient, he needed additional medications. This case shows that patients with HOCM should be carefully evaluated before making a decision concerning ablation of the accessory pathway. ( 1,2) Radiofrequency catheter ablation (RFA) of the accessory pathway is acceptable first-time therapy for symptomatic WPW syndrome. On the other hand, hypertrophic obstructive cardiomyopathy (HOCM), which is characterized by LV outflow obstruction due to hypertrophy, predisposes the patients to hemodynamic collapse and thereby to a severe LV outflow tract (LVOT) pressure gradient.3) Although a previous report showed that 5% of patients with hypertrophic cardiomyopathy (HCM) had ventricular pre-excitation, the comorbidity of WPW syndrome and HOCM is rarely encountered in clinical practice.4) Patients with HOCM, generally, should be controlled with relative bradycardia, because the LV diastolic volume will be relatively increased and, accordingly, the LVOT pressure gradient will be relieved. In this regard, if they have an accessory pathway and experience AF, RFA is recommended for suppression of tachyarrhythmia. However, while deletion of the accessory pathway improves LV dyssynchrony, it may adversely affect the LVOT pressure gradient. There are some reports showing that the pressure gradient of HOCM is ameliorated by dual chamber pacing with short atrioventricular delay, which leads to LV dyssynchronous contraction. 5,6) In this regard, LV dyssynchrony might be required to relieve the LVOT pressure gradient of HOCM. We present a patient with both WPW syndrome and HOCM in whom the LVOT pressure gradient was affected by RFA. Case ReportA 61-year-old man with no remarkable past medical history was brought to our hospital because of a pre-syncopal episode. He had felt chest discomfort and faintness about 30 minutes after lunch. His vital signs were stable and the symptoms had disappeared at the time of consultation. On physical examination, a systolic murmur was maximally audible from the middle left sternal border. There was no pitting edema in the lower extremities, and no abnormality in the neurological findings. Although most of his laboratory data were normal, his blood level of B-type natriuretic peptide (BNP) was high (325 pg/mL). A 12-lead electrocardiogram (ECG) showed a profound high-voltage of R wave (S wave in V1 ...