Twenty-five-year-old woman with palpitations and hypertrophic cardiomyopathy ============================================================================ * Krittapoom Akrawinthawong * Vineet Kumar ## Abstract **Clinical introduction** A 25-year-old woman with a diagnosis of hypertrophic cardiomyopathy (HCM) and pre-excitation on ECG presented with unexplained syncope and daily palpitation. Genetic testing was positive for lysosome-associated membrane protein 2 (LAMP2) mutation which confirmed the diagnosis of Danon disease. Her younger sister was diagnosed with a similar condition and received a defibrillator implantation. Her 12-lead ECG (figure 1) and a long strip tracing (figure 2) are shown below. ![Figure 1](http://heartasia.bmj.com/https://heartasia.bmj.com/content/heartasia/11/1/e011174/F1.medium.gif) [Figure 1](http://heartasia.bmj.com/content/11/1/e011174/F1) Figure 1 12-lead ECG. **Question** Where is the location of the accessory pathway and what is the next appropriate management? 1. Anteroseptal pathway and catheter ablation 2. Mid-septal pathway and pacemaker/defibrillator implantation 3. Right lateral pathway and catheter ablation 4. Fasciculoventricular pathway and electrophysiological study 5. Left lateral pathway and electrophysiological study * sudden cardiac death * WPW syndrome * cardiomyopathy hypertrophic ![Figure 2](http://heartasia.bmj.com/https://heartasia.bmj.com/content/heartasia/11/1/e011174/F2.medium.gif) [Figure 2](http://heartasia.bmj.com/content/11/1/e011174/F2) Figure 2 A long strip of the ECG tracing. ## Answer: D The correct answer is fasciculoventricular (FV) pathway and electrophysiological study should be the next step of management. Figure 1 demonstrates a 12-lead ECG showing sinus rhythm with a slightly short PR interval of 112 ms and evidence of pre-excitation, especially in precordial leads. The right lateral pathway would have a negative delta wave in lead V1 and left lateral pathway would have it in lead I and aVL. Figure 2 demonstrates a junctional rhythm on the first three beats and sinus rhythm on the last three beats of tracing. There is pre-excitation present as seen by slurring in upstroke of leads V2, V3, V4, and limb leads. Of note, the degree of pre-excitation is same in the sinus and junctional beats. In a typical atrioventricular accessory pathway, junctional beats will not show any pre-excitation since the depolarisation starts below the atrium and does not engage the accessory pathway. Hence, the finding of the similar degree of pre-excitation for junctional and sinus beat is diagnostic for FV pathway. Her electrophysiological study confirmed this diagnosis with a fixed HV interval. In addition, she had easily inducible atrioventricular nodal re-entry tachycardia which most likely caused her palpitation. Successful ablation of the slow pathway was performed. A single chamber defibrillator was implanted for prevention of sudden cardiac death from HCM. FV pathway had never been demonstrated to be the key component of re-entrant tachycardia due to its short distance and considered to be benign.1 Its pre-excitation pattern could mimic anteroseptal or mid-septal pathway and lead to the unnecessary risk of complete heart block with an attempted catheter ablation. Danon disease is an X linked dominant lysosomal storage disease derived from the genetic defects in LAMP gene mutation with multiorgan involvement.2 3 Pre-excitation is very common and risk for sudden cardiac death is high3 4 in patients with Danon disease. ## Footnotes * Contributors KA and VK wrote and revised the manuscript. * Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors. * Competing interests None declared. * Patient consent for publication Not required. * Provenance and peer review Not commissioned; externally peer reviewed. This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: [http://creativecommons.org/licenses/by-nc/4.0/](http://creativecommons.org/licenses/by-nc/4.0/). ## References 1. 1. Rohrhoff NJ , Finne HA , Rodriguez Y . A sailor's dilemma: a case of preexcitation via a fasciculoventricular pathway. HeartRhythm Case Rep 2017;3:364–7.[doi:10.1016/j.hrcr.2017.05.013](http://dx.doi.org/10.1016/j.hrcr.2017.05.013) 2. 2. D'souza RS , Mestroni L , Taylor MRG . Danon disease for the cardiologist: case report and review of the literature. 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