Important aspects in the management of neurocardiogenic syncope

Important aspects in the management of neurocardiogenic syncope

Neurocardiogenic syncope is the most common cause of syncope. Initial measures in management include lifestyle modifications, increasing the fluid and salt intake and education about physical counterpressure methods. Pharmacological measures may be tried next. Pacemaker implantation has been tried in those with predominantly cardioinhibitory syncope [1].

Physical counterpressure measures are movements like leg crossing and hand gripping which may prevent loss of consciousness in those who feel the presyncopal symptoms. These measures increase the systemic vascular resistance and blood pressure to counter the vasodepressive element of neurocardiogenic syncope. An important limitation of physical counterpressure measures is that they can be applied by only those who have prodromal symptoms.

Important pharmacological agents which have been tried in the management of neurocardiogenic syncope are midodrine, beta blockers, paroxetine and fludrocortisone. Midodrine has been given a Class II recommendation in the management of neurocardiogenic syncope. Beta blockers may have some benefit in those above 40 years and has been given a Class IIb recommendation. But it may be harmful in those below 42 years, as noted in an analysis of the randomized Prevention of Syncope Trial (POST) [2]. POST5 is evaluating the role of metoprolol in those aged 40 years or more. It is a multicenter, international randomized placebo controlled trial [3].

Implantation of a cardiac pacemaker is considered in those with a predominant cardioinhibitory response. Pacemaker is reserved for those with severely reduced quality of life due to frequent syncope which is refractory to lifestyle changes, physical measures and medications. Pacing is planned for refractory cases above 40 years with pause more than 6 seconds with a Class IIb recommendation [4]. Closed loop stimulation is thought to be better than rate drop algorithm. SPAIN study has shown that dual chamber pacing with closed loop stimulation improves quality of life and syncope burden in patients 40 years or more with 5 or more episodes of vasovagal syncope and cardioinhibitory response induced by head up tilt testing [5].

Ablation of ganglionic plexi for the management of neurocardiogenic syncope

Cardiac vagal innervation is through ganglia in the atrial wall and epicardial fat pads. Ablation of these ganglia may also be associated with destruction of sympathetic nerve endings. But as the sympathetic ganglia situated in the sympathetic trunk are not destroyed, these nerve endings can grow back. Thus, ablation of the parasympathetic ganglia may be useful in preventing the bradycardic response in neurocardiogenic syncope. Spectral mapping and high frequency stimulation in areas known to have ganglionated plexi can be used to determine sites of radiofrequency catheter ablation. Multiple small scale studies have shown benefit. Randomized controlled clinical trials are needed to evaluate this aspect further [6].

References

1. Gampa A, Upadhyay GA. Treatment of Neurocardiogenic Syncope: From Conservative to Cutting-edge. J Innov Card Rhythm Manag. 2018 Jul 15;9(7):3221-3231. doi: 10.19102/icrm.2018.090702. PMID: 32477815; PMCID: PMC7252686.
2. Sheldon RS, Morillo CA, Klingenheben T, Krahn AD, Sheldon A, Rose MS. Age-dependent effect of β-blockers in preventing vasovagal syncope. Circ Arrhythm Electrophysiol. 2012 Oct;5(5):920-6. doi: 10.1161/CIRCEP.112.974386. Epub 2012 Sep 12. PMID: 22972872.
3. Raj SR, Faris PD, Semeniuk L, Manns B, Krahn AD, Morillo CA, Benditt DG, Sheldon RS; POST5 Investigators. Rationale for the Assessment of Metoprolol in the Prevention of Vasovagal Syncope in Aging Subjects Trial (POST5). Am Heart J. 2016 Apr;174:89-94. doi: 10.1016/j.ahj.2016.01.017. Epub 2016 Jan 25. PMID: 26995374.
4. Shen WK, Sheldon RS, Benditt DG, Cohen MI, Forman DE, Goldberger ZD, Grubb BP, Hamdan MH, Krahn AD, Link MS, Olshansky B, Raj SR, Sandhu RK, Sorajja D, Sun BC, Yancy CW. 2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients With Syncope: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2017 Aug 1;70(5):e39-e110. doi: 10.1016/j.jacc.2017.03.003. Epub 2017 Mar 9. Erratum in: J Am Coll Cardiol. 2017 Oct 17;70(16):2102-2104. PMID: 28286221.
5. Barón-Esquivias G, Moya-Mitjans A, Martinez-Alday J, Ruiz-Granell R, Lacunza-Ruiz J, Garcia-Civera R, Gutiérrez-Carretero E, Romero-Garrido R, Morillo CA. Impact of dual-chamber pacing with closed loop stimulation on quality of life in patients with recurrent reflex vasovagal syncope: results of the SPAIN study. Europace. 2020 Feb 1;22(2):314-319. doi: 10.1093/europace/euz294. PMID: 31713631.
6. Scanavacca M, Hachul D. Ganglionated Plexi Ablation to Treat Patients with Refractory Neurally Mediated Syncope and Severe Vagal-Induced Bradycardia. Arq Bras Cardiol. 2019 Jul 15;112(6):709-712. doi: 10.5935/abc.20190107. PMID: 31314822; PMCID: PMC6636377.