SPC365

Front-loaded head-up tilt table testing for the diagnosis of reflex syncope

Session: CO 11- Síncope
Speaker: Catarina de Oliveira

Congress: CPC 2021
Topic: C. Arrhythmias and Device Therapy
Theme: 07. Syncope and Bradycardia
Subtheme: 07.3 Syncope and Bradycardia - Diagnostic Methods
Session Type: Comunicações Orais
FP Number: ---
Authors: Catarina De Oliveira; Helena Da Fonseca; Sérgio Laranjo; Pedro Silva Cunha; Madalena Coutinho Cruz; Bruno Valente; Guilherme Portugal; Rui Cruz Ferreira; Mário Martins Oliveira
<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong><span style="font-size:10.0pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><span style="color:black">Introduction: </span></span></span></strong><span style="font-size:10.0pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><span style="color:black">Head-up tilt testing (HUT) is commonly used for the diagnosis of reflex syncope, with various protocols applied in the last two decades. Currently, it is a labour intensive and time-consuming method, particularly in the present COVID-19 pandemic. The front-loaded (FL) protocol has been suggested as a rapid alternative to conventional &ldquo;passive&rdquo; protocol option, with the potential to provide a higher diagnostic. Our aim was to compare the clinical, hemodynamic and autonomic results of the FL HUT and the modified Italian protocol (IP) in patients (P) with reflex syncope.</span></span></span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong><span style="font-size:10.0pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><span style="color:black">Methods: </span></span></span></strong><span style="font-size:10.0pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><span style="color:black">165 consecutive P with unexplained recurrent syncope were submitted to HUT from September 2019 to December 2020. The modified IP was applied in 88 P (53%), and 77 P (47%) were assigned to the FL protocol. Briefly, in the IP, there was a supine stabilization phase of 20 min, followed by a 20 min passive phase at 70 degrees tilt angle and a provocation phase of further 20 min (after 500 &mu;g sublingual nitroglycerin [NTG]). In the FL the supine phase was of 10 min, followed by administration of 500 &mu;g NTG and 20 min at a tilt angle of 70 degrees. Positive responses were classified according to the modified Vasovagal Syncope International Study (VASIS) classification. All P were continuously monitored for blood pressure, ECG, stroke volume (SV), cardiac output (CO), total peripheral resistance (TPR) and autonomic variables using a TaskForce monitor (CNSystems, Graz, Austria).</span></span></span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong><span style="font-size:10.0pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><span style="color:black">Results: </span></span></span></strong><span style="font-size:10.0pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><span style="color:black">In both protocols, P were divided in 2 groups according to NTG response: &quot;fainters&quot; (HUT[+]) and &quot;non fainters&quot;(HUT[-]). In the IP 73% (n=64) were fainters (23% type 1, 9% type 2A, 16% type 2B, 52% type 3). In comparison, in FL 45% (n=35) fainted (14% type 1, 9% type 2A, 20% type 2B, 57% type 3). After NTG the hemodynamic and autonomic responses were similar for both protocols: SV, CO and TPR decreased progressively, together with HR increase, but with statistical significance only for HUT[+]. Moreover, BP was stable during a short period, after which a progressive and significant decrease was observed till syncope. In HUT[-], BP, despite slightly lower, was not significantly different from the values of the drug-free period. HUT[+] had a significant rise of sympathetic activity, followed by a continuous steep decrease (to levels below drug-free period) towards syncope; whereas HUT[-] showed a mild, yet significant, increase in sympathetic activity. Baroreflex sensitivity decreased after NTG in all P, but significance was found only for HUT[+].</span></span></span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong><span style="font-size:10.0pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><span style="color:black">Conclusion: </span></span></span></strong><span style="font-size:10.0pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><span style="color:black">The FL protocol proved to be an effective, faster, alternative for HUT. The mechanisms underlying the protocol are similar between different protocols. This fact supports the benefit of its use, namely during pandemic, where contacts with patients should be reduced to the essential minimum.</span></span></span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong><span style="font-size:10.0pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><span style="color:black">Keywords:</span></span></span></strong><span style="font-size:10.0pt"><span style="font-family:&quot;Times New Roman&quot;,serif"><span style="color:black"> Reflex syncope, head-up tilt testing, front-loaded protocol</span></span></span></span></span></p>