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Supraventricular tachycardia: REVERT trial

Andrew Appelboam FRCEM
12 May, 2016  

This article outlines a recent randomised controlled trial of a modified Valsalva manoeuvre for the treatment of supraventricular tachycardia

Andrew Appelboam FRCEM
Adam Reuben FRCEM
Department of Emergency Medicine, Royal Devon and Exeter Hospital NHS Foundation Trust, Exeter
Clifford Mann FRCEM
James Gagg FRCEM
Department of Emergency Medicine, Musgrove Park Hospital, Taunton & Somerset NHS Foundation Trust
Paul Ewings PhD
NIHR Research Design Service South West, University of Exeter Medical School
Andrew Barton MSc
NIHR Research Design Service South West, Plymouth University Peninsula Schools of Medicine and Dentistry
Trudie Lobban MBE FRCP
Arrhythmia Alliance, Stratford-upon-Avon
Mark Dayer FRCP
Department of Cardiology, Musgrove Park Hospital, Taunton & Somerset NHS Foundation Trust
Jane Vickery MSc
Peninsula Clinical Trials Unit, Plymouth University
Jonathan Benger MD 
Faculty of Health and Life Sciences, University of the West of England, Bristol
Email: andy.appelboam@nhs.net
 
Supraventricular tachycardia (SVT) is a group of commonly occurring heart rhythm disorders including re-entrant tachycardia, with an estimated incidence of 35 episodes per 100,000 persons per year.1 Episodes often affect healthy individuals, causing attacks of rapid heart rates and palpitations that are unpleasant and disruptive to patients’ lives.2,3 Patients often seek medical help during attacks and annually about 50,000 patients attend an emergency department (ED) in the USA with SVT.4
 
The Valsalva manoeuvre (VM) is a very safe and internationally recommended physical treatment for SVT that has been in use for over 100 years.5,6 The manoeuvre involves a forced exhalation or strain against resistance (like blowing up a balloon) and causes a reflex slowing of the heart, which can return (cardiovert) the heart rhythm to normal during an attack of SVT. 
 
However, the VM has a relatively low (5–20%) cardioversion success rate in clinical practice7,8 and patients who remain in SVT are usually treated with intravenous adenosine. Whilst effective, this drug causes a transient pause in all cardiac activity and this can be associated with unpleasant side effects that many patients find frightening. Some patients even report they feel they are about to die and significant adverse events have been reported.2,9 Other treatments, such as DC cardioversion are invasive and also not without risk.10,11
 
The VM might be improved by postural changes designed to increase venous return just after the strain.10,12,13 Improving the VM would reduce the number of patients who need to go on to have adenosine treatment in hospital and could prevent the need to attend at all if successfully employed in the community. 
 
Photo credit: Plymouth University.
 
The REVERT trial was a randomised controlled trial (ISRCTN67937027) to see if a simple, cost-free postural modification to the standard VM could improve VM effectiveness and reduce the number of patients who need to undergo further emergency treatment including adenosine.14
 
In this study more than 400 stable adult patients attending emergency departments in England with an attack of SVT were randomised to a standard (control) VM strain, (performed in a semi-recumbent position) or to a modified VM, performed in the same semi-recumbent position but with participants repositioned immediately at the end of the strain period to supine with their legs passively raised to 45 degrees for 15 seconds. Both groups used a standardised Valsalva strain (40mmHg pressure for 15 seconds) using a manometer. 
 
Analysis was conducted blind to treatment allocation and on an intention to treat basis. Those assigned to the standard VM had a cardioversion rate of 17% whereas 43% of those allocated to the modified VM were returned to sinus rhythm at one minute post-VM, confirmed on a 12-lead ECG. This difference was highly significant with an odds ratio (95% confidence interval) of 3.7 (2.3–5.8), p<0.0001 (see Table 1).
 
 
This was associated with a significant reduction in the use of adenosine and other emergency treatments in the modified VM group. In fact, in this study fewer than three patients with SVT needed to be treated with a modified VM to prevent the use of any further emergency treatment during that attendance. When patients who had been recruited with an ineligible heart rhythm (protocol violations) and those who had spontaneous cardioversion prior to VM were excluded (per protocol anaysis), the modified VM was even better with 47% of patients cardioverting.
 
There were no serious adverse events reported for either group and no significant difference in non-serious adverse events that were rare, minor and self-limiting.
 
This study was pragmatic and conducted in an environment in which these patients are usually treated, but utilised a modification that can be undertaken in other environments including outside of medical facilities and without specialist equipment. Although the trial used a manometer to ensure a consistent and measurable strain pressure between the groups, a 10ml syringe blown to just move the plunger equates to the pressure used in the study.15 The proposed modification to the VM does not interfere with or replace specialist treatment such as accessory pathway radiofrequency ablation.
 
Treating clinicians were not blinded to the study treatments but allocation concealment was used and standardised instructions disguised from participants which allocation was the study intervention and which was the control. Strain data also showed there was no evidence of a difference in effort of the VM strain between the groups.
 
A cost-free, modified VM that can be performed without specialist drugs or equipment with a success rate approaching 50%, has major potential benefits for patients who suffer from SVT. If patients can safely undertake a Valsalva strain and be repositioned as described, routine use of this manoeuvre could save a large number of patients around the world the need to be treated with adenosine (the study suggests a 20% absolute reduction) or other emergency treatments and even negate the need to come to hospital, if sucessfully employed at home or in the pre-hospital setting. Clinicians, pre-hospital practitioners and hospital staff who treat SVT as well as their patients should learn and employ this technique.
 
The challenge now is the dissemination of the findings of this study, ensuring the routine use of the technique and evaluation of its efficacy in routine practice. Only by doing so can we ensure patients and healthcare providers benefit from this simple and cost-free treatment.
 
Conclusion
In stable adult patients undergoing a VM to treat an attack of SVT, a modified technique using leg elevation and supine positioning at the end of the strain phase is safe, much more effective in returning the patient to sinus rhythm and significantly reduces the need for adenosine and other emergency anti-arrhythmic treatment compared to a standard VM. The modified VM should be considered for the routine emergency treatment of SVT in all settings.
 
Funding statement
The REVERT trial was funded by the National Institute for Health Research through its Research for Patient Benefit (RfPB) Programme (Grant Reference Number PB-PG-0211-24145). The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.
 
References
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