Adenosine vs. Diltiazem (AVNRTstdy)

March 4, 2026 updated by: Adem Az, Haseki Training and Research Hospital

Intravenous Adenosine Versus Diltiazem After Failed Modified Valsalva for Hemodynamically Stable ANVRT in the Emergency Department

In this Emergency Department (ED)-based study, the investigators evaluated a standardized modified Valsalva maneuver (MVM) as first-line therapy and compared intravenous (IV) adenosine with IV diltiazem among patients with persistent atrioventricular nodal re-entrant tachycardia (AVNRT)-consistent supraventricular tachycardia (SVT) after MVM, focusing on successful conversion to sinus rhythm. The investigators also assessed drug-related adverse events and clinically relevant treatment-course measures.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Supraventricular tachycardia (SVT) is a frequent cause of emergency department (ED) visits and typically presents as an abrupt-onset, regular tachycardia that can be highly symptomatic despite hemodynamic stability. Among regular narrow-complex SVTs, atrioventricular nodal re-entrant tachycardia (AVNRT) is one of the most common underlying mechanisms. Guidelines recommend modified Valsalva maneuver (MVM) as first-line therapy for hemodynamically stable regular narrow-complex SVT, followed by pharmacologic cardioversion when vagal maneuvers fail. However, while MVM has strengthened the non-pharmacologic first step, a clear emergency department (ED)-relevant comparative assessment of adenosine versus diltiazem specifically after failed MVM-with attention to conversion success, rescue therapy requirements, safety/tolerability, and clinically meaningful ED outcomes-remains warranted. This prospective, randomized, single-blind, single-center clinical trial evaluates the effectiveness of a standardized MVM and to compare the efficacy and adverse-event profiles of intravenous (IV) adenosine versus IV diltiazem among patients with persistent SVT after MVM. Consecutive adult patients with regular narrow-complex SVT consistent with AVNRT were randomized (1:1) to IV adenosine or IV diltiazem. Randomization was performed using a computer-generated sequence with allocation concealment (sequentially numbered, opaque, sealed envelopes). Treating clinicians were aware of group allocation in order to administer the assigned drug, whereas outcome assessors and the statistical team remained blinded throughout data collection and analysis. Adenosine was administered as a rapid IV push (6 mg over ~2 seconds) followed immediately by a 10-mL normal saline flush; the injected arm was briefly elevated to facilitate rapid central delivery. If tachycardia persisted and no rhythm conversion occurred within 1-2 minutes, additional doses of 12 mg and then 18 mg were administered using the same technique, per the study protocol. Diltiazem was administered intravenously as 0.25 mg/kg (maximum 20 mg) over approximately 2 minutes. If tachycardia persisted, a second dose of 0.35 mg/kg (maximum 25 mg) was administered after ~15 minutes. In patients who remained in SVT after protocolized dosing, subsequent management followed a predefined rescue algorithm based on hemodynamic status: hemodynamically stable patients received the alternative study drug (adenosine or diltiazem), whereas patients with signs of hemodynamic instability or persistent SVT despite sequential pharmacologic therapy underwent synchronized electrical cardioversion. In both groups, continuous clinical and electrocardiogram (ECG) monitoring was performed throughout the intervention period. For each eligible patient, baseline information was recorded at ED presentation, including age, sex, date/time of arrival, presenting symptoms, current medications, relevant comorbidities, and smoking and/or alcohol use history. Initial clinical and electrocardiographic data were documented, including heart rate, respiratory rate, systolic (SBP) and diastolic blood pressure (DBP), peripheral oxygen saturation (SpO2), and predefined ECG characteristics. In all patients who achieved sinus rhythm, vital signs (SBP/DBP, heart rate, and SpO2) were recorded immediately after conversion and at 10, 15, 30, and 60 minutes thereafter using standardized monitoring in the ED. The primary outcome was conversion to sinus rhythm with the allocated drug. Secondary outcomes included repeat dosing, time to conversion, adverse events, pause-related ECG events, crossover to the alternative drug, and disposition.

Study Type

Interventional

Enrollment (Actual)

140

Phase

  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Turkey (Türkiye)
    • Fatih
      • Istanbul, Fatih, Turkey (Türkiye), 34265
        • Haseki Training and Research Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Age ≥ 18 years
  • Presentation to the emergency department with hemodynamically stable, regular narrow-complex SVT consistent with AVNRT
  • a regular narrow-complex tachycardia with QRS duration <120 ms
  • no discernible P waves on the presenting rhythm strip or 12-lead ECG
  • a ventricular rate of 160-220 beats/min

Exclusion Criteria:

  • Contraindications to adenosine or diltiazem (known hypersensitivity to adenosine or diltiazem, prior heart transplantation, or concomitant dipyridamole/carbamazepine therapy)
  • Clinical evidence of impaired cerebral perfusion (e.g., altered mental status)
  • Pegnancy
  • Hemodynamic instability or respiratory failure requiring emergency intubation and advanced life support

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Adenosine group
The adenosine group received a rapid IV push of adenosine.
Drug: Adenosine intravenous
Adenosine was administered as a rapid IV push (6 mg over ~2 seconds) followed immediately by a 10-mL normal saline flush; the injected arm was briefly elevated to facilitate rapid central delivery. If tachycardia persisted and no rhythm conversion occurred within 1-2 minutes, additional doses of 12 mg and then 18 mg were administered using the same technique, per the study protocol.
Active Comparator: Diltiazem group
The diltiazem group received an IV bolus of diltiazem.
Drug: Diltiazem intravenous
Diltiazem was administered intravenously as 0.25 mg/kg (maximum 20 mg) over approximately 2 minutes. If tachycardia persisted, a second dose of 0.35 mg/kg (maximum 25 mg) was administered after ~15 minutes.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Conversion to sinus rhythm on continuous cardiac monitor/ECG without rescue therapy
Time Frame: Within 20 minutes after initiation of the assigned study drug
The outcome was cardiac rhythm (sinus rhythm vs persistent SVT) assessed using continuous ECG monitoring. Conversion was defined as sinus rhythm documented on the monitor and confirmed by a rhythm strip and/or 12-lead ECG, adjudicated by a blinded outcome assessor. "Successful conversion" required conversion with the randomized, initially assigned drug regimen (IV adenosine vs IV diltiazem) without crossover to the alternative drug, synchronized cardioversion, or other rescue therapy within the outcome time window.
Within 20 minutes after initiation of the assigned study drug

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Incidence of treatment-emergent adverse events and post-treatment ECG events assessed by continuous cardiac monitoring/ECG
Time Frame: Within 2 hours following the initial study drug administration

Treatment-emergent adverse events will be assessed using bedside clinical evaluation and patient-reported symptoms, and recorded prospectively on the study case report form. Prespecified adverse events include nausea, dyspnea, flushing, chest tightness, headache, and hypotension (blood pressure measured by standard noninvasive ED monitoring).

Post-treatment ECG events will be assessed using continuous cardiac monitoring with rhythm strips, with documentation and review by a blinded outcome assessor. A pause-related event is defined as a transient absence of QRS complexes (ventricular pause) lasting ≥3 seconds on the monitor strip; sinus arrest is defined as a pause meeting the same duration threshold with absent P-wave activity consistent with sinus node suppression. Additional post-treatment rhythm findings (e.g., bradycardia, atrial flutter, atrial fibrillation) will be recorded if present.
Within 2 hours following the initial study drug administration
Time to conversion to sinus rhythm (minutes) assessed by continuous ECG monitoring
Time Frame: Up to 60 minutes following the initial study drug administration (conversion time/status documented at 10, 15, 30, and 60 minutes)
Time to conversion was defined as the elapsed time (in minutes) from initiation of the assigned study drug administration (IV adenosine or IV diltiazem) to the first documented sinus rhythm on continuous cardiac monitoring, confirmed by a rhythm strip and/or 12-lead ECG. If sinus rhythm was not achieved within the observation window, the participant was recorded as not converted within 60 minutes (time-to-conversion not achieved within the window).
Up to 60 minutes following the initial study drug administration (conversion time/status documented at 10, 15, 30, and 60 minutes)
Need for rescue therapy (crossover to the alternative study drug) or synchronized electrical cardioversion
Time Frame: During the acute ED observation period, up to 60 minutes after initiation of the initially assigned study drug (or earlier if synchronized cardioversion is required).
This outcome will be assessed using continuous ECG monitoring and bedside clinical evaluation during the ED observation period. A "rescue therapy" event will be recorded if a participant requires crossover to the alternative study drug (adenosine ↔ diltiazem) due to persistent SVT despite the protocolized dosing of the initially assigned drug. A "synchronized cardioversion" event will be recorded if synchronized electrical cardioversion is performed due to hemodynamic instability and/or persistent SVT despite sequential pharmacologic therapy, per the predefined rescue algorithm.
During the acute ED observation period, up to 60 minutes after initiation of the initially assigned study drug (or earlier if synchronized cardioversion is required).

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Haseki Training and Research Hospital

Investigators

  • Principal Investigator: Adem Az, Haseki Training and Research Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

July 1, 2024

Primary Completion (Actual)

June 30, 2025

Study Completion (Actual)

August 30, 2025

Study Registration Dates

First Submitted

February 25, 2026

First Submitted That Met QC Criteria

March 4, 2026

First Posted (Actual)

March 6, 2026

Study Record Updates

Last Update Posted (Actual)

March 6, 2026

Last Update Submitted That Met QC Criteria

March 4, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 28-2024

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Stored in non-publicly available Available on request

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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