The flecainide test is a pharmacological test for provocation of the Brugada electrocardiographic pattern (B-ECG), a fundamental tool in the diagnosis of this syndrome related to ventricular arrhythmias and sudden death.
Sodium channel blocking antiarrhythmic drugs, mainly ajmaline and flecainide (in our setting), are the most used due to their proven effectiveness and safety in unmasking BECG.
Despite the superiority of ajmaline, the fact that it is not available in many countries has made flecainide the drug of choice in most electrophysiology laboratories. The differences between both drugs have been related to the greater inhibition exerted by flecainide on the transient potassium outflow current (Ito), decreasing the ionic imbalance between the positive input and output currents at the end of phase 1 of the action potential. which allows the B-ECG to be unmasked.
The test is considered positive if, during drug infusion, a non- diagnostic B-ECG (type 2 or 3) becomes a diagnostic B-ECG (type 1 or coved type), characterized by ST-segment elevation ≥ 2 mm followed by T wave inversion in more than one right precordial lead (V1-V3). These tests are usually performed on an outpatient basis, and once the electrocardiogram has normalized, the patient is discharged after a brief period of monitoring.
Although it is generally considered a safe test, in certain patients it can trigger ventricular arrhythmias (polymorphic ventricular extrasystole, atrioventricular block, ventricular tachycardia and ventricular fibrillation), especially in carriers of the SCN5A gene mutation responsible for DS. of Brugada, even if they are asymptomatic. That is why this test must be performed in an environment appropriate for monitoring and with cardiopulmonary resuscitation capacity along with adequate medical supervision by electrophysiology specialists.
TEST DEVELOPMENT
The pharmacological provocation test with flecainide should be performed in a room with continuous monitoring and cardiopulmonary resuscitation equipment, since a small percentage (0.5%) of patients can develop ventricular fibrillation, by cardiologists specialized in arrhythmias and electrophysiology together with nursing staff. trained in this type of procedures following the following steps:
1. Provide exhaustive information on the procedure and verification of the signing of the informed consent.
2. The test must be performed in a room equipped with drugs and adequate cardiopulmonary resuscitation material, which must be constantly reviewed.
3. Peripheral venous line cannulation, baseline ECG and baseline blood pressure (BP) measurement.
4. Dilute 1 ampoule of 150 mg in 100 cc of glucose serum.
5. Administer 2 mg/kg in 10 minutes (maximum dose 150 mg).
6. ECG monitoring with a continuous polygraphy system for early detection of changes in the ECG as well as arrhythmias that may occur during the test by placing electrodes in conventional precordials V1 and V2, as well as high precordials.
7. Taking BP and ECG every 2 minutes for 30 minutes.
8. Stop the test if:
to. ECG is observed with Brugada pattern morphology
b. Extrasystoles or ventricular arrhythmias are observed
c. QRS widening >130%
9. Outpatient clinical observation for 4-6 hours.
10. Performing an ECG before discharge.
11. Inform the patient with the results of the test and recommendations for further evaluation by their specialist.
BIBLIOGRAPHY
1. K. Hong, J. Brugada, A. Oliva, A. Berruezo-Sánchez, D. Potenza, GD Pollevick, et al. Value of electrocardiographic parameters and ajmaline test in the diagnosis of Brugada syndrome caused by SCN5A mutations. Circulation, 110 (2004), pp. 3023-3027
2. G. Meregalli, J. Ruijter, N. Hofman, C. Bezzina, A. Wilde, H. Tan. Diagnostic value of flecainide testing in unmasking SCN5A-related Brugada syndrome. J Cardiovasc Electrophysiol., 17 (2006), pp. 857-864
3. C. Wolpert, C. Echternach, C. Veltmann, C. Antzelevitch, GP Thomas, S. Spehl, et al. Intravenous drug challenge using flecainide and ajmaline in patients with Brugada syndrome. Heart Rhythm., 2 (2005), pp. 254-260
4. M. Gasparini, SG Priori, M. Mantica, C. Napolitano, P. Galimberti, C. Cerlotti, et al. Flecainide test in Brugada syndrome: a reproducible but risky tool. Pacing Clin Electrophysiol., 26 (2003), pp. 338-341.
5. M. Abello, JL Merino, R. Peinado, M. Gnoatto. Negative flecainide test in Brugada syndrome patients with previous positive response. Europace., 8 (2006), pp. 899-900
6. Obeyesekere MN, Klein GJ, Modi S, Leong-Sit P, Gula LJ, Yee R, Skanes AC, Krahn AD. How to perform and interpret provocative testing for the diagnosis of Brugada syndrome, long-QT syndrome, and catecholaminergic polymorphic ventricular tachycardia. Circ Arrhythm Electrophysiol. 2011 Dec;4(6):958-64.
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