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Fever-induced Brugada pattern misdiagnosed as an acute myocardial infarction.

CASE REPORT

A 61-year-old man with a past medical history of hypertension, hypothyroidism, and morbid obesity presented to the emergency department due to profuse diarrhea and headaches. The patient stated that he was in his usual state of health until two days prior to presentation. The patient described 10 watery bowel movements per day. No blood or pus was noted in his stools. His headaches were located over the frontal area and nonradiating. He had associated symptoms of fever and indigestion. He denied chest pain, shortness of breath, palpitations, or edema. During his work up in the emergency department, he had an abnormal electrocardiogram (EKG), different from a prior EKG that prompted a STEMI Team activation (Figures 1,2). The patient had no known family history of cardiac problems including arrhythmias, syncope or sudden cardiac death. Vitals on presentation were: Temperature: 99.1[degrees] Fahrenheit, heart rate: 105 beats per min, 20 respirations per minute, pulse oximetry 99% on room air, weight of192 kilograms, height of 6 foot 3 inches and body mass index of 53. Pertinent positives on physical exam were mild tenderness to palpation of left upper and left lower quadrants of the abdomen and tachycardia. Pertinent negatives were normal jugular venous pressure, normal lung sounds and cardiac regular rhythm. Pertinent positive labs were blood leukocytosis of 21,000/[mm.sup.3] with 3% bands. BUN was elevated at 28 mg/dL and creatinine was elevated at 3.1 mg/dL. (the baseline creatinine was 1.1 mg/dL). His serum bicarbonate level was 16 mEq/L, his TSH was normal, but a mildly elevated FT4 at 1.53 ng/dL was found. The urinalysis was abnormal with positive leukocyte esterase on dipstick. Microscopic analysis showed too many white blood cells to count and many bacteria. Other pertinent lab results were normal troponin, CKMB, CKMB%, but elevated total CPK at 885. BNP was 78 pg/mL. The patient had computed tomography (CT) of the abdomen without contrast that revealed left-sided hydronephrosis and left hydroureter secondary to retroperitoneal fibrosis. The STEMI activation was cancelled and the patient was admitted for sepsis.

The patient had Enterococcus faecalis bacteremia from a genitourinary source. He was treated with appropriate antibiotics and had urologic intervention with left ureteral stenting. His hospital course was uneventful, and he was discharged with no cardiac sequelae. He had an outpatient biopsy of the retroperitoneal fibrosis indicating an idiopathic etiology. An EKG was repeated one month later afterresolutionofhis sepsis(Figure2).

DISCUSSION

Definition

The Brugada syndrome is an autosomal dominant genetic disorder with incomplete penetrance or polygenic inheritance affecting the sodium channels. Brugada syndrome is characterized by abnormal surface EKG findings in conjunction with an increased risk of ventricular tachyarrhythmias and sudden cardiac death. EKG findings typically consist of persistent ST segment elevation in leads V1 to V3 and the presence of a pseudo-right bundle branch block. These EKG changes are dynamic, often hidden, and may reveal themselves in the presence of triggers like fever, intoxication (alcohol, cocaine, or cannabis), vagal stimulation, electrolyte imbalance, anesthetics (propofol, bupivacaine), psychotropic agents (amitriptyline, lithium), and sodium channel blockers. (1) Patients with typical EKG features who are asymptomatic and have no other clinical criteria are said to have Brugada pattern such as the patient in this case.

Prevalence

The prevalence of Brugada syndrome appears to be low in the general population. A family history is present in about 2030% of patients. (10) According to recent studies in Europe, the incidence of sudden death in the general population (age 7-64 years) is 1.34 per 100,000 per year. (4) Studies in heterogeneous populations suggest that the majority of patients were of Asian decent. (5) However, one article looking at Brugada pattern on EKG stated none of the patients with fever-induced Brugada were of southeast Asian origin or had electrolyte imbalance, significant bradycardia, and prolonged PR interval when their type I pattern was recognized. In addition, none of the eight patients with fever-induced type I Brugada had a history suggestive of arrhythmic symptoms. (6) The prevalence of type I Brugada pattern is 20 times higher among patients presenting with fever than in afebrile patients (2% vs 0.1%).6

Pathophysiology

Genetic analysis in patients with Brugada syndrome has shown an association with sodium channel SCN5A mutations in about 20% of the cases. (2) This patient had Brugada Type 1 EKG pattern induced by fever. The predominance of outward ionic current (Ito) at the end of phase 1 of the action potential either because of an increase of its magnitude or because of a decrease in inward currents (INa, ICaL) causes loss of the action potential dome with marked shortening of the action potential. The greater density of the Ito current in the epicardium causes a transmural dispersion of repolarization that manifest as a J wave or ST-segment elevation. (7) Accelerated inactivation of the sodium channel can be temperature-sensitive. (8) Fever might also impair conductance of the sodium channel. (9)

Diagnosis

Expert Consensus statement for type 1 and type 2 Brugada are defined (3):

1. Brugada syndrome is diagnosed in patients with ST-segment elevation with type I morphology [greater than or equal to]2 mm in [greater than or equal to] 1 lead among the right precordial leads V1,V2 positioned in the 2nd, 3rd, or 4th intercostal space occurring either spontaneously or after provocative drug test with intravenous administration of Class I antiarrhythmic drugs

2. Brugada syndrome is diagnosed in patients with Type 2 or Type 3 ST-segment elevation in [greater than or equal to]1 lead among the right precordial leads V1,V2 positioned in the 2nd, 3rd, or 4th intercostal space when a provocative drug test with intravenous administration of Class I antiarrhythmic drugs induces a Type 1 EKG morphology.

Prognosis and Risk Stratification

The relation between the Brugada EKG sign in asymptomatic patients (no history of syncope, ventricular arrhythmias or SCD (sudden cardiac death)) and the future risk of developing arrhythmogenic events has been investigated. One study revealed that the cardiac event rate per year in asymptomatic patients was 0.5%, compared to 1.9% in patients with a history of syncope and 7.7% in patients with aborted SCD. (13) Multiple predictors of future arrhythmic events in patients with the Brugada pattern were studied, with male gender, mutation of the SCN5A gene and a positive family history of SCD found to be non -predictive. (13,14,15) The prognostic value of the clinical, EKG and Electrophysiology Studies (EPS) variables were analyzed in a population of spontaneous type 1 Brugada ECG patterns and no previous cardiac arrest. The cohort with negative EPS (non-inducibility of VT/VF) had a 1.8% risk of developing arrhythmic events (SCD or documented VF), compared to 14% in those with a positive EPS. (15) Further studies revealed a 0.9% rate of significant cardiac events in patients with non-inducible arrhythmias. (14,15) A positive EPS is not predictive for arrhythmic events, and data reported that the spontaneous ECG pattern and the history of syncope are the best available predictors of such events. (13,16)

Therapies

An Implantable Cardioverter (ICD) Device is the only proven effective therapeutic strategy for the prevention of SCD in Brugada syndrome. It is important to note that ICD's do have disadvantages, especially young active individuals, who will require multiple device replacements during their life-time. Asymptomatic Brugada syndrome patients do not qualify for an ICD as their risk for life threatening events is very low. (17)

Isoproterenol (which increases the L-type calcium current), has proved to be useful for treatment of electrical storm in Brugada syndrome but controlled data on its therapeutic role are not available. (18)

Quinidine, a Class la antiarrhythmic drug with Ito and IKr blocker effects, has been shown to prevent induction of VF and suppress spontaneous ventricular arrhythmias in a clinical setting. Quinidine is currently being used in patients with ICD and multiple shocks; cases in which ICD implantation is contraindicated; or for the treatment of supraventricular arrhythmias. (17) It has been suggested that quinidine could also be useful in children with Brugada syndrome, as a bridge to ICD or as an alternative to it. (17) Randomized studies on the use of quinidine, however, have not been performed.

Radiofrequency Ablation (RFA) of ventricular ectopy has been postulated as a therapeutic approach in Brugada syndrome patients. A recent study by Josep Brugada et al. showed prevention and treatment of Brugada syndrome by RFA. This study had pathophysiologic and therapeutic implications. Substrate epicardial mapping and ablation guided by provocative testing was considered a reproducible, safe and effective strategy to definitively treat patients with type 1 Brugada syndrome EKG pattern and risk of sudden death. (19)

CONCLUSION

The Brugada pattern includes a pattern resembling RBBB with elevation of the ST segment in the precordial leads (V1V2). Physicians should be aware of other causes inducing ST segment elevation. A good clinical history and a low clinical suspicion for ischemia may avoid the inappropriate utilization of emergency catheterization and of hospital resources. Fever has been described to induce a Brugada-type EKG pattern in asymptomatic patients with a negative family history. (12) The expert consensus statement from the HRS/EHRA/APHRS gives a class I indication to provide immediate treatment of fever with antipyretic drugs. (3) Furthermore, avoidance of excessive alcohol intake and drugs that may induce or aggravate ST-segment elevation in right precordial leads are class I indications. Risk stratification of asymptomatic patients with a Brugada-type EKG induced by fever and a negative family history remains a matter of debate. According to current guidelines, careful follow-up would be an appropriate option. (11) The diagnostic value of a drug challenge test as well as electrophysiological studies in this population is uncertain. Our patient was asymptomatic with a negative family history and given close follow up.

REFERENCES

(1.) Bayes de Luna A, Brugada J, Baranchuk A, et al. Current electrocardiographic criteria for diagnosis of Brugada pattern: a consensus report. J Electrocardiol. 2012;45:433-442.

(2.) Probst V, Wilde AA, Barc J, et al. SCN5A mutations and the role of genetic background in the pathophysiology of Brugada syndrome. Circ Cardiovasc Genet. 2009;2:552-557.

(3.) S.G. Priori, A.A. Wilde, M. Horie, Y. Cho, E.R. Behr, C. Berul, et al. HRS/EHRA/ APHRS Expert Consensus Statement on the Diagnosis and Management of Patients with Inherited Primary Arrhythmia Syndromes: Document endorsed by HRS, EHRA, and APHRS in May 2013 and by ACCF, AHA, PACES, and AEPC in June 2013 Heart Rhythm, 10 (2013), pp. 1932-1963.

(4.) Behr ER, Dalageorgou C, Christiansen M, Syrris P, Hughes S, Tome, Esteban MT, Rowland E, Jeffery S, McKenna WJ. Sudden arrhythmic death syndrome: familial evaluation identifies inheritable heart disease in the majority of families. Eur Heart J. 2008;29:1670-1680.

(5.) Alings M. Wilder A. "Brugada" Syndrome: clinical data and suggested pathophysiological mechanism. Cirulation 1999;78:581.

(6.) Arnon Adler, et al. Fever-induced Brugada pattern: How common is it and what does it mean? Heart Rhythm. 2013;10(9):2-5.

(7.) Benito B, Brugada J, Brugada R, Brugada P. Brugada syndrome. Rev Esp Cardiol. 2009;62:1297-1315.

(8.) Dumaine R, Towbin JA, Brugada P, Vatta M, Nesterenko DV, Nesterenko VV, Brugada J, Brugada R, Antzelevitch C. Ionic mechanisms responsible for the electrocardiographic phenotype of the Brugada syndrome are temperature dependent. Circ Res. 1999;85:803-809.

(9.) Deschenes I, Laurita KR. How can a single mutation cause such arrhythmic havoc? Heart Rhythm. 2007;4:198-199.

(10.) Vohra Jitendra, et. al. Update on the Diagnosis and Management of Brugada Syndrome. Heart, Lung and Circulation. 2015;24:1141-1148.

(11.) Antzelevitch C, Brugada P, Borggrefe M, Brugada J, Brugada R, Corrado D, Gussak I, LeMarec H, Nademanee K, Perez Riera AR, et al. Brugada syndrome: report of the second consensus conference: endorsed by the Heart Rhythm Society and the European Heart Rhythm Association. Circulation. 2005;111:659-670.

(12.) Nguyen T, Smythe J, Baranchuk A. Rhabdomyoma of the interventricular septum presenting as a Brugada phenocopy. Cardiol Young. 2011;21:591594.

(13.) Probst V, Veltmann C, Eckardt L, et al. Long-term prognosis of patients diagnosed with Brugada syndrome. Results from the FINGER Brugada Syndrome Registry. Circulation 2010;121(5):635-43.

(14.) Brugada J, Brugada R, Antzelevitch C, et al. Long-term follow-up of individuals with the electrocardiographic pattern of right bundle-branch block and STsegment elevation in precordial leads V1 to V3. Circulation 2002;105(1):73-8.

(15.) Brugada J, Brugada R, Brugada P. Determinants of sudden cardiac death in individuals with the electrocardiographic pattern of Brugada syndrome and no previous cardiac arrest. Circulation 2003;108(25):3092-6.

(16.) Priori SG, Gasparini M, Napolitano C, et al. Risk stratification in Brugada syndrome: results of the PRELUDE (PRogrammed ELectrical stimUlation preDictive valuE) registry. J Am Coll Cardiol 2012;59(1):37-45.

(17.) Mizusawa Y, Wilde AA. Brugada syndrome. Circ Arrhythm Electrophysiol. 2012;5:606-616.

(18.) Priori Silvia G., et.al. HRS/EHRA/APHRS Expert Consensus Statement on the Diagnosis and Management of Patients with Inherited Primary Arrhythmia Syndromes. Heart Rhythm 2013;10(12): 1937-1940.

(19.) Brugada Josep, et. al. Brugada Syndrome Phenotype Elimination by Epicardial Substrate Ablation. Circulation 2015;8(6):1373-1381.

David Tadin, MD; Roberto Quintal, MD

Dr. Tadin is a cardiology fellow at LSUHSC-New Orleans; Dr. Quintal is a retired chief of cardiology at LSU and at Touro Infirmary, both in New Orleans.

Caption: FIGURE 1: Brugada type I EKG pattern in leads [V.sub.1], [V.sub.2] on admission with sepsis.

Caption: FIGURE 2: Baseline EKG from two years ago.

Caption: FIGURE 3: EKG showing resolution of Brugada type I pattern after resolution of sepsis.
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Author:Tadin, David; Quintal, Roberto
Publication:The Journal of the Louisiana State Medical Society
Article Type:Case study
Date:Jan 1, 2017
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