VENTRICULAR FIBRILLATION
Brugada-like electrocardiographic pattern and ventricular fibrillation in a patient with primary hyperparathyroidism
1 Department of Cardiology, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, 199, Tunhwa N. Road, Taipei, Taiwan, Republic of, China; 2 Department of Cardiology, RIPAS Hospital, Bander Seri Begawan, Brunei Darussalam
Manuscript submitted 20 July 2006. Accepted after revision 17 December 2006.
* Corresponding author. Tel: +886 33281200 ext.8162; fax: +886-33271192. E-mail address: chitai{at}adm.cgmh.org.tw
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Abstract |
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There are several causes for ST segment abnormalities in leads V1 to V3. Hypercalcaemia and Brugada syndrome are among them. Both are known to produce ventricular arrhythmia, albeit only rare cases have been reported with documented evidence of ventricular arrhythmias in association with a hypercalcaemic crisis but none when hypercalcaemic coexists with Brugada syndrome. We describe a patient with primary hyperparathyroidism who presented with ventricular fibrillation, and the ECG showed changes similar to Brugada syndrome. The provocation test with flecainide was conducted twice. This was positive, both before and after parathyroidectomy when serum calcium and parathormone levels had normalized. The patient was treated for hypercalcaemia and underwent parathyroidectomy. This is the first report of oral flecainide test unmasking the diagnostic coved Brugada ECG pattern in a patient with primary hyperparathyroidism and raising attention to hypercalcaemia as a potential trigger for life-threatening arrhythmia in Brugada syndrome.
Key Words: Ventricular fibrillation, Hyperparathyroidism, Hypercalcaemia, Brugada syndrome
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Case report |
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A 57-year-old man, hypertensive for 4 years, defaulted medication for months, presented with a first episode of syncope, associated with sweating, pallor, and an upward gaze while he was talking to his friends. This episode lasted 1–2 min and subsided after receiving a gentle neck massage by his friends. There was no family history of coronary artery disease or sudden cardiac death. While on his way to the emergency room, he had another similar episode of syncope. Upon arrival, he had regained consciousness and vital signs were stable. A 12-lead ECG showed coved ST elevation in leads V1 and V2 (Figure 1). Another episode of syncope occurred soon after arrival. This was associated with ventricular fibrillation (VF), as witnessed on the cardiac monitor in the emergency room. The arrhythmia was successfully converted to sinus rhythm with a single shock of 150 J.
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His initial blood pressure was 136/85 mmHg, heart rate 59 bpm, regular, respiratory rate 15 per minute and he was afebrile. Physical examination was unremarkable and cardiac enzymes were normal. Corrected serum calcium was 12.5 mg/dL, Magnesium, 1.9 meq/L, potassium, 3.1 meq/L (normal range in this laboratory 3.0–4.8 meq/L), and i-PTH, 934 pg/ml (elevated).
He was admitted to the coronary care unit. A 12-lead ECG taken 6 h after admission showed a saddle-back type II Brugada morphology in leads V1 and V2. These abnormalities were not present when the ECG was repeated on day 2. Computerized tomography of brain, chest X-ray, echocardiogram, and Tc 99 m sestamibi scan of the heart did not reveal any abnormalities. Primary hyperparathyroidism was suspected, and a parathyroid scan revealed hyperplasia of the right upper thyroid bed. After hydration with normal saline and bisphosphonate infusion, the calcium level fell to 8.6 mg/dL. During the subsequent 7 days, he did not sustain further syncope or VF and he was transferred from CCU to the general ward.
Parathyroidectomy was planned, and preoperative evaluation included a provocative test with flecainide, cardiac catheterization, and an electrophysiological study. Flecainide was administered at a dose of 400 mg orally, and 50 min later the ECG changed from a saddle-back type II to a coved-type ST–T change in leads V1 and V2 (Figure 2). Coronary angiogram showed normal coronaries and good left-ventricle function. Upon electrophysiological study, we could not induce ventricular tachycardia or VF after vigorous programmed stimulation (S1S1 down to 200 ms, S1S4 at pacing cycle lengths of 400 and 500 ms from both the RV apex and RV outflow tract).
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The patient underwent uncomplicated parathyroidectomy and histopathology confirmed parathyroid adenoma. Cardiac magnetic resonance imaging was performed and did not show any signs of right ventricular dysplasia.
Flecainide test was repeated 1 week after parathyroidectomy when both the serum calcium and i-PTH levels were within the normal range. The ECG changed from normal to one with coved type ST–T change in leads V1 and V2 (70 min after administration of flecainide) (Figure 3). Thus, the diagnosis of primary hyperparathyroidism and Brugada syndrome with VF was suspected. An implantable cardiac defibrillator (ICD) implant was advised. However, the patient hesitated about it. He was discharged without ICD implant and has visited our outpatient department regularly. We also studied PCR-DNA sequencing for this patient, in order to study mutation of cardiac sodium channel gene (SCN5A). We could not demonstrate any mutation in the SCN5A coding sequence.
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Following discharge from the hospital, the patient is doing well at 1 year of follow-up. He is asymptomatic and a repeat Holter recording did not show any ventricular arrhythmias.
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Discussion |
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As Gussak et al. pointed out that there are at least 17 causes of alteration in the ST segment in leads V1 to V3.1
Hypercalcaemia and Brugada syndrome are among them. The ECG changes of ST segment coving could thus be related to Brugada syndrome or to hypercalcaemia in this patient. Brugada and colleagues demonstrated that Class I drugs could identify patients in whom the Brugada syndrome was concealed, by the flecainide test, which unmasks the ECG pattern characteristic of the syndrome, with a high specificity and sensitivity.2
In this patient, we conducted the provocative test with flecainide twice at a dose of 400 mg orally.3 One was performed after normalizing serum calcium level before parathyroidectomy and the other after parathyroidectomy when both serum calcium as well as i-PTH were normal. Coved type ST–T changes developed in both of them. Therefore, the diagnosis of Brugada syndrome was suspected, regardless of whether the ST elevation was related to hypercalcaemia or not.
Polymerase chain reaction-DNA sequencing for this patient did not demonstrate any mutation in the coding sequence of cardiac sodium channel gene (SCN5A). To date, SCN5A has been identified and it accounts for 30% or even less of clinical cases.4 Therefore, a negative finding for the mutation of the cardiac sodium channel gene does not exclude a diagnosis of Brugada syndrome.
In a patient such as ours, it is important from the risk stratification point of view to know whether the VF was due to hypercalcaemia, Brugada syndrome, or both. If the VF was related to Brugada syndrome, the patient falls into a high-risk group, and ICD implantation is indicated (Class I).5 On the other hand, if it is related solely to hypercalcaemia, parathyroidectomy is the definitive treatment. Furthermore, programmed stimulation could not induce ventricular arrhythmia, potentially avoiding the need for an ICD implant.6
Case reports of documented VF in association with hypercalcaemic crisis are rare.7–9 Before attributing the VF to hypercalcaemia in such cases, solely because of the presence of the electrolyte disorder, other possible causes should also be sought. Brugada syndrome, though not very common, is an important cause of ventricular arrhythmia to be identified in such cases. This case report shows for the first time that hyperparathyroidism can coexist with other causes of ventricular arrhythmia, in this case Brugada syndrome and thus create management dilemma. In the present case, it was difficult to pinpoint the exact cause of the VF, yet in the interest of patient safety we advised an ICD implant.
The course of clinical follow-up has been uneventful. It is reasonable to say that hypercalcaemia is a potential trigger of ventricular arrhythmia in Brugada syndrome in this case. Furthermore, it may be warranted to evaluate calcium plasma level when assessing these patients.
In summary, this is the first report, in which primary hyperparathyroidism has been documented in association with positive provocation test with Flecainide for Brugada syndrome, both of which are capable of producing lethal ventricular arrhythmia.
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References |
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