Etiologies and Predictors of ST-Segment Elevation Myocardial Infarction

BACKGROUND AND OBJECTIVES: Rapid diagnosis of ST-segment elevation myocardial infarction (STEMI) is essential for the appropriate management of patients. We investigated the prevalence, etiologies and predictors of false-positive diagnosis of STEMI and subsequent inappropriate catheterization laboratory activation in patients with presumptive diagnosis of STEMI. SUBJECTS AND METHODS: Four hundred fifty-five consecutive patients (62+/-13 years, 345 males) with presumptive diagnosis of STEMI between August 2008 and November 2010 were included. RESULTS: A false-positive diagnosis of STEMI was made in 34 patients (7.5%) with no indication of coronary artery lesion. Common causes for the false-positive diagnosis were coronary spasm in 10 patients, left ventricular hypertrophy in 5 patients, myocarditis in 4 patients, early repolarization in 3 patients, and previous myocardial infarction and stress-induced cardiomyopathy in 2 patients each. In multivariate logistic regression analysis, symptom-to-door time >12 hours {odds ratio (OR) 4.995, 95% confidence interval (CI) 1.384-18.030, p=0.014}, presenting symptom other than chest pain (OR 7.709, 95% CI 1.255-39.922, p=0.027), absence of Q wave (OR 9.082, CI 2.631-31.351, p<0.001) and absence of reciprocal changes on electrocardiography (ECG) (OR 17.987, CI 5.295-61.106, p<0.001) were independent predictors of false-positive diagnosis of STEMI. CONCLUSION: In patients whom STEMI was planned for primary coronary intervention, the false-positive diagnosis of STEMI was not rare. Correct interpretation of ECGs and consideration of ST-segment elevation in conditions other than STEMI may reduce inappropriate catheterization laboratory activation.

Erratum: Etiologies and Predictors of False-Positive Diagnosis of ST-Segment Elevation Myocardial Infarction

On page 370, Article Title has been incorrectly marked Etiologies and Predictors of ST-Segment Elevation Myocardial Infarction. The correct title is Etiologies and Predictors of False-Positive Diagnosis of ST-Segment Elevation Myocardial Infarction.

Recurrent Syncope Episodes and Exercise Intolerance in Hypertrophic Cardiomyopathy Combined with Atrioventricular Conduction Disturbance

A 30-year-old female patient with known hypertrophic cardiomyopathy (HCMP) was admitted for recurrent syncope episodes. Electrocardiogram (ECG) showed 2 : 1 atrioventricular (AV) block. Stress echocardiography with bicycle showed high grade AV block at high stage of the exercise associated with exercise intolerance and dyspnea. Twenty-four hour ECG monitoring also revealed high grade AV block and 1 episode of non-sustained ventricular tachycardia. Implantable cardioverter/defibrillator-pacemaker (ICD-P) was inserted. After implantation of ICD-P, conduction disturbance and exercise intolerance were improved. AV block is a rare complication HCMP. There are just a few case reports that present symptoms caused by conduction disturbance in HCMP. This case describes repeated syncope episodes and exercise intolerance caused by conduction disturbance during exercise in HCMP patient. For evaluating the cause of syncope in HCMP, stress echocardiography can be helpful to understand the probable mechanism of syncope.

Aseptic Endocarditis in Behcet's Disease Presenting as Tricuspid Valve Stenosis

Aseptic endocarditis is an uncommon complication of Behcet's disease (BD). We describe a rare case of a 39-year-old female who had BD with aseptic endocarditis of the tricuspid valve (TV) presenting as tricuspid stenosis. She was diagnosed with BD four years ago. The mucocutaneous lesions were well-controlled with colchicine and short courses of corticosteroids. She remained free of signs and symptoms of BD for one year without any medication. Three months before admission, she gradually developed dyspnea on exertion and peripheral edema. Echocardiography revealed dilated right atrium and markedly thickened TV with severe stenosis. TV replacement was performed. Pathologic examination of the valve showed fibrinoid necrotic material and inflammatory cell infiltration. Blood cultures and cultures of the excised valve were negative for microorganisms.

Epinephrine-Induced Polymorphic Ventricular Tachycardia in a Patient With Congenital Long QT Syndrome

A 24-year-old woman presented to the department of plastic surgery for surgical excision of a nevus on her nose. Although her history failed to reveal any cardiac disease, her pre-operative electrocardiogram (ECG) showed an extremely prolonged QT interval of up to 528 msec. Repeated history-taking after admission revealed three syncopal episodes associated with both physical and emotional stress, and because the two-dimensional echocardiography and exercise ECG test were normal except for the prolonged QT interval, an epinephrine test was done to assess QT interval changes after an epinephrine infusion. Immediately after a bolus injection of epinephrine (0.1 microgram/kg), marked prolongation of the QT interval developed, followed by polymorphic ventricular tachycardia which was immediately terminated with direct current shock, resulting in the diagnosis of a long QT syndrome (LQTS), probably type 1. Gene studies were recommended, but declined by the patient and her family. She was instructed to avoid competitive sports, and a beta-blocker was prescribed after which she remained symptom-free.

A Case of Coronary Artery Dissection After Aortic Replacement in Acute Type A Aortic Dissection

A 59-year-old woman was transferred to our institution with a diagnosis of acute type A aortic dissection. During aortic replacement surgery, the dissection had not extended to the orifice of the left coronary artery. However, ST segment elevation was observed on an electrocardiogram monitor immediately postoperatively. An emergent coronary angiogram showed almost complete collapse of the lumen of the left coronary artery due to pulsatile compression of the false lumen, which was caused by extension of the aortic dissection. Percutaneous coronary intervention (PCI) was performed with placement of stents in the left anterior descending artery (LAD) and left circumflex artery. Coronary angiography and intravascular ultrasound performed 45-days after PCI showed significant instent restenosis (ISR) at the proximal portion of the LAD and residual coronary artery dissection of the diagonal branch. Repeat balloon angioplasty was performed at the site of the ISR. A follow-up coronary angiogram 8-months after the PCI showed no evidence of ISR.