Proarrhythmic agents (Class 1A and 1C antiarrhythmics), vasodilators, depressants Conditions that mimic syncope Seizures Migraine Conversion disorder a Hyperventilation Pseudoseizures Intentional strangulation (e.g., “choking game”) Narcolepsy a Common causes of syncope life-threatening causes b Potentially It is crucial to obtain a full family history in patients suspected of having LQTS Some clinical features such as QT morphologic characteristics, the response of the QT interval to exercise, triggers of arrhythmia, and response to therapies vary according to the disease-associated gene In LQTS, recent and frequent syncopal episodes between the ages of 10 and 12 years, QTc prolongation >530 msec, and male gender are predictive of risk for aborted cardiac arrest and sudden cardiac death during adolescence Brugada Syndrome In this heritable disorder, there is an abnormality in the cardiac sodium channel that results in ST-segment elevation in anterior precordial leads (V1 and V2) with a susceptibility to polymorphic ventricular tachycardia The ECG pattern is diagnostic, but may be present only intermittently, and may change over time If the arrhythmia degenerates to ventricular fibrillation, it may lead to sudden death; if it terminates, the patient may have only syncope Structural Heart Disease Congenital heart conditions that interfere with cardiac output may result in syncope Such structural problems include hypertrophic obstructive cardiomyopathy (HOCM), aortic valve stenosis, and coronary anomalies that cause cardiac ischemia Functionally, pulmonary hypertension may cause similar results As with other cardiac causes of syncope, chest pain, dizziness, and dyspnea on exertion are concerning symptoms that should prompt further evaluation HOCM is a genetic disorder that affects the proteins of the cardiac sarcomere In this condition, the hypertrophied basal interventricular septum partially blocks