Clinical valuation of ST changes in a group of patients with ventricular arrhythmias: The inSighT Study.

BACKGROUND: The inSighT study was designed to determine the prevalence of ischemic changes as recorded by implantable cardioverter-defibrillator (ICD) ST deviations in intracardiac electrocardiograms (EGM) over the 24 h preceding malignant ventricular arrhythmias (VT/VF). METHODS: The study enrolled patients with known coronary artery disease (CAD) or high risk of future development of CAD implanted with an ICD equipped with an ST monitoring feature (Ellipse™/Fortify Assura™, St. Jude Medical). Device session records were collected at each in-clinic follow-up. EGM ST levels of the beats over the 15 minutes prior to VT/VF events were compared using a t test with those from a baseline period of 23-24 h prior to the VT/VF event. All events with p < .05 were visually inspected to confirm they were evaluable; additional criteria for exclusion from further analysis included inappropriate therapy, aberrant conduction, and occurrence of VT/VF within 24h prior to the current event. RESULTS: The study enrolled 481 ICD patients (64 ± 11 years, 83% male) in 14 countries and followed them for 15±5 months. A total of 165 confirmed VT/VF episodes were observed, of which 71 events (in 56 patients, 34% of all patients with VT/VF) were preceded by significant (p < .05) ST-segment changes unrelated to known non-ischemic causes. None of the analyzed demographic and clinical factors proved to be associated with greater odds of presenting with ST-segment changes prior to VT/VF episode. CONCLUSION: In this exploratory study, characteristic ST-segment changes, likely representative of ischemic events, were observed in 34% of all patients with VT/VF episodes.

Conventional and alternative preimplantation ECG screening for subcutaneous ICD in high risk hypertrophic cardiomyopathy patients.

INTRODUCTION: Patients with hypertrophic cardiomyopathy (HCM) relatively often fail preimplantation ECG screening for subcutaneous implantable cardioverter-defibrillator (S-ICD). We aimed to evaluate impact of conventional and alternative ECG electrodes placement on eligibility for S-ICD implantation in HCM patients at high risk of sudden cardiac death (SCD). We hypothesized that modified electrodes placement will influence QRS-T morphology and thus it will increase S-ICD eligibility in the screening process. MATERIAL AND METHODS: This study enrolled 17 HCM patients at high risk of SCD (5-year SCD risk above 5%) referred for an ICD implantation. ECG screening for S-ICD eligibility in horizontal and vertical position was performed in each patient, in two different screening electrodes configuration: conventional (recommended by manufacturer) and alternative (precordial electrodes shifted rightwards and lateral electrodes dorsally). We evaluated QRS and T waves amplitude as well as T wave index. Primary, secondary and alternate sensing vectors were assessed. RESULTS: Preimplantation ECG screening with alternative electrodes placement resulted in more sensing vectors that were screened successfully (77 vs. 88, p = 0.05). Modified screening combined with a standard one allowed more patients to qualify for S-ICD implantation (17/17 vs. 12/17, p = 0.04). Electrocardiographically, the alternative positioning of ECG electrodes resulted in significant decrease in absolute values of QRS complex and T waves amplitudes in almost all sensing vectors, which was responsible for successful screening. CONCLUSIONS: The use of alternative placement of screening electrodes may be a valuable method to increase eligibility for S-ICD implantation in HCM patients at high risk of SCD.

Severe atrial fibrosis as a cause of significant intraatrial conduction delay in a patient with scleromyositis.

Scleromyositis is an autoimmune disease and an overlap syndrome of scleroderma and poly/dermatomyositis. It is characterized by frequent cardiovascular involvement including heart failure, arrhythmias and conduction disturbances. We present a case of a 73-year old female patient who required an upgrade from a DDD pacemaker to cardiac resynchronization therapy due left ventricular dysfunction and permanent ventricular pacing. Electroanatomical mapping (CARTO 3D) revealed extensive right atrial fibrosis which resulted in significant delay in intraatrial conduction. Interval from atrial paced stimulus to A signal in His bundle was 364 ms, while AH and HV intervals were within normal range.

Repolarization abnormalities in carbon monoxide poisoning - a case report.

Each year a notable number of fatal intoxications with carbon monoxide (CO) is reported worldwide. Carbon monoxide binds with hemoglobin, decreases oxygen supply and leads to hypoxia and lactic acidosis. Myocardium, being particularly vulnerable to hypoxia, is one of the most damaged organs in course of CO intoxication. A CASE REPORT: We present a case report of severe CO poisoning in a 66-year old man, that led to significant repolarization abnormalities. Diffuse ST segment depression associated with significant QT interval prolongation up to QTcB 595ms was observed in the electrocardiogram at admission. Other potential causes of QT prolongation as hypothermia, dyselectrolitemia or QT prolonging drugs use were excluded. No regional neither global contractility dysfunction was observed on echocardiography. ECG recorded 6 hours after admission showed normalization of ST segment but only slight shortening of QTc to 550 ms.

Self-terminating ventricular fibrillation recorded by an implantable loop recorder as a cause of syncope - A case report.

Ventricular fibrillation (VF) is the most common arrhythmia leading to sudden cardiac death, but in rare cases VF can manifest as a syncope, provided that it will self-terminate. We present a case of a 45-year old female with a history of unexplained syncopal episodes despite exhaustive diagnostics. Implantable loop recorder documented an episode of idiopathic, self-terminating VF as a cause of syncope.