Arrhythmia monitoring and outcome after myocardial infarction (BIO|GUARD-MI): a randomized trial.

Objectives: Cardiac arrhythmias predict poor outcome after myocardial infarction (MI). We studied if arrhythmia monitoring with an insertable cardiac monitor (ICM) can improve treatment and outcome.

Design: BIO|GUARD-MI was a randomized, international open-label study with blinded outcome assessment.

Risk of arrhythmias after myocardial infarction in patients with left ventricular systolic dysfunction according to mode of revascularization: a Cardiac Arrhythmias and RIsk Stratification after Myocardial infArction (CARISMA) substudy.

Aims: The Cardiac Arrhythmias and RIsk Stratification after Myocardial infArction (CARISMA) study was an observational trial including 312 patients with acute myocardial infarction (MI) and left ventricular ejection fraction (LVEF) <40%. Primary percutaneous intervention (pPCI) was introduced 2 years after start of the enrolment, dividing the population into two groups: pre- and post-pPCI. This substudy sought to describe the influence of the mode of revascularization on long-term risk of new-onset atrial fibrillation (AF), bradyarrhythmia, and ventricular tachycardia and the subsequent risk of relevant major cardiovascular events (MACE).

The clinical effect of arrhythmia monitoring after myocardial infarction (BIO-GUARD|MI):study protocol for a randomized controlled trial.

Background: The increasing use of implantable cardiac monitors (ICMs) allows early documentation of asymptomatic cardiac arrhythmias that would previously have gone unnoticed. The addition of remote monitoring to cardiac devices means that physicians receive an early warning in cases of new-onset arrhythmias. While remote monitoring has been suggested to increase survival in heart failure patients with implantable defibrillators, trials using ICMs for continuous electrocardiographic monitoring of cardiac arrhythmias in the postmyocardial infarction setting have shown that patients who experienced cardiac arrhythmias such as atrial fibrillation, bradycardia, and ventricular tachyarrhythmia have an increased risk of major adverse cardiac events.

New strict left bundle branch block criteria reflect left ventricular activation differences.

Aims: Pacing lead electrical delays and strict left bundle branch block (LBBB) criteria were assessed against cardiac resynchronization therapy (CRT) outcome.

Methods: Forty-nine patients with LBBB and QRS duration >130 milliseconds underwent CRT-implantation. Sensed right ventricular to left ventricular electrical delay (RV-LV-IED) was measured.

Improving clinical practice guidelines for practicing cardiologists.

Cardiac-related clinical practice guidelines have become an integral part of the practice of cardiology. Unfortunately, these guidelines are often long, complex, and difficult for practicing cardiologists to use. Guidelines should be condensed and their format upgraded, so that the key messages are easier to comprehend and can be applied more readily by those involved in patient care.

Prognostic Significance of Heart Rate Variability Among Patients Treated With Cardiac Resynchronization Therapy: MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy).

Objectives: This study sought to evaluate the prognostic value of heart rate variability (HRV) for death or heart failure in patients with mildly symptomatic heart failure undergoing cardiac resynchronization therapy with a defibrillator (CRT-D).

Background: There are limited data regarding the prognostic value of HRV as a means of identifying high-risk patients treated with CRT-D.

Methods: We analyzed the relationship between pre-implant time-domain (SD of all normal-to-normal RR intervals [SDNN], SDs of averaged 5-min normal-to-normal RR intervals, root mean square of successive differences, and mean of the SDs of all normal-to-normal RR intervals for all 5-min segments of the entire recording), and frequency-domain (low-frequency power, very-low-frequency power [VLF], high-frequency power, low-frequency power/low-frequency power ratio) HRV parameters, and the end point of death or heart failure and death alone.

Mutations in Danish patients with long QT syndrome and the identification of a large founder family with p.F29L in KCNH2.

Background: Long QT syndrome (LQTS) is a cardiac ion channelopathy which presents clinically with palpitations, syncope or sudden death. More than 700 LQTS-causing mutations have been identified in 13 genes, all of which encode proteins involved in the execution of the cardiac action potential. The most frequently affected genes, covering > 90% of cases, are KCNQ1, KCNH2 and SCN5A.

Flecainide provocation reveals concealed brugada syndrome in a long QT syndrome family with a novel L1786Q mutation in SCN5A.

Background: Mutations in SCN5A can result in both long QT type 3 (LQT3) and Brugada syndrome (BrS), and a few mutations have been found to have an overlapping phenotype. Long QT syndrome is characterized by prolonged QT interval, and a prerequisite for a BrS diagnosis is ST elevation in the right precordial leads of the electrocardiogram.

Methods And Results: In a Danish family suffering from long QT syndrome, a novel missense mutation in SCN5A, changing a leucine residue into a glutamine residue at position 1786 (L1786Q), was found to be present in heterozygous form co-segregating with prolonged QT interval.

New-onset atrial fibrillation predicts malignant arrhythmias in post-myocardial infarction patients--a Cardiac Arrhythmias and RIsk Stratification after acute Myocardial infarction (CARISMA) substudy.

Background: After myocardial infarction (MI) the risk of sudden cardiac death due to arrhythmias is substantial.

Objective: The purpose of this study was to investigate if new-onset atrial fibrillation (AF) is associated with development of potential malignant brady- and tachyarrhythmias after an acute MI.

Methods: The study included 277 post-MI patients from the CARISMA study with left ventricular ejection fraction ≤ 40%, New York Heart Association class I, II, or III and no history of AF.

Impact of the right ventricular lead position on clinical outcome and on the incidence of ventricular tachyarrhythmias in patients with CRT-D.

Background: Data on the impact of right ventricular (RV) lead location on clinical outcome and ventricular tachyarrhythmias in cardiac resynchronization therapy with defibrillator (CRT-D) patients are limited.

Objective: To evaluate the impact of different RV lead locations on clinical outcome in CRT-D patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy trial.

Methods: We investigated 742 of 1089 CRT-D patients (68%) with adjudicated RV lead location enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy trial to evaluate the impact of RV lead location on cardiac events.

Long-term recording of cardiac arrhythmias with an implantable cardiac monitor in patients with reduced ejection fraction after acute myocardial infarction: the Cardiac Arrhythmias and Risk Stratification After Acute Myocardial Infarction (CARISMA) study.

Background: Knowledge about the incidence of cardiac arrhythmias after acute myocardial infarction has been limited by the lack of traditional ECG recording systems to document and confirm asymptomatic and symptomatic arrhythmias. The Cardiac Arrhythmias and Risk Stratification After Myocardial Infarction (CARISMA) trial was designed to study the incidence and prognostic significance of arrhythmias documented by an implantable cardiac monitor among patients with acute myocardial infarction and reduced left ventricular ejection fraction.

Methods And Results: A total of 1393 of 5869 patients (24%) screened in the acute phase (3 to 21 days) of an acute myocardial infarction had left ventricular ejection fraction ≤40%.

Echocardiographic effects of changing atrioventricular delay in cardiac resynchronization therapy based on displacement.

Background: In studies showing benefits of cardiac resynchronization therapy (CRT), individual atrioventricular (AV) delays have been optimized using echocardiography. However, the method for AV delay optimization remains controversial.

Methods: In 100 consecutive patients with CRT device implantation, AV delay was optimized using echocardiography.

The role of local voltage potentials in outflow tract ectopy.

Aims: Discrete, fragmented, local voltage potentials (LVPs) have been observed in electrograms recorded at the ablation site in patients undergoing radiofrequency ablation for arrhythmias originating in both the right and left ventricular outflow tract; however, the incidence and the significance of the LVP with respect to arrhythmogenesis is uncertain.

Methods And Results: We studied 25 patients with outflow tract arrhythmias referred for radiofrequency catheter ablation and recorded high-amplified intracardiac electrograms close to the site of origin of the arrhythmia. Ten patients undergoing ablation for supraventricular arrhythmias served as controls.

Improved arrhythmia detection in implantable loop recorders.

Introduction: Implantable loop recorders (ILR) have an automatic arrhythmia detection feature that can be compromised by inappropriately detected episodes. This study evaluated a new ILR sensing and detection scheme for automatically detecting asystole, bradyarrhythmia, and tachyarrhythmia events, which is implemented in the next generation device (Reveal DX/XT).

Methods And Results: The new scheme employs an automatically adjusting R-wave sensing threshold, enhanced noise rejection, and algorithms to detect asystole, bradyarrhythmia, and tachyarrhythmia.

Long QT syndrome genotyping by electrocardiography: fact, fiction, or something in between?

Diagnosis of long QT syndrome (LQTS) is difficult. A prolonged QT interval is easily overlooked, and in 10% of all patients with LQTS, the QT interval is normal. Genotyping is unfortunately not able to detect all patients and healthy subjects correctly.

Phase 2 reentry in man.

Background: Ventricular extrasystoles are characterized by a fixed coupling interval to the last QRST complex preceding it.

Objectives: We hypothesized that this QRST complex differed from QRST complexes of other sinus beats not followed by ventricular extrasystoles. Further, we investigated whether phase 2 reentry, demonstrated in animal experiments to initiate ventricular extrasystoles, ventricular tachycardia, and ventricular fibrillation, also plays a role in humans.

T wave morphology analysis distinguishes between KvLQT1 and HERG mutations in long QT syndrome.

Objectives: The aim of this study was to develop an objective method to distinguish between HERG and KvLQT1 genotypes on the surface ECG.

Background: The two most prevalent genes affected in long QT syndrome (LQTS) are KvLQT1 (KCNQ1) and HERG (KCNH2), which are mutated in >90% of patients with a reported LQTS genotype. It is known that T waves have lower amplitude and more notches in HERG patients than T waves in KvLQT1 patients, but this semiquantitative method lacks the discriminative power to be used in a clinical setting.