Overdrive pacing of early ischemic ventricular tachycardia: evidence for both reentry and triggered activity

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldEntrainment can be a useful method to identify reentry as a mechanism of ventricular tachycardia (VT). In this study, we evaluated the effect of gradually decreasing cycle lengths of overdrive pacing for stable VT induced in a canine model 1-3 h after coronary occlusion. Intact dogs underwent anterior descending coronary artery occlusion after instrumentation of the risk zone with 21 multipolar plunge needles, each recording 6 bipolar electrograms. Overdrive pacing was attempted if the animals had sustained hemodynamically stable VT, looking for evidence of entrainment. Subsequent three-dimensional mapping determined the mechanism of VT. Fifteen of the 21 dogs studied demonstrated entrainment with overdrive pacing by progressive QRS fusion alone (1), the first nonpaced QRS entrained to the paced cycle length only (7), or both (7). Five of these 15 dogs also had postpacing acceleration of the VT at a subsequent faster pacing cycle length. The mechanism of acceleration in four was a change to a VT with a focal origin. The prepacing mechanism in all 15 dogs was subsequently mapped to reentry. Regarding the six VTs, which demonstrated no evidence for entrainment, the site of earliest activity was mapped to a focal origin in all. These data showing entrainment of inducible reentrant VTs and lack of such for focal VTs support that the focal VTs seen in this study are unlikely the result of microreentry but possibly a mechanism as triggered activity

Familial aggregation of atrial fibrillation in Iceland

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldAIMS: To examine the heritability of atrial fibrillation (AF) in Icelanders, utilizing a nationwide genealogy database and population-based data on AF. AF is a disorder with a high prevalence, which has been known to cluster in families, but the heritability of the common form has not been well defined. METHODS AND RESULTS: The study population included 5269 patients diagnosed since 1987 and age-sex-matched controls randomly selected from the genealogy database. Kinship coefficients (KC), expressed as genealogical index of familiality (GIF = average KC x 100,000), were calculated before and after exclusion of relatives separated by one to five meiotic events. Risk ratios (RR) were calculated for first- to fifth-degree relatives. The average pairwise GIF among patients with AF was 15.9 (mean GIF for controls 13.9, 95%CI = 13.3, 14.4); this declined to 15.4 (mean GIF for controls 13.6, 95%CI = 13.1, 14.2) after exclusion of relatives separated by one meiosis and to 13.7 (mean GIF for controls 12.6, 95%CI = 12.1, 13.2), 12.7 (mean GIF for controls 11.9, 95%CI = 11.4, 12.4), and 11.3 (mean GIF for controls 10.6, 95%CI = 10.1, 11.1) after exclusion of relatives within two, three, and four meioses, respectively (all P<0.00001). RRs among relative pairs also declined incrementally, from 1.77 in first-degree relatives to 1.36, 1.18, 1.10, and 1.05 in second- through fifth-degree relatives (all P<0.001), consistent with the declining proportion of alleles shared identically by descent. When the analysis was limited to subjects diagnosed with AF before the age of 60, first-degree relatives of the AF cases were nearly five times more likely to have AF than the general population. CONCLUSION: AF shows strong evidence of heritability among unselected patients in Iceland, suggesting that there may be undiscovered genetic variants underlying the risk of the common form of AF

Health-related quality of life of patients with implantable cardioverter defibrillators compared with that of pacemaker recipients

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldAIMS: Studies indicate a poorer quality of life (QoL) for implantable cardioverter defibrillator (ICD) patients than for the general population. However, studies comparing the QoL of ICD patients with that of patients with other implantable cardiac devices are scarce. We hypothesized that ICD patients had a poorer QoL than pacemaker patients. METHODS AND RESULTS: All ICD patients living in Iceland at the beginning of 2002 (44 subjects), and a comparison group of 81 randomly selected patients with pacemakers were invited to participate. The Icelandic Quality of Life Questionnaire (IQL), the General Health Questionnaire (GHQ), the Beck Anxiety Inventory (BAI), and the Beck Depression Inventory (BDI) were submitted to measure QoL, psychiatric distress, and symptoms of anxiety and depression. The ICD and pacemaker groups did not differ on IQL, BAI, BDI, or GHQ scores. ICD patients were as a group more fearful of death (P = 0.056) and showed more concerns about returning to work (P = 0.072), although these items fell just short of statistical significance. CONCLUSION: Contrary to our expectations, ICD patients had a comparable QoL with pacemaker recipients and were not more likely to suffer from anxiety, depression, or general psychiatric distress. These findings are encouraging in view of expanding ICD indications

Does treatment with n-3 polyunsaturated fatty acids prevent atrial fibrillation after open heart surgery?

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldAIMS: To examine the effect of n-3 polyunsaturated fatty acid (PUFA) treatment on the incidence of post-operative atrial fibrillation (POAF). METHODS AND RESULTS: A prospective, randomized, double-blinded, placebo-controlled trial was conducted in patients admitted for coronary artery bypass grafting and/or valvular repair surgery. The patients received either n-3 PUFA capsules, containing a daily dose of 1240 mg eicosapentaenoic acid and 1000 mg docosahexaenoic acid, or olive oil capsules for 5-7 days prior to surgery and post-operatively until hospital discharge. The endpoint was POAF, defined as an episode detected by continuous electrocardiographic monitoring, lasting >5 min. A total of 170 patients were enrolled in the study, and 168 patients underwent surgery. Their median age was 67 (range 43-82) years, and 79.2% were males. There was no difference in baseline characteristics between the n-3 PUFA group (n = 83) and the placebo group (n = 85), and the incidence of POAF was 54.2 and 54.1% (P = 0.99), respectively. Factors associated with POAF included advanced age, peak post-operative C-reactive protein level, valvular surgery, lower body mass index, and non-smoking, but n-3 PUFA concentration in plasma lipids was not associated with POAF. CONCLUSION: There is no evidence for a beneficial effect of treatment with n-3 PUFA on the occurrence of POAF in patients undergoing open heart surgery

Atrial fibrillation is associated with reduced brain volume and cognitive function independent of cerebral infarcts.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked Files. This article is open access.Atrial fibrillation (AF) has been associated with cognitive decline independent of stroke, suggesting additional effects of AF on the brain. We aimed to assess the association between AF and brain function and structure in a general elderly population.This is a cross-sectional analysis of 4251 nondemented participants (mean age, 76 ± 5 years) in the population-based Age, Gene/Environment Susceptibility-Reykjavik Study. Medical record data were collected for the presence, subtype, and time from first diagnosis of AF; 330 participants had AF. Brain volume measurements, adjusted for intracranial volume, and presence of cerebral infarcts were determined with magnetic resonance imaging. Memory, speed of processing, and executive function composites were calculated from a cognitive test battery. In a multivariable linear regression model, adjustments were made for demographic factors, cardiovascular risk factors, and cerebral infarcts.Participants with AF had lower total brain volume compared with those without AF (P<0.001). The association was stronger with persistent/permanent than paroxysmal AF and with increased time from the first diagnosis of the disease. Of the brain tissue volumes, AF was associated with lower volume of gray and white matter hyperintensities (P<0.001 and P = 0.008, respectively), but not of white matter hyperintensities (P = 0.49). Participants with AF scored lower on tests of memory.AF is associated with smaller brain volume, and the association is stronger with increasing burden of the arrhythmia. These findings suggest that AF has a cumulative negative effect on the brain independent of cerebral infarcts.Landspitali National University Hospital of Iceland Science Fund Helga Jonsdottir and Sigvaldi Kristjansson Memorial Fund National Institutes of Health/N01-AG-1-2100 National Institute on Aging Intramural Research Program Icelandic Heart Association Althingi (the Icelandic Parliament

Sequence variant at 4q25 near PITX2 associates with appendicitis.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked FilesAppendicitis is one of the most common conditions requiring acute surgery and can pose a threat to the lives of affected individuals. We performed a genome-wide association study of appendicitis in 7,276 Icelandic and 1,139 Dutch cases and large groups of controls. In a combined analysis of the Icelandic and Dutch data, we detected a single signal represented by an intergenic variant rs2129979 [G] close to the gene PITX2 associating with increased risk of appendicitis (OR = 1.15, P = 1.8 × 10(-11)). We only observe the association in patients diagnosed in adulthood. The marker is close to, but distinct from, a set of markers reported to associate with atrial fibrillation, which have been linked to PITX2. PITX2 has been implicated in determination of right-left symmetry during development. Anomalies in organ arrangement have been linked to increased prevalence of gastrointestinal and intra-abdominal complications, which may explain the effect of rs2129979 on appendicitis risk

Management of asymptomatic arrhythmias: a European Heart Rhythm Association (EHRA) consensus document, endorsed by the Heart Failure Association (HFA), Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS), Cardiac Arrhythmia Society of Southern Africa (CASSA), and Latin America Heart Rhythm Society (LAHRS).

Asymptomatic arrhythmias are frequently encountered in clinical practice. Although studies specifically dedicated to these asymptomatic arrhythmias are lacking, many arrhythmias still require proper diagnostic and prognostic evaluation and treatment to avoid severe consequences, such as stroke or systemic emboli, heart failure, or sudden cardiac death. The present document reviews the evidence, where available, and attempts to reach a consensus, where evidence is insufficient or conflicting

2018 EHRA expert consensus statement on lead extraction: Recommendations on definitions, endpoints, research trial design, and data collection requirements for clinical scientific studies and registries: Endorsed by APHRS/HRS/LAHRS

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The use of implantable cardioverter defibrillators in Iceland: a retrospective population based study

BACKGROUND: Indications for implantable cardioverter defibrillator (ICD) implantation have expanded considerably in recent years, resulting in steadily growing numbers of ICD recipients worldwide. The aim of this study was to review the overall experience with ICDs in Iceland. METHODS: This was a retrospective single centre study set at the University Hospital in Iceland. Data on all ICD implantations in Iceland from the first implantation in 1992 till the end of 2002 was reviewed. RESULTS: Sixty-two patients (71% male) received an ICD during this period. There was an increase in the number of implants by year and the number of new implants in 2001 and 2002 amounted to 56 and 38 per million, respectively. The mean age at implantation was 58 (+/-14) years. Forty patients (65%) had coronary artery disease. The most common indications for ICD implantation were cardiac arrest, 32 (52%) and another 26 (42%) had experienced ventricular tachycardia without cardiac arrest. The most common adverse event was inappropriate shocks. Twenty-eight patients (45%) received therapy from their ICDs, with the majority receiving appropriate therapy. Of the thirteen patients deceased before or during the study period, no case of sudden arrhythmic death was observed. CONCLUSION: This study shows that the experience with ICDs in Iceland is in most respects similar to other Western countries

Genetic association study of QT interval highlights role for calcium signaling pathways in myocardial repolarization.

The QT interval, an electrocardiographic measure reflecting myocardial repolarization, is a heritable trait. QT prolongation is a risk factor for ventricular arrhythmias and sudden cardiac death (SCD) and could indicate the presence of the potentially lethal mendelian long-QT syndrome (LQTS). Using a genome-wide association and replication study in up to 100,000 individuals, we identified 35 common variant loci associated with QT interval that collectively explain ∼8-10% of QT-interval variation and highlight the importance of calcium regulation in myocardial repolarization. Rare variant analysis of 6 new QT interval-associated loci in 298 unrelated probands with LQTS identified coding variants not found in controls but of uncertain causality and therefore requiring validation. Several newly identified loci encode proteins that physically interact with other recognized repolarization proteins. Our integration of common variant association, expression and orthogonal protein-protein interaction screens provides new insights into cardiac electrophysiology and identifies new candidate genes for ventricular arrhythmias, LQTS and SCD