Sam Riahi

Validity of the diagnoses atrial fibrillation and atrial flutter in a Danish patient registry

Objectives. To assess the validity of the diagnoses of atrial fibrillation (AF) and atrial flutter (AFL) for men and women recorded in the Danish National Patient Registry, and to assess the relative distribution of AF and AFL. Design. Review of medical records for incident cases of AF and/or AFL in the Diet, Cancer, and Health cohort study. Participants were enrolled in 1993–97 with 13.6 years of follow-up until 30 December, 2009. Results. The positive predictive value of the combined diagnosis of AF and/or AFL was 92.6% (95% CI 88.8%; 95.2%) with no significant difference between sexes (men 93.7% (133/142), women 90.8% (129/142)). The proportion of AFL either alone or in combination with AF was significantly higher in men than in women (13.5% (18/133) vs. 5.4% (7/129), p =0.03). The positive predictive value of the specified diagnosis of AFL was 57.5% for men (46/80) and 29.6% for women (8/27). Conclusions. This study shows that the validity of the diagnosis of AF and/or AFL is high and may be used for registry-based studies. A specified diagnosis of AFL was rarely used and was not reliable to distinguish between cases of AF and AFL.

The Atrial Fibrillation Ablation Pilot Study: an European Survey on Methodology and results of catheter ablation for atrial fibrillation conducted by the European Heart Rhythm Association

AIMS The Atrial Fibrillation Ablation Pilot Study is a prospective registry designed to describe the clinical epidemiology of patients undergoing an atrial fibrillation (AFib) ablation, and the diagnostic/therapeutic processes applied across Europe. The aims of the 1-year follow-up were to analyse how centres assess in routine clinical practice the success of the procedure and to evaluate the success rate and long-term safety/complications. METHODS AND RESULTS Seventy-two centres in 10 European countries were asked to enrol 20 consecutive patients undergoing a first AFib ablation procedure. A web-based case report form captured information on pre-procedural, procedural, and 1-year follow-up data. Between October 2010 and May 2011, 1410 patients were included and 1391 underwent an AFib ablation (98.7%). A total of 1300 patients (93.5%) completed a follow-up control 367 ± 42 days after the procedure. Arrhythmia documentation was done by an electrocardiogram in 76%, Holter-monitoring in 52%, transtelephonic monitoring in 8%, and/or implanted systems in 4.5%. Over 50% became asymptomatic. Twenty-one per cent were re-admitted due to post-ablation arrhythmias. Success without antiarrhythmic drugs was achieved in 40.7% of patients (43.7% in paroxysmal AF; 30.2% in persistent AF; 36.7% in long-lasting persistent AF). A second ablation was required in 18% of the cases and 43.4% were under antiarrhythmic treatment. Thirty-three patients (2.5%) suffered an adverse event, 272 (21%) experienced a left atrial tachycardia, and 4 patients died (1 haemorrhagic stroke, 1 ventricular fibrillation in a patient with ischaemic heart disease, 1 cancer, and 1 of unknown cause). CONCLUSION The AFib Ablation Pilot Study provided crucial information on the epidemiology, management, and outcomes of catheter ablation of AFib in a real-world setting. The methods used to assess the success of the procedure appeared at least suboptimal. Even in this context, the 12-month success rate appears to be somewhat lower to the one reported clinical trials.

Atrial fibrillation in patients with sick sinus syndrome: the association with PQ-interval and percentage of ventricular pacing

AIMS In the recently published DANPACE trial, incidence of atrial fibrillation (AF) was significantly higher with single-lead atrial (AAIR) pacing than with dual-chamber (DDDR) pacing. The present analysis aimed to evaluate the importance of baseline PQ-interval and percentage of ventricular pacing (VP) on AF. METHODS AND RESULTS We analysed data on AF during follow-up in 1415 patients included in the DANPACE trial. In a subgroup of 650 patients with DDDR pacemaker, we studied whether %VP, baseline PQ-interval, and programmed atrio-ventricular interval (AVI) was associated with AF burden measured as time in mode-switch (MS) detected by the pacemaker. In the entire DANPACE study population, the incidence of AF was significantly higher in patients with baseline PQ-interval >180 ms (P< 0.001). Among 650 patients with DDDR pacemaker, telemetry data were available for 1.337 ± 786 days, %VP was 66 ± 33%, AF was detected at planned follow-up in 160 patients (24.6%), MS occurred in 422 patients (64.9%), and AF burden was marginally higher with baseline PQ-interval >180 ms (P= 0.028). No significant association was detected between %VP and %MS (Spearmans ρ 0.056, P= 0.154). %MS was not different between minimal-paced programmed AVI ≤ 100 and >100 ms (median value), respectively (P= 0.60). CONCLUSIONS The present study indicates that a longer baseline PQ-interval is associated with an increased risk of AF in patients with sick sinus syndrome. Atrial fibrillation burden is not associated with the percentage of VP or the length of the programmed AVI.

Marine n-3 fatty acids: basic features and background.

There is some evidence from epidemiology that intake of n-3 polyunsaturated fatty acids (PUFA) from seafood may protect against coronary artery disease (CAD). This hypothesis is further supported from animal data showing a beneficial effect of n-3 PUFA on thrombosis and atherosclerosis in animals fed fish oils in most, but not all, studies. There are several mechanisms by which an increased intake of marine n-3 PUFA may protect against CAD; the most universal finding is a reduction of plasma triglycerides. It is puzzling, however, that a very low amount of n-3 PUFA, with no known beneficial biochemical effects, seems to be cardioprotective. It has therefore been of paramount interest to perform clinical trials. Such evidence and trials are discussed in later chapters, and the results have been very encouraging.

Risk of Device Malfunction in Cancer Patients with Implantable Cardiac Device Undergoing Radiotherapy: A Population‐Based Cohort Study

Pacemakers (PMs) and implantable cardioverter defibrillators (ICDs) may develop malfunction during external beam radiotherapy (RT). We aimed to describe clinical practice in PM/ICD patients undergoing RT and to assess the rate and predictors of device malfunctions.

A U-shaped association between consumption of marine n-3 fatty acids and development of atrial fibrillation/atrial flutter—a Danish cohort study

AIMS Previous studies have suggested a lower risk of atrial fibrillation (AF) with higher intakes of fish and marine n-3 polyunsaturated fatty acids (PUFAs), but the results have been inconsistent. The aim was to investigate the association between consumption of marine n-3 PUFA and development of AF. METHODS AND RESULTS A total of 57 053 Danish participants 50-64 years of age were enrolled in the Diet, Cancer, and Health Cohort Study between 1993 and 1997. Dietary intake of fish and marine n-3 PUFA was assessed by a semi-quantitative food frequency questionnaire. In total, 3345 incident cases of AF occurred over 13.6 years. Multivariate Cox regression analyses (3284 cases and 55 246 participants) using cubic splines showed a U-shaped association between consumption of marine n-3 PUFA and risk of incident AF, with the lowest risk of AF at a moderate intake of 0.63 g/day. For quintiles of marine n-3 PUFA intake, a 13% statistically significant lower risk of AF was seen in the middle vs. lowest quintile: Q1 reference, Q2 HR 0.92 (95% CI 0.82-1.03), Q3 HR 0.87 (95% CI 0.78-0.98), Q4 HR 0.96 (95% CI 0.86-1.08), and Q5 HR 1.05 (95% CI 0.93-1.18). Intake of total fish, fatty fish, and the individual n-3 PUFA eicosapentaenoic acid, docosahexaenoic acid, and docosapentaenoic acid also showed U-shaped associations with incident AF. CONCLUSION We found a U-shaped association between consumption of marine n-3 PUFA and risk of incident AF, with the lowest risk close to the median intake of total marine n-3 PUFA (0.63 g/day).

Nationwide fluoroscopic screening of recalled riata defibrillator leads in Denmark

BACKGROUND The natural history of insulation defects with inside-out conductor externalization in recalled St Jude Medical Riata defibrillator leads is not well understood. OBJECTIVES To determine the prevalence of externalization in a nationwide screening. Secondary aims were to examine time dependence and location of externalization, association with electrical failure, and fluoroscopic diagnostic performance. METHODS All 299 patients with recalled Riata leads in Denmark were identified, and all except one underwent fluoroscopy and device interrogation. Externalizations were confirmed by multiple investigators. RESULTS The prevalence of externalization was 32 of 298 (11%) at a mean dwell time of 5.1 years. The prevalence was 21 of 98 (21%) for 8-F leads and 11 of 200 (6%) for 7-F leads; however, 8-F leads had longer dwell times. The degree of externalization was correlated with dwell time (Spearmans ρ = .37; P = .03). Externalization more often included the lead segment below the tricuspid annulus in dual coil leads than in single coil leads (69% vs 16%; P = .004). No association was observed between externalization and electrical function. Fluoroscopic diagnostic performance was good with positive and negative predictive values of 88% and 99%, respectively. CONCLUSIONS The prevalence of externalization in a nationwide screening is at the same level as reported in previous studies with similar lead dwell times. The degree of externalization is time dependent, and location seems to differ between single and dual coil leads. Long-term lead performance and association with electrical failure need further clarification. Fluoroscopy has a good diagnostic performance in clinical practice.

The effect of radiotherapy beam energy on modern cardiac devices: an in vitro study.

AIMS Radiotherapy (RT) for malignancies can harm pacemakers (PMs) and implantable cardioverter-defibrillators (ICDs). There is some evidence that, besides cumulative dose, the damaging radiation effects increase with beam energy. The aim of this study was to determine whether modern PMs and ICDs are more sensitive to high-energy than to low-energy photon beams. METHODS AND RESULTS Two groups of unused PMs and explanted ICDs (five PMs and one ICD in each) were subjected to irradiations in a phantom with 6 and 18 megavolt (MV) photons, respectively. The devices were exposed to radiation at doses of 2 gray (Gy) daily to simulate two clinical scenarios with the PM/ICD in the RT field. A cumulative dose of 150 Gy was given to each device, corresponding to approximately twice the therapeutic dose. In the 6 MV group, one episode of PM malfunction was detected after reaching 150 Gy. In the 18 MV group, a total of 14 episodes of malfunction were detected starting at 30 Gy in all five PMs. No episodes appeared in the ICD, at the respective treatment groups. This corresponded to a hazard ratio of 9.11 [∼95% confidence interval (CI): 1.04-79.69] by Cox regression analysis between the two groups. In a repeated measures logistic regression model comparing the incidence rate of malfunctions, the odds ratio was 18.29 (∼95% CI: 1.52-219.41). CONCLUSION Photon beam energy plays a considerable role in inducing implantable cardiac device malfunctions. Low-energy RT may be safer in PM/ICD patients despite relatively high radiation dose to the device.

Statins, Ventricular Arrhythmias and Heart Rate Variability in Patients with Implantable Cardioverter Defibrillators and Coronary Heart Disease

The aim of this study was to evaluate whether the incidence of ventricular arrhythmias and heart rate variability were influenced by statin treatment and lipid levels in patients treated with an implantable cardioverter defibrillator (ICD). Heart rate variability measurements were performed in 86 patients with coronary heart disease and an ICD implant. The number of events with ventricular fibrillation and ventricular tachycardia were recorded during a 12-month period. This study lends little support for an antiarrhythmic effect of statins or any relation between plasma lipids and lipoproteins and malignant ventricular arrhythmias in patients with an ICD.

Marine n-3 fatty acids in adipose tissue and development of atrial fibrillation: a Danish cohort study

Objective Consumption of fish and marine n-3 polyunsaturated fatty acids (PUFA) may be associated with a lower risk of atrial fibrillation (AF), but results have been inconsistent. The aim was to investigate this further by measurements of marine n-3 PUFA in adipose tissue. Design Cohort study. Setting A total of 57 053 Danish participants 50–64 years of age were enrolled into the Diet, Cancer and Health Cohort Study. Patients A randomly drawn subcohort of 3440 participants with available data from baseline adipose tissue biopsies. Interventions Exposure was the adipose tissue content of marine n-3 PUFA, which reflects the endogenous exposure and is also an objective marker of the long-term dietary intake. Main outcome measures Incident AF during follow-up. Results 179 cases of AF occurred over 13.6 years. Multivariate, sex-stratified Cox proportional hazards regression analyses using cubic splines showed a monotonic, negative, dose-response trend, but not statistically significant association, between total marine n-3 PUFA in adipose tissue and incident AF. A similar trend towards a lower risk of AF was seen in the second (HR 0.87, 95% CI 0.60 to 1.24) and third tertiles (HR 0.77, 95% CI 0.53 to 1.10) of marine n-3 PUFA compared with the lowest tertile. Similar trends, but also not statistically significant, were found separately for eicosapentaenoic, docosahexaenoic and docosapentaenoic acids. Conclusions There was no statistically significant association between the content of marine n-3 PUFA in adipose tissue and the development of AF; however, data showed a monotonic, negative dose-response trend suggestive of a negative association.