Anna Margrethe Thøgersen

High Plasminogen Activator Inhibitor and Tissue Plasminogen Activator Levels in Plasma Precede a First Acute Myocardial Infarction in Both Men and Women Evidence for the Fibrinolytic System as an Independent Primary Risk Factor

BACKGROUND In patients with established ischemic heart disease, prospective cohort studies have indicated that plasminogen activator inhibitor (PAI-1), the inhibitor of the fibrinolytic system, may predict cardiovascular events. So far, there have been no primary prospective studies of PAI-1. METHODS AND RESULTS The aim of the present study was to test whether plasma levels of PAI-1, tissue-type plasminogen activator (tPA), von Willebrand factor (vWF), and thrombomodulin (TM) could predict the occurrence of a first acute myocardial infarction (AMI) in a population with high prevalence of coronary heart disease by use of a prospective nested case-control design. Mass concentrations of PAI-1 and tPA were significantly higher for the 78 subjects who developed a first AMI compared with the 156 references matched for age, sex, and sampling time; for tPA, this increase was independent of smoking habits, body mass index, hypertension, diabetes, cholesterol, and apolipoprotein A-I. The ratio of quartile 4 to 1 for tPA was 5.9 for a patient to develop a first AMI. The association between tPA and AMI was seen in both men and women. Increased levels of vWF were associated with AMI in a univariate analysis. High levels of TM were associated with AMI in women but not in men. CONCLUSIONS The plasma levels of PAI-1, tPA, and vWF are associated with subsequent development of a first AMI; for PAI-1 and tPA, this relation was found in both men and women. For tPA but not for PAI-1 and vWF, this association is independent of established risk factors.

Defibrillator Implantation in Patients with Nonischemic Systolic Heart Failure

BACKGROUND The benefit of an implantable cardioverter-defibrillator (ICD) in patients with symptomatic systolic heart failure caused by coronary artery disease has been well documented. However, the evidence for a benefit of prophylactic ICDs in patients with systolic heart failure that is not due to coronary artery disease has been based primarily on subgroup analyses. The management of heart failure has improved since the landmark ICD trials, and many patients now receive cardiac resynchronization therapy (CRT). METHODS In a randomized, controlled trial, 556 patients with symptomatic systolic heart failure (left ventricular ejection fraction, ≤35%) not caused by coronary artery disease were assigned to receive an ICD, and 560 patients were assigned to receive usual clinical care (control group). In both groups, 58% of the patients received CRT. The primary outcome of the trial was death from any cause. The secondary outcomes were sudden cardiac death and cardiovascular death. RESULTS After a median follow-up period of 67.6 months, the primary outcome had occurred in 120 patients (21.6%) in the ICD group and in 131 patients (23.4%) in the control group (hazard ratio, 0.87; 95% confidence interval [CI], 0.68 to 1.12; P=0.28). Sudden cardiac death occurred in 24 patients (4.3%) in the ICD group and in 46 patients (8.2%) in the control group (hazard ratio, 0.50; 95% CI, 0.31 to 0.82; P=0.005). Device infection occurred in 27 patients (4.9%) in the ICD group and in 20 patients (3.6%) in the control group (P=0.29). CONCLUSIONS In this trial, prophylactic ICD implantation in patients with symptomatic systolic heart failure not caused by coronary artery disease was not associated with a significantly lower long-term rate of death from any cause than was usual clinical care. (Funded by Medtronic and others; DANISH ClinicalTrials.gov number, NCT00542945 .).

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.

Homozygosity for the C677--gT mutation of 5,10-methylenetetrahydrofolate reductase and total plasma homocyst(e) ine are not associated with greater than normal risk of a first myocardial infarction in northern Sweden

BackgroundResults of several case–control studies have shown elevated total plasma homocyst(e)ine (TPH) and homozygosity for the point mutation C 677 →T in the gene for 5,10‐methylenetetrahydrofolate reductase (MTHFR) to be associated with a greater than normal risk of atherosclerotic vascular disease. However, there have been few epidemiologic studies and the interpretation of the results is not clear‐cut. ObjectiveTo elucidate whether homozygosity for the point mutation C 677 →T in the gene for MTHFR, and TPH are risk factors for a first myocardial infarction. DesignA prospective nested case–control study in Northern Sweden. MethodsAmong more than 36 000 persons screened, 78 cases satisfied the inclusion criterion of having developed, after sampling, a first myocardial infarction. For each case, two controls matched for sex and age were randomly selected. ResultsWe found no statistically significant difference among the prevalences of the three possible MTHFR genotypes –/– (no mutation), +/+ (both alleles have the mutation), and +/– among cases and controls in univariate conditional logistic regression analysis. Mean levels of TPH in patients and controls were 12.2 ± 4.9 and 12.2 ± 3.5  μmol/l (means ± SD), respectively (NS). ConclusionsIn this study neither homozygosity for the point mutation C 677 →T in the gene for MTHFR nor TPH was related to a greater than normal risk of a first myocardial infarction for members of the population of northern Sweden. Further research is needed in order to show whether TPH is an independent risk factor for a first myocardial infarction.

Age and Outcomes of Primary Prevention Implantable Cardioverter-Defibrillators in Patients With Nonischemic Systolic Heart Failure

Background: The DANISH study (Danish Study to Assess the Efficacy of ICDs [Implantable Cardioverter Defibrillators] in Patients With Non-Ischemic Systolic Heart Failure on Mortality) did not demonstrate an overall effect on all-cause mortality with ICD implantation. However, the prespecified subgroup analysis suggested a possible age-dependent association between ICD implantation and mortality with survival benefit seen only in the youngest patients. The nature of this relationship between age and outcome of a primary prevention ICD in patients with nonischemic systolic heart failure warrants further investigation. Methods: All 1116 patients from the DANISH study were included in this prespecified subgroup analysis. We assessed the relationship between ICD implantation and mortality by age, and an optimal age cutoff was estimated nonparametrically with selection impact curves. Modes of death were divided into sudden cardiac death and nonsudden death and compared between patients younger and older than this age cutoff with the use of &khgr;2 analysis. Results: Median age of the study population was 63 years (range, 21–84 years). There was a linearly decreasing relationship between ICD and mortality with age (hazard ratio [HR], 1.03; 95% confidence interval [CI], 1.003–1.06; P=0.03). An optimal age cutoff for ICD implantation was present at ⩽70 years. There was an association between reduced all-cause mortality and ICD in patients ⩽70 years of age (HR, 0.70; 95% CI, 0.51–0.96; P=0.03) but not in patients >70 years of age (HR, 1.05; 95% CI, 0.68–1.62; P=0.84). For patients ⩽70 years old, the sudden cardiac death rate was 1.8 (95% CI, 1.3–2.5) and nonsudden death rate was 2.7 (95% CI, 2.1–3.5) events per 100 patient-years, whereas for patients >70 years old, the sudden cardiac death rate was 1.6 (95% CI, 0.8–3.2) and nonsudden death rate was 5.4 (95% CI, 3.7–7.8) events per 100 patient-years. This difference in modes of death between the 2 age groups was statistically significant (P=0.01). Conclusions: In patients with systolic heart failure not caused by ischemic heart disease, the association between the ICD and survival decreased linearly with increasing age. In this study population, an age cutoff for ICD implantation at ⩽70 years yielded the highest survival for the population as a whole. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00542945.

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.

Radiotherapy in patients with pacemakers and implantable cardioverter defibrillators: a literature review

An increasing number of patients with implantable cardiac rhythm devices undergo radiotherapy (RT) for cancer and are thereby exposed to the risk of device failure. Current safety recommendations seem to have limitations by not accounting for the risk of pacemakers and implantable cardioverter defibrillators malfunctioning at low radiation doses. Besides scant knowledge about optimal safety measures, only little is known about the exact prevalence of patients with devices undergoing RT. In this review, we provide a short overview of the principles of RT and present the current evidence on the predictors and mechanisms of device malfunctions during RT. We also summarize practical recommendations from recent publications and from the industry. Strongly associated with beam energy of photon RT, device malfunctions occur at ∼3% of RT courses, posing a substantial issue in clinical practice. Malfunctions described in the literature typically consist of transient software disturbances and only seldom manifest as a permanent damage of the device. Through close cooperation between cardiologists and oncologists, a tailored individualized approach might be necessary in this patient group in waiting time for updated international guidelines in the field.

Intravenous infusion of n -3 polyunsaturated fatty acids and inducibility of ventricular tachycardia in patients with implantable cardioverter defibrillator

AIMS Marine n-3 polyunsaturated fatty acids (PUFA) may have antiarrhythmic effects. The aim of this study was to investigate the effect of intravenously administered n-3 PUFA on the inducibility of ventricular tachycardia (VT) in patients with an implantable cardioverter defibrillator (ICD). METHODS AND RESULTS In a randomized, placebo-controlled cross-over study, patients with an ICD underwent two electrophysiological studies using the stimulation possibilities in the ICD preceded by intravenous infusion of either a lipid emulsion delivering 3.9 g n-3 PUFA or placebo (0.9% saline). The level of stimulation required to induce sustained monomorphic VT was ranked in order from least to most aggressive, and non-inducibility was ranked highest. The content of n-3 PUFA in plasma free fatty acids (FFA), plasma phospholipids, and platelet phospholipids was measured by gas chromatography. Eight patients were included, and six of these completed the study. The content of n-3 PUFA as FFA and in platelet phospholipids increased more after n-3 PUFA infusion than after placebo (P<0.001). Of the five patients who were inducible after placebo, two were no longer inducible after n-3 PUFA infusion and another two required stronger stimulation to induce VT. The difference in the stimulation required after placebo and after n-3 PUFA was borderline significant (P=0.063, Wilcoxon signed-rank test). CONCLUSION Intravenous n-3 PUFA tended to decrease VT inducibility, but a larger study is warranted.

Single-coil and dual-coil defibrillator leads and association with clinical outcomes in a complete Danish nationwide ICD cohort

BACKGROUND The best choice of defibrillator lead in patients with routine implantable cardioverter-defibrillator (ICD) is not settled. Traditionally, most physicians prefer dual-coil leads but the use of single-coil leads is increasing. OBJECTIVE The purpose of this study was to compare clinical outcomes in patients with single- and dual-coil leads. METHODS All 4769 Danish patients 18 years or older with first-time ICD implants from 2007 to 2011 were included from the Danish Pacemaker and ICD Register. Defibrillator leads were 38.9% single-coil leads and 61.1% dual-coil leads. The primary end point was all-cause mortality. Secondary end points were lowest successful energy at implant defibrillation testing, first shock failure in spontaneous arrhythmias, structural lead failure, and lead extraction outcomes. RESULTS Single-coil leads were associated with lower all-cause mortality with an adjusted hazard ratio of 0.85 (95% confidence interval 0.73-0.99; P = .04). This finding was robust in a supplementary propensity score-matched analysis. However, dual-coil leads were used in patients with slightly higher preimplant morbidity, making residual confounding by indication the most likely explanation for the observed association between lead type and mortality. The lowest successful defibrillation energy was higher using single-coil leads (23.2 ± 4.3 J vs 22.1 ± 3.9 J; P < .001). No significant differences were observed for other secondary end points showing high shock efficacies and low rates of lead failures and extraction complications. CONCLUSION Shock efficacy is high for modern ICD systems. The choice between single-coil and dual-coil defibrillator leads is unlikely to have a clinically significant impact on patient outcomes in routine ICD implants.

Prospective nationwide fluoroscopic and electrical longitudinal follow-up of recalled Riata defibrillator leads in Denmark

BACKGROUND Recalled St. Jude Medical Riata defibrillator leads are prone to insulation failures with externalized conductors (ECs). Longitudinal studies are needed to guide lead management. OBJECTIVE The purpose of this study was to describe the dynamic nature of EC and the association with electrical abnormalities and lead extraction outcomes. METHODS A nationwide cohort established in 2012 of 295 patients with recalled Riata leads with dwell time 5.1 ± 1.1 years, 34 ECs, and 19 electrical abnormalities were followed until death, lead discontinuation with fluoroscopy, or a new 2013 screening with fluoroscopy and device interrogation. RESULTS Fluoroscopic follow-up of 239 patients with normal baseline fluoroscopy revealed incident overt EC in 8 leads and borderline EC in 2 leads after 1.1 ± 0.2 years, with an incidence rate of 3.7 per 100 person-years (95% confidence interval 2.0-6.9). Fluoroscopic follow-up in 27 patients with baseline EC showed an increase in EC length of 4 ± 1 mm (P <.001) after 1.1 ± 0.3 years. Electrical follow-up in 276 patients with normal baseline electrical function demonstrated 20 incident electrical abnormalities after 1.0 ± 0.3 years, with an incidence rate of 7.1 per 100 person-years (95% confidence interval 4.6-11.0). This rate was significantly higher in leads with baseline EC, with an adjusted incidence rate ratio of 4.4 (95% confidence interval 1.7-11.5, P = .002). In 15 extractions, all leads were removed, with 2 major complications. CONCLUSION The development of EC is a dynamic process despite long lead dwell time. ECs are associated with a higher risk of electrical abnormalities. Therefore, lead replacement should be considered, especially in patients with a long life expectancy.