M.J. Pekka Raatikainen

Prediction of fatal or near-fatal cardiac arrhythmia events in patients with depressed left ventricular function after an acute myocardial infarction †

Aims To determine whether risk stratification tests can predict serious arrhythmic events after acute myocardial infarction (AMI) in patients with reduced left ventricular ejection fraction (LVEF ≤ 0.40). Methods and results A total of 5869 consecutive patients were screened in 10 European centres, and 312 patients (age 65 ± 11 years) with a mean LVEF of 31 ± 6% were included in the study. Heart rate variability/turbulence, ambient arrhythmias, signal-averaged electrocardiogram (SAECG), T-wave alternans, and programmed electrical stimulation (PES) were performed 6 weeks after AMI. The primary endpoint was ECG-documented ventricular fibrillation or symptomatic sustained ventricular tachycardia (VT). To document these arrhythmic events, the patients received an implantable ECG loop-recorder. There were 25 primary endpoints (8.0%) during the follow-up of 2 years. The strongest predictors of primary endpoint were measures of heart rate variability, e.g. hazard ratio (HR) for reduced very-low frequency component (<5.7 ln ms2) adjusted for clinical variables was 7.0 (95% CI: 2.4–20.3, P < 0.001). Induction of sustained monomorphic VT during PES (adjusted HR = 4.8, 95% CI, 1.7–13.4, P = 0.003) also predicted the primary endpoint. Conclusion Fatal or near-fatal arrhythmias can be predicted by many risk stratification methods, especially by heart rate variability, in patients with reduced LVEF after AMI.

Remote monitoring of implantable cardioverter defibrillator patients: a safe, time-saving, and cost-effective means for follow-up

Aims The purpose of this prospective study was to investigate whether internet-based remote monitoring offers a safe, practical, and cost-effective alternative to the in-office follow-up visits of patients with an implantable cardioverter defibrillator (ICD). Methods and results Forty-one patients (62 ± 10 years, range 41–76, 83% male) with previously implanted ICD were followed for 9 months. One-hundred and nineteen scheduled and 18 unscheduled data transmissions were performed. There were no device-related adverse events. Over 90% of the patients found the system easy to use. Physicians reported the system as being ‘very easy’ or ‘easy’ to use and found the data comparable to traditional device interrogation in 99% of the cases. They were able to address all unscheduled data transmissions remotely. Compared with the in-office visits, remote monitoring required less time from patients (6.9 ± 5.0 vs. 182 ± 148 min, P < 0.001) and physicians (8.4 ± 4.5 vs. 25.8 ± 17.0 min, P < 0.001) to complete the follow-up. Substitution of two routine in-office visits during the study by remote monitoring reduced the overall cost of routine ICD follow-up by 524€ per patient (41%). Conclusion Remote monitoring offers a safe, feasible, time-saving, and cost-effective solution to ICD follow-up.

Prediction of Sudden Cardiac Death Appraisal of the Studies and Methods Assessing the Risk of Sudden Arrhythmic Death

Since the recognition of the high incidence of cardiac arrest as the mechanism of sudden cardiac death (SCD), medical scientists and clinicians have sought methods to predict and prevent these events. Significant progress has already been made in the prediction and prevention of life-threatening arrhythmias during the last decade. This progress is highlighted by the outcomes of 4 recently published randomized studies demonstrating that the implantable cardioverter defibrillator (ICD) provides a mortality benefit compared with conventional drug therapy in highly specific subsets of patients.1–4 In parallel with intervention studies, several observational studies and reports have raised an optimistic notion that arrhythmic death can be predicted by methods potentially useful for widespread screening programs.5–10 Despite the evidence-based data and practical recommendations for indications of ICD therapy,11 utilization of this therapy has not been uniformly implemented worldwide, and screening of patients at potential high risk for arrhythmic death has not become a routine clinical practice. In addition to economic and educational factors, this may be due to methodological problems in the designs of a number of the completed observational and randomized intervention studies that confound the interpretation of the results and general application of the procedures. In this report, we analyze the problems of predicting arrhythmic deaths and the advantages and limitations of the various methods and studies, and we evaluate the need for new and better studies and methods of risk stratification. Three types of clinical research designs have been used to estimate the efficacy of interventions and the accuracy of methods for predicting sudden arrhythmic death: (1) observational follow-up studies, (2) case-control studies, and (3) randomized intervention designs. Observational studies are based on baseline assessment of 1 or more risk variables and subsequent follow-up of predefined patient groups. These studies have been most commonly used in the …

Schizophrenia and sudden cardiac death—A review

Schizophrenia is a devastating mental disorder, which is often associated with severe loss of functioning and shortened life expectancy. Suicides and accidents are well-known causes of the excess mortality, but patients with schizophrenia have also been reported to be three times as likely to experience sudden unexpected death as individuals from the general population. This review is aimed to offer an update of the prevalence and mechanisms for sudden cardiac death in schizophrenia. The PubMed database was searched from 1966 up to May 2007 with key words schizophrenia AND “ sudden cardiac death” OR “autonomic dysfunction” OR “torsades de pointes”. Part of the high death rates may be explained by long-lasting negative health habits, disease- and treatment-related metabolic disorders, and consequent increased frequencies of cardiovascular diseases. The antipsychotic medications may also increase the risk as some antipsychotics may cause prolongation of QT-time, serious ventricular arrhythmias and predispose to sudden death. Autonomic dysfunction seen as low heart rate variability and decreased baroreflex sensitivity may also contribute via malignant arrhythmias. Due to the complex interaction of various risk factors for sudden death, the patients need a comprehensive follow-up of their physical health. In addition, more studies on the role and prevalence of autonomic dysfunction in psychotic patients are needed.

Radiofrequency ablation vs. antiarrhythmic drug therapy as first line treatment of symptomatic atrial fibrillation: systematic review and meta-analysis

AIMS New evidence about first-line radiofrequency catheter ablation (RFA) in symptomatic atrial fibrillation (AF) has emerged. In a single study the comparative treatment effect is potentially diminished by the high rate of cross-over to the alternative therapy. Therefore, we conducted a systematic review and meta-analysis of the available data to further evaluate the efficacy and safety of RFA vs. antiarrhythmic drugs (AADs). METHODS AND RESULTS Five databases were searched for randomized controlled trials comparing RFA and AAD therapy as first-line treatment of AF in August 2014. Three studies with 491 patients with recurrent symptomatic AF were included. The patients were relatively young and the majority of them had paroxysmal AF (98.7%) and no major comorbidity. Radiofrequency catheter ablation was associated with significantly higher freedom from AF recurrence compared with AAD therapy [risk ratio (RR) 0.63, 95% confidence interval (CI) 0.44-0.92, P = 0.02]. The difference in the rate of symptomatic AF recurrences was not statistically significant (RR 0.57, 95% CI 0.30-1.08, P = 0.09). There was one procedure-related death and seven tamponades with RFA, whereas symptomatic bradycardia was more frequent with AAD therapy. CONCLUSION Radiofrequency catheter ablation seems to be more effective than medical therapy as first-line treatment of paroxysmal AF in relatively young and otherwise healthy patients, but may also cause more severe adverse effects. These findings support the use of RFA as first-line therapy in selected patients, who understand the benefits and risks of the procedure.

Heart Rate Turbulence after Ventricular and Atrial Premature Beats in Subjects without Structural Heart Disease

Introduction: Studies assessing heart rate (HR) behavior after premature beats have focused on HR responses to ventricular premature beats (VBPs), but there is less information of HR behavior after atrial premature beats (APBs).

Impaired negative chronotropic response to adenosine in patients with inappropriate sinus tachycardia

Adenosine and Inappropriate Sinus Tachycardia. Introduction: Adenosine is an endogenous nucleoside that has an important role in the diagnosis and treatment of several cardiac arrhythmias. However, its effects on inappropriate sinus tachycardia (IST) are not well established.

Cardiac arrest and left ventricular fibrosis in a Finnish family with the lamin A/C mutation.

Introduction: We screened the candidate genes from a Finnish family in which the mother was resuscitated from ventricular fibrillation and the daughter died suddenly without any prior cardiac symptoms.

Cellular source and role of adenosine in isoproterenol-induced coronary vasodilatation

The role of adenosine and its cellular source in isoproterenol-induced coronary vasodilatation was investigated in isolated perfused rat hearts prelabelled with [3H]adenosine. Time courses (times for half-maximal increase) were measured for changes in oxygen consumption (2.23 +/- 0.22 min), coronary flow (3.30 +/- 0.33 min), concentrations of effluent radioactivity (3.92 +/- 0.30 min) and adenosine and its metabolites (inosine, hypoxanthine and xanthine) (2.00 +/- 0.23 min). Isoproterenol stimulation decreased the cellular energy state and increased the concentration of tissue adenosine and its metabolites. Coronary flow was linearly correlated with tissue adenosine (r = 0.85) and phosphorylation potential (r = -0.82) and tissue adenosine also showed a linear correlation with phosphorylation potential (r = -0.84) and tissue free [AMP] (r = 0.79). The specific radioactivities of tissue nucleotides remained constant, but those of adenosine, inosine and hypoxanthine + xanthine were decreased by 42%, 26% and 46%, respectively. Purine compound concentrations increased during isoproterenol stimulation from basal values of 56 +/- 23, 98 +/- 33 and 44 +/- 19 nM to 388 +/- 173, 583 +/- 156 and 178 +/- 27 nM, respectively. The basal specific radioactivity ratio of adenosine:inosine:(hypoxanthine + xanthine) in the effluent perfusate was 1:0.5:7, but the specific radioactivities decreased rapidly upon isoproterenol stimulation, and at 3 min the ratio had changed to 1:2.5:16.5. The time courses of release and the changes in the specific radioactivities of the nucleosides indicate that adenosine release occurred mainly from cardiomyocytes, and that the release of adenosine and its metabolites from the cardiomyocytes preceded that from the endothelium. It is also shown that adenosine release during catecholamine stimulation occurs concomitantly with a decrease in the cellular energy state and AMP accumulation. This is in accord with the adenosine hypothesis of coronary vasoregulation.

Efflux of adenosine and its catabolites during cold blood cardioplegia

Levels of myocardial high-energy phosphates decrease during cardioplegia for open heart operations, with a subsequent increase in the level of adenosine and its metabolites. It has been demonstrated in experimental models that the effluent concentrations of purines can be used as a measure of the average myocardial energy state. Net adenylate loss and myocardial energy state were evaluated here by determining aorta-coronary sinus differences in levels of adenosine catabolites in 17 patients during cold blood cardioplegia for elective coronary artery bypass grafting. Repeated blood samples were taken before cross-clamping of the aorta, when cardioplegic solute was infused into the aortic root and grafts after five distal anastomoses, and after declamping of the aorta. The aorta-coronary sinus differences in levels of total purines increased 4.7-, 7.5-, 7.1-, 7.8-, and 10.2-fold (from the preclamp level of 1.7 +/- 0.7 mumol/L; p < 0.001) for grafts one through five anastomosed at an average of 19, 34, 50, 63, and 76 minutes after the aortic cross-clamp, respectively. Hypoxanthine and xanthine were present in the highest concentrations. Vasodilatory adenosine concentrations of 1 to 2 mumol/L were observed in the coronary sinus while the aorta was cross-clamped. There was a linear positive correlation between the aorta-coronary sinus purine differences and corresponding cross-clamp time (r = 0.62; p < 0.001). The metabolite differences settled at a more negative level after declamping of the aorta than that prevailing before placement of the cross-clamp, suggesting continuous washout of adenosine and its catabolites during the 30-minute postclamp observation period.(ABSTRACT TRUNCATED AT 250 WORDS)