Increased intra-QRS fragmentation in magnetocardiography as a predictor of arrhythmic events and mortality in patients with cardiac dysfunction after myocardial infarction

Introduction: Increased intra-QRS fragmentation score (FRA) in magnetocardiography (MCG) has shown association with sustained ventricular arrhythmias in post-MI patients suggesting its relation to arrhythmia substrate. The aim of this study was to investigate whether increased FRA in MCG predicts arrhythmic events and mortality after acute myocardial infarction (MI) with cardiac dysfunction.
Methods and Results: A series of 158 patients with acute MI and left ventricular ejection fraction (LVEF) <50% were studied. Their age was 60 ± 10 years and LVEF 40 ± 6%. MCG was registered and FRA was computed. For comparison, QRS duration in 12-lead ECG was measured. In a mean follow-up of 50 ± 15 months, 32 (20%) patients died and 18 (11%) had an arrhythmic event. Both arrhythmic event rate and all-cause mortality were significantly higher in patients with increased FRA (P < 0.001 for both). In contrast, increased QRS duration in ECG predicted all-cause mortality (P < 0.05) but not arrhythmic events. In multivariate analysis, FRA was an independent predictor of both arrhythmic events and all-cause mortality. Using a combined criterion of increased FRA and LVEF < 30% yielded positive and negative predictive accuracies of 50% and 91% for arrhythmic events.
Conclusion: In post-MI patients with left ventricular dysfunction, increased intra-QRS fragmentation in high-resolution magnetocardiography predicts arrhythmic events, whereas QRS duration in 12-lead ECG predicts all-cause mortality. Analysis of intra-QRS fragmentation by MCG may assist in guiding therapy of post-MI patients, for example, by selecting those who would benefit most from prophylactic implantable cardioverter-defibrillator therapy.     

Eficácia das terapias de pacing auricular antitaquicardia no tratamento da fibrilhação auricular paroxística em doentes portadores de pacemaker

IntroductionThe aim of this study was to assess the effectiveness of atrial antitachycardia pacing (ATP) in the conversion of atrial tachyarrhythmia episodes, and its impact in reducing arrhythmic burden.MethodsWe performed a retrospective study in the pacing laboratory of a district hospital of 57 consecutive patients implanted with a dual chamber pacemaker, capable of performing atrial antitachycardia pacing, between 2005 and 2010. The patients were divided into two groups: ATP_ON (n=24) and ATP_OFF (n=33). The follow‐up period was 15 months, with data being collected at three follow‐up consultations: the first at three months after implantation, the second at nine months and the last at 15 months. In this period, there were 12 428 ATP therapies of atrial tachyarrhythmias.ResultsAlthough there were no statistically significant differences, there was a trend in favor of the ATP_ON group, the increase in arrhythmic burden being less marked in this group. The mean percentage of ventricular apical pacing was also significantly lower in this group, which was associated with a marginally significant reduction in arrhythmic burden (p=0.06). There was a significant positive correlation between changes in the percentage of ventricular pacing and changes in arrhythmic burden (r=0.417, p=0.02).ConclusionsAtrial antitachycardia pacing converted 59.7% of episodes of atrial arrhythmia, but did not significantly reduce arrhythmic burden. There was a significant positive correlation between changes in the percentage of ventricular pacing and changes in arrhythmic burden.     

Risk of cardiovascular,cardiac and arrhythmic complications in patients with non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease(NAFLD)has emerged as a public health problem of epidemic proportions worldwide.Accumulating clinical and epidemiological evidence indicates that NAFLD is not only associated with liver-related morbidity and mortality but also with an increased risk of coronary heart disease(CHD),abnormalities of cardiac function and structure(e.g.,left ventricular dysfunction and hypertrophy,and heart failure),valvular heart disease(e.g.,aortic valve sclerosis)and arrhythmias(e.g.,atrial fibrillation).Experimental evidence suggests that NAFLD itself,especially in its more severe forms,exacerbates systemic/hepatic insulin resistance,causes atherogenic dyslipidemia,and releases a variety of pro-inflammatory,pro-coagulant and pro-fibrogenic mediators that may play important roles in the pathophysiology of cardiac and arrhythmic complications.Collectively,these findings suggest that patients with NAFLD may benefit from more intensive surveillance and early treatment interventions to decrease the risk for CHD and other cardiac/arrhythmic complications.The purpose of this clinical review is to summarize the rapidly expanding body of evidence that supports a strong association between NAFLD and cardiovascular,cardiac and arrhythmic complications,to briefly examine the putative biological mechanisms underlying this association,and to discuss some of the current treatment options that may influence both NAFLD and its related cardiac and arrhythmic complications.     

Quabain-induced arrhythmias of single isolated myocardial cells and cell clusters cultured in vitro and their improvement by quinidine

Single isolated myocardial cells obtained in vitro from fetal mouse heart in medium containing ouabain developed various types of arrhythmic movements, such as fibrillatory and fluttering movements. The percentage of single isolated myocardial cells which exhibited arrhythmic movements increased with increase in ouabain concentration. The arrhythmic movements of single isolated myocardial cells induced by relatively low concentrations of ouabain were improved by addition of quinidine.Cell clusters also developed various types of arrhythmic movements in medium containing ouabain. These arrhythmias became more severe on increasing the ouabain concentration. Under conditions when approximately 43% of single isolated myocardial cells showed arrhythmic movements, many cells in cell clusters showed fibrillatory movements, but the cell clusters as a whole still maintained rhythmic beating. Under conditions when approximately 65% of single isolated myocardial cells showed arrhythmic movements, cell clusters as a whole showed irregular beating. The cell clusters stopped beating under conditions when about 79% of single isolated myocardial cells showed arrhythmic movements. Relatively mild types of arrhythmic movements of cell clusters were improved by addition of quinidine. From these observations, the genesis and improvement of arrhythmic movements of cell clusters were explained as essentially due to the genesis and improvement of arrhythmic movements of the individual component cells in the clusters.     

Effectiveness of implantable defibrillators for preventing arrhythmic events and death: a meta-analysis

OBJECTIVES: The aim of this study was to compare the effectiveness of the implantable cardioverter defibrillator (ICD) and medical strategies for prevention of arrhythmic events and death. BACKGROUND: The ICD is a potential strategy to reduce mortality in patients at risk of sudden death. METHODS: The MEDLINE, EMBASE, and Cochrane Library electronic databases were searched from January 1966 to April 2002. All published randomized controlled trials comparing ICD implantation with medical therapy were reviewed. Four independent reviewers extracted data on all-cause mortality, nonarrhythmic death, and arrhythmic death using a standardized protocol. RESULTS: Nine studies including over 5,000 patients were synthesized using both fixed-effects and random-effects models. The primary and secondary prevention trials showed a significant benefit of the ICD with respect to arrhythmic death, with relative risks (RR) of 0.34 and 0.50, respectively (both p < 0.001). The mortality benefit of the ICD was entirely attributable to a reduction in arrhythmic death (all trials: p < 0.00001). Whereas the secondary prevention trials exhibited a robust decrease in all-cause ICD mortality (RR 0.75; p < 0.001), the pooled primary prevention trials demonstrated decreased all-cause ICD mortality (RR 0.66; p < 0.05) which was dependent on selected individual trials. The disparity in ICD-related mortality reductions in the primary prevention trials was related to variability in the incidence of arrhythmic death between individual studies. CONCLUSIONS: Although the ICD decreases the risk of arrhythmic death, its impact on all-cause mortality is related to the underlying risk of arrhythmia-related death relative to competing causes. Given the cost of the device strategy, policies of targeted intervention based on the future risk of arrhythmia are warranted.     

Arrhythmic movements of myocardial cells in culture and their improvement with antiarrhythmic drugs

Various types of arrhythmic movements of single isolated myocardial cells and clusters of these cells were observed on incubation in medium containing ouabain, or of low potassium or high calcium concentration. The percentage of single isolated cells which exhibited arrhythmic movements increased with increase in ouabain concentration, or calcium concentration, or decrease in potassium concentration. Under conditions causing increase in the percentage of arrhythmic single cells, the arrhythmic movements of cell clusters became more severe. The arrhythmic movements of both single isolated cells and cell clusters were improved by addition of antiarrhythmic drugs, such as quinidine or procaine amide. The genesis and improvement of arrhythmic movements of cell clusters were explained as due in part to the genesis and improvement of arrhythmic movements of the component cells in the clusters.     

NAFLD,and cardiovascular and cardiac diseases: Factors influencing risk,prediction and treatment

Background and aimNon-alcoholic fatty liver disease (NAFLD), affecting up to around 30% of the world’s adult population, causes considerable liver-related and extrahepatic morbidity and mortality. Strong evidence indicates that NAFLD (especially its more severe forms) is associated with a greater risk of all-cause mortality, and the predominant cause of mortality in this patient population is cardiovascular disease (CVD). This narrative review aims to discuss the strong association between NAFLD and increased risk of cardiovascular, cardiac and arrhythmic complications. Also discussed are the putative mechanisms linking NAFLD to CVD and other cardiac/arrhythmic complications, with a brief summary of CVD risk prediction/stratification and management of the increased CVD risk observed in patients with NAFLD.ResultsNAFLD is associated with an increased risk of CVD events and other cardiac complications (left ventricular hypertrophy, valvular calcification, certain arrhythmias) independently of traditional CVD risk factors. The magnitude of risk of CVD and other cardiac/arrhythmic complications parallels the severity of NAFLD (especially liver fibrosis severity). There are most likely multiple underlying mechanisms through which NAFLD may increase risk of CVD and cardiac/arrhythmic complications. Indeed, NAFLD exacerbates hepatic and systemic insulin resistance, promotes atherogenic dyslipidaemia, induces hypertension, and triggers synthesis of proatherogenic, procoagulant and proinflammatory mediators that may contribute to the development of CVD and other cardiac/arrhythmic complications.ConclusionCareful assessment of CVD risk is mandatory in patients with NAFLD for primary prevention of CVD, together with pharmacological treatment for coexisting CVD risk factors.     

Arrhythmic risk stratification of post-myocardial infarction patients

Post-myocardial infarction risk stratification, especially arrhythmic risk stratification, is an issue that has still not been wholly addressed in modern clinical cardiology. In the past 10 years, arrhythmic risk stratification has been approached mainly by evaluating frequency and complexity of premature ventricular contractions, detected on Holter monitoring, often in association with determination of percent ejection fraction. This methodology has been proven to be limited and fallacious according to the Cardiac Arrhythmia Suppression Trial I and II (CAST I,II) results, in which suppression of premature ventricular contractions or premature ventricular beats throughout by antiarrhythmic drugs resulted in an increase in both cardiac and arrhythmic mortality. Only amiodarone as an antiarrhythmic drug, as proven in the recent European Myocardial Infarct Amiodarone Trial (EMIAT) and Canadian Amiodarone Myocardial Infarction Trial (CAMIAT), was effective in reducing arrhythmic mortality without affecting cardiac mortality, in patients selected mainly because of a reduced ejection fraction, with and without premature ventricular contractions. Conversely, it is well known that beta-blockers are effective in preventing sudden death in post-acute myocardial infarction (AMI) patients, thus reducing cardiac and arrhythmic mortality. Conversely, in other institutions, risk stratification in post-AMI patients has been performed by electrophysiologic study obtained, without any previous noninvasive arrhythmic risk stratification, in all post-AMI patients. In recent years, many other noninvasive electrocardiology parameters, such as late potentials (signal-averaged electrocardiography), heart rate variability, baroreflex sensitivity, and, more recently, T-wave alternance, have been shown to be useful, but they are associated with a low specificity in the noninvasive identification of patients at high risk for arrhythmic mortality. Conversely, in the Multicenter Automatic Defibrillation Implantation Trial (MADIT), electrophysiology confirmed that inducibility of ventricular tachycardia shows high specificity and a high predictive value for arrhythmic events. Nevertheless, the MADIT study population is not comparable to a cohort of consecutive patients who have recently had a myocardial infarction. In this setting, the highest risk of arrhythmic events can be observed in patients with depressed percent ejection fraction (< 35%) and in the first 6 months after AMI. Today, the most convincing approach seems to be the one combining both noninvasive risk stratification parameters (e.g., premature ventricular beats > 10/h or reduced heart rate variability < 70 ms or a positive signal-averaged electrocardiogram) followed by a further arrhythmic risk stratification, obtained through electrophysiologic study. Several published and ongoing trials that utilize various arrhythmic risk stratification techniques as part of their protocol are reviewed.     

Frequency of arrhythmic events during head-up tilt testing in patients with suspected neurocardiogenic syncope or presyncope

Head-up tilt testing (HUT) is a useful diagnostic tool for evaluating suspected neurocardiogenic syncope. Although arrhythmic events during HUT have been occasionally reported, their incidence in a large number of patients is unknown. We aimed to assess the incidence and clinical significance of arrhythmic events in patients with suspected neurocardiogenic syncope who underwent HUT with isoproterenol provocation. For 2,242 patients who underwent HUT, the incidence of total arrhythmic events was 31%: bradyarrhythmias 24%, premature beats 4%, and tachyarrhythmias 3%. For 547 patients who developed bradyarrhythmias during HUT, the incidence of junctional arrhythmias was 92%. For 702 arrhythmic events, the incidence of arrhythmic events during the first phase of HUT was significantly lower than the second phase (p <0.001). The incidence of arrhythmic events in patients with positive HUT responses was significantly higher than in those with negative responses (p <0.001). In patients with positive responses, bradyarrhythmias were noted in 85%, and junctional arrhythmia was the most common arrhythmic event. Of the positive responses, 353 patients (61%) had the vasodepressive type, 181 (32%) patients the mixed type, and the remaining 39 (7%) the cardioinhibitory type. Of 2,242 patients, ventricular fibrillation occurred in 1 patient (0.04%). Thus, bradyarrhythmias were the most common arrhythmic events during HUT with isoproterenol provocation. Serious ventricular tachyarrhythmia rarely occurred.     

Implantable cardioverter defibrillator therapy in athletes

Implantable cardioverter defibrillators (ICD) prevent recurrent arrhythmic death in sudden death survivors or may prevent its development in physically active patients with an underlying risk for malignant ventricular arrhythmias. Although ICD do not substitute for the usual recommendations to refrain from intensive or competitive exercise because of an underlying arrhythmic disorder, they often provide a means for safe continuation of mild to moderate recreational sports activity. Long-term quality of life will be highly dependent on the prevention of inappropriate ICD shocks. This requires the choice of a durable lead and device system, careful programming tailored to the characteristics of the patient's physiologic and pathologic heart rhythms, preventive bradycardic medication, and guided rehabilitation with psychologic counseling.     

Combined assessment of T-wave alternans and late potentials used to predict arrhythmic events after myocardial infarction. A prospective study

OBJECTIVES: The aim of the present study was to determine whether the combination of two markers that reflect depolarization and repolarization abnormalities can predict future arrhythmic events after acute myocardial infarction (MI). BACKGROUND: Although various noninvasive markers have been used to predict arrhythmic events after MI, the positive predictive value of the markers remains low. METHODS: We prospectively assessed T-wave alternans (TWA) and late potentials (LP) by signal-averaged electrocardiogram (ECG) and ejection fraction (EF) in 102 patients with successful determination results after acute MI. The TWA was analyzed using the power-spectral method during supine bicycle exercise testing. No antiarrhythmic drugs were used during the follow-up period. The study end point was the documentation of ventricular arrhythmias. RESULTS: The TWA was present in 50 patients (49%), LP present in 21 patients (21%), and an EF <40% in 28 patients (27%). During a follow-up period of 13 +/- 6 months, symptomatic, sustained ventricular tachycardia or ventricular fibrillation occurred in 15 patients (15%). The event rates were significantly higher in patients with TWA, LP, or an abnormal EF. The sensitivity and the negative predictive value of TWA in predicting arrhythmic events were very high (93% and 98%, respectively), whereas its positive predictive value (28%) was lower than those for LP and EF. The highest positive predictive value (50%) was obtained when TWA and LP were combined. CONCLUSIONS: The combined assessment of TWA and LP was associated with a high positive predictive value for an arrhythmic event after acute MI. Therefore, it could be a useful index to identify patients at high risk of arrhythmic events.     

Predictive value of T-wave alternans for arrhythmic events in patients with congestive heart failure

Measurement of microvolt level T-wave alternans in the surface electrocardiogram is a novel way to assess the risk of ventricular arrhythmias. Seven tests of arrhythmic risk, including T-wave alternans, were undertaken in 107 consecutive patients with congestive heart failure and no history of sustained ventricular arrhythmias; the patients were followed up for arrhythmic events during the next 18 months. Of the patients with events, 11 had positive and two indeterminate T-wave alternans results; there were no arrhythmic events among patients with negative T-wave alternans results. Of the seven tests, only T-wave alternans was a significant (p=0.0036) and independent predictor of arrhythmic events.     

Location of death (in-hospital or out-of-hospital) and type of death (arrhythmic, nonarrhythmic, noncardiac) after inducible sustained ventricular tachyarrhythmias after syncope, sustained ventricular tachycardia, or nonfatal cardiac arrest (the ESVEM trial)

The ESVEM Trial evaluated methods to guide antiarrhythmic drug use in patients with spontaneous, inducible sustained tachyarrhythmias at electrophysiologic testing and frequent ventricular premature complexes (VPCs) per hour (>/=10). We assessed the relation between location (in-hospital or out-of-hospital) and classification of death (arrhythmic, nonarrhythmic, cardiac and/or noncardiac) for 486 randomized patients. Deaths were classified as out-of-hospital arrhythmic deaths if arrhythmic death occurred out-of-hospital, or if an arrhythmia preceded hospital admission and directly caused death. Of the 486 randomized patients, 188 (39%) died during 6 years of follow-up. The location and type of death could be determined clearly in 171 patients (91%). Ninety-one deaths were in-hospital (53%); 80 were out-of-hospital (47%). Arrhythmic deaths occurred in 85% out-of-hospital patients and in 30% in-hospital patients (p <0.001). Baseline characteristics were comparable for patients with out-of-hospital and in-hospital arrhythmic deaths. Twenty-seven of 95 arrhythmic deaths occurred in-hospital (28%); 72% occurred out-of-hospital. Out-of-hospital arrhythmic death accounted for 40% of deaths for which location and type of information were available. The 1- and 4-year actuarial out-of-hospital arrhythmic death rates were 9% and 18%, respectively. Of nonarrhythmic cardiac deaths, 91% were in-hospital and 9% were out-of-hospital. Of noncardiac deaths, 74% were in-hospital and 26% were out-of-hospital. Similar results were seen in the 296 patients for whom a drug was considered to be effective. Thus, over half the deaths in the ESVEM trial occurred in-hospital. The long-term actuarial risk of out-of-hospital arrhythmic death in ESVEM was unexpectedly low.     

Spectral Turbulence Versus Time-Domain Analysis of Signal-Averaged ECG Used for the Prediction of Different Arrhythmic Events in Survivors of Acute Myocardial Infarction

Spectral Turbulence SAECG After MI. Introduction : Spectral turbulence analysis of the signal-averaged ECG (SAECG) combines spectral analysis with statistical evaluation of spectrograms of individual parts of the QRS complex. It has been suggested that it may be superior to conventional time-domain analysis of the SAECG.
Methods and Results : This study compared the power of conventional time-domain (40 to 250Hz) and spectral turbulence analyses of SAECG for the prediction of cardiac death, ventricular tachycardia, sudden arrhythmic death, and arrhythmic events (ventricular tachycardia or fibrillation, and/or sudden arrhythmic death) after acute myocardial infarction in 603 patients. The population excluded patients with bundle branch block and other conduction abnormalities. During the first 2 years of follow-up, there were 40 cardiac deaths, 21 cases of ventricular tachycardia, 11 sudden arrhythmic deaths, and 29 arrhythmic events. The positive predictive accuracy of spectral turbulence analysis was significantly higher than time-domain analysis for cardiac death at most levels of sensitivity (e.g., 26% vs 20% at 40% sensitivity, P < 0.05). The positive predictive accuracies of the two techniques were not statistically different for the prediction of ventricular tachycardia. For the prediction of sudden arrhythmic death and arrhythmic events, the positive predictive accuracy of spectral turbulence was better than that of time-domain analysis only at the higher levels of sensitivity (9% vs 2%, P < 0.001 for sudden arrhythmic death at 60% sensitivity, and 14% vs 11%, P < 0.05 for arrhythmic events at 60% sensitivity).
Conclusions : Spectral turbulence analysis is essentially equivalent to time-domain analysis for the prediction of arrhythmic events after myocardial infarction. However, it performed significantly better than time-domain analysis for the prediction of cardiac death.     

Effects of stress and exercise tests on the functional state of cardiac performance and the state of adrenergic regulation in patients with ischemic heart disease

In patients with coronary heart disease, stress was found to provoke both ischemic and arrhythmic responses. As compared with exercise test, stress caused arrhythmic reactions more frequently than ischemic ones. Stress was ascertained to provoke ischemic and arrhythmic reactions mainly via increased cardiac function. It also affected the myocardium and coronary bed by the direct action of catecholamines and other stress hormones.     

The Cardiac Arrhythmia Suppression Trial: background, interim results and implications

The Cardiac Arrhythmia Suppression Trial (CAST) was designed to test the hypothesis that suppression of ventricular premature complexes (VPCs) in survivors of acute myocardial infarction would reduce arrhythmic death risk. Instead, a preliminary finding from the CAST was that the encainide and flecainide groups had a 3.6-fold increase in arrhythmic death compared with their placebo group. These unfortunate results were especially surprising in that the CAST population represented patients in whom the risk of arrhythmic death was only moderate and the risk of proarrhythmia was thought to be low. In contrast, the arrhythmic death rate of the CAST placebo group was unusually low, to the extent that it paralleled the arrhythmic death rate in previous clinical trials of patients surviving myocardial infarction with no ventricular arrhythmia. The excessive arrhythmic death rate in patients taking encainide and flecainide occurred over the duration of the CAST, implying a proarrhythmic effect that may be due to mechanisms that are unique in this population, and thus challenging traditional concepts of proarrhythmia. The existing knowledge regarding the proarrhythmic and negative inotropic effects of encainide and flecainide are reviewed. The previous pharmaceutical database experience with these 2 antiarrhythmic drugs exceeded 3,000 patients; however, there was no indication of this serious proarrhythmic effect. In contrast, the CAST population taking encainide and flecainide totaled only 725 patients who were followed for 10 months and had an extremely high proarrhythmic event rate. The reasons for this discrepancy are discussed. The results of the CAST emphasize the power of a randomized, placebo-controlled clinical trial to uncover previously unsuspected benefits or liabilities of traditional therapies.     

Preventing Sudden Death after Repair of Tetralogy of Fallot:

Sudden arrhythmic death in patients with repaired tetralogy of Fallot or its variants has a variety of causes. Consequently, it can serve as a paradigm for management of potentially malignant arrhythmias in all pediatric patients, particularly with regard to the use of nonpharmacologic therapy for management. Five cases are presented as touchpoints for discussion and demonstrate a number of important issues concerning the assessment and reduction of sudden cardiac death risk in these patients. First, there are no clinical parameters that can be used to accurately assess risk. Second, pharmacologic agents alone rarely are adequate therapy. Third, catheter ablation and antitachycardia devices continue to play an ever increasing role in management of these patients, and, finally, additional data are necessary to establish clear management guidelines in patients with congenital heart disease at risk for arrhythmic death.     

Arrhythmic Events and Mortality in Patients With Cardiogenic Shock on Inotropic Support: Results of the DOREMI Randomized Trial

BackgroundInotropic support is widely used in the management of cardiogenic shock (CS). Existing data on the incidence and significance of arrhythmic events in patients with CS on inotropic support is at high risk of bias.MethodsThe Dobutamine Compared to Milrinone (DOREMI) trial randomized patients to receive dobutamine or milrinone in a double-blind fashion. Patients with and without arrhythmic events (defined as arrhythmias requiring intervention or sustained ventricular arrhythmias) were compared to identify factors associated with their occurrence, and to examine their association with in-hospital mortality and secondary outcomes.ResultsNinety-two patients (47.9%) had arrhythmic events, occurring equally with dobutamine and milrinone (P = 0.563). The need for vasopressor support at initiation of the inotrope and a history of atrial fibrillation were positively associated with arrhythmic events, whereas predominant right ventricular dysfunction, previous myocardial infarction, and increasing left ventricular ejection fraction were negatively associated with them. Supraventricular arrhythmic events were not associated with mortality (relative risk [RR], 0.97; 95% confidence interval [CI], 0.68-1.40; P = 0.879) but were positively associated with resuscitated cardiac arrests and hospital length of stay. Ventricular arrhythmic events were positively associated with mortality (RR, 1.66; 95% CI, 1.13-2.43; P = 0.026) and resuscitated cardiac arrests. Arrhythmic events were most often treated with amiodarone (97%) and electrical cardioversion (27%), which were not associated with mortality.ConclusionsClinically relevant arrhythmic events occur in approximately one-half of patients with CS treated with dobutamine or milrinone and are associated with adverse clinical outcomes. Five factors may help to identify patients most at risk of arrhythmic events.