One-year prognosis of primary ventricular fibrillation complicating acute myocardial infarction. The GISSI (Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto miocardico) investigators

In-hospital predictors for primary prevention of sudden death after acute myocardial infarction with cardiac dysfunction

BACKGROUND

Current guidelines recommend prophylactic defibrillator implantation in patients with acute myocardial infarction (AMI) and left ventricular ejection fraction (LVEF) ≤40 % or LVEF ≤35 % plus heart failure symptoms or inducible ventricular tachyarrhythmias during an electrophysiology study at 40 days after AMI or 90 days after revascularization. In-hospital predictors of sudden cardiac death (SCD) after AMI during the index hospitalization remain unsettled. We sought to examine in-hospital predictors of SCD in patients with AMI and LVEF ≤40 % evaluated during the index hospitalization.

METHODS

We retrospectively evaluated 441 consecutive patients with AMI and LVEF ≤40 % admitted to our hospital between 2001 and 2014 (77 % male gender; median age: 70 years; median hospitalization length: 23 days). The primary endpoint was a composite of SCD or aborted SCD at ≥30 days after AMI onset (composite arrhythmic event). LVEF and QRS duration (QRSd) on electrocardiography were measured at a median of 12 days and 18 days, respectively.

RESULTS

During a median follow-up of 7.6 years, the incidence of composite arrhythmic events was 7.3 % (32 of 441 patients). In multivariable analysis, QRSd ≥100 msec (beta-coefficient = 1.54, p = 0.003), LVEF ≤23 % (beta-coefficient = 1.14, p = 0.007), and onset-reperfusion time > 5.5 h (beta-coefficient = 1.16, p = 0.035) were independent predictors of composite arrhythmic events. The combination of these 3 factors was associated with the highest rate of composite arrhythmic events compared with 0-2 factors (p < 0.001).

CONCLUSIONS

The combination of QRSd ≥100 msec, LVEF ≤23 %, and onset-reperfusion time > 5.5 h during the index hospitalization provides precise risk stratification for SCD in patients early after AMI.

Early ICD implantation in cardiac arrest survivors with acute coronary syndrome - predictors of implantation, ICD-therapy and long-term survival

Objectives. Implantable cardioverter defibrillator (ICD) implantation in patients resuscitated from out-of-hospital cardiac arrest (OHCA) due to acute myocardial infarction (AMI) is controversial. Design. Consecutive OHCA-survivors due to AMI from two Danish tertiary heart centers from 2007 to 2011 were included. Predictors of ICD-implantation, ICD-therapy and long-term survival (5 years) were investigated. Patients with and without ICD-implantation during the index hospital admission were included (later described as early ICD-implantation). Patients with an ICD after hospital discharge were censored from further analyses at time of implantation. Results. We identified 1,457 consecutive OHCA-patients, and 292 (20%) of the cohort met the inclusion criteria. An ICD was implanted during hospital admission in 78 patients (27%). STEMI and successful revascularization were inversely and independently associated with ICD-implantation (OR_STEMI = 0.37, 95% CI: 0.14-0.94, OR_revasc = 0.11, 0.03-0.36) whereas age, sex, LVEF <35%, comorbidity burden or shockable first OHCA-rhythm were not associated with ICD-implantation. Appropriate ICD-shock therapy during the follow-up period was noted in 15% of patients (n = 12). Five-year mortality-rate was significantly lower in ICD-patients (18% vs. 28%, p_logrank = 0.02), which was persistent after adjustment for prognostic factors (HR = 0.44 (95% CI: 0.23-0.88)). This association was no longer found when using first event (death or appropriate shock whatever came first) as outcome variable (p_logrank = 0.9). Conclusions. Mortality after OHCA due to AMI was significantly lower in patients with early ICD-implantation after adjustment for prognostic factors. When using appropriate shock and death as events, ICD-patients had similar outcome as patients without an ICD, which may suggest a survival benefit due to appropriate device therapy.

Cardiac arrhythmias in the emergency settings of acute coronary syndrome and revascularization: an European Heart Rhythm Association (EHRA) consensus document, endorsed by the European Association of Percutaneous Cardiovascular Interventions (EAPCI), and European Acute Cardiovascular Care Association (ACCA)

Despite major therapeutic advances over the last decades, complex supraventricular and ventricular arrhythmias (VAs), particularly in the emergency setting or during revascularization for acute myocardial infarction (AMI), remain an important clinical problem. Although the incidence of VAs has declined in the hospital phase of acute coronary syndromes (ACS), mainly due to prompt revascularization and optimal medical therapy, still up to 6% patients with ACS develop ventricular tachycardia and/or ventricular fibrillation within the first hours of ACS symptoms. Despite sustained VAs being perceived predictors of worse in-hospital outcomes, specific associations between the type of VAs, arrhythmia timing, applied treatment strategies and long-term prognosis in AMI are vague. Atrial fibrillation (AF) is the most common supraventricular tachyarrhythmia that may be asymptomatic and/or may be associated with rapid haemodynamic deterioration requiring immediate treatment. It is estimated that over 20% AMI patients may have a history of AF, whereas the new-onset arrhythmia may occur in 5% patients with ST elevation myocardial infarction. Importantly, patients who were treated with primary percutaneous coronary intervention for AMI and developed AF have higher rates of adverse events and mortality compared with subjects free of arrhythmia. The scope of this position document is to cover the clinical implications and pharmacological/non-pharmacological management of arrhythmias in emergency presentations and during revascularization. Current evidence for clinical relevance of specific types of VAs complicating AMI in relation to arrhythmia timing has been discussed.

Ventricular Arrhythmias in Patients with Spontaneous Coronary Artery Dissection: Findings from the Gulf Spontaneous Coronary Artery Dissection (Gulf SCAD) Registry

BACKGROUND

Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of acute coronary syndrome in young women, with a wide clinical spectrum of severity. Ventricular arrhythmia (VA) can occur and worsen prognosis. The current study compared in-hospital and follow-up adverse cardiovascular events in patients with and without VA at presentation.

METHODS

Eighty-three cases of SCAD were collected retrospectively from 4 Gulf countries (KSA, UAE, Kuwait, and Bahrain) during the period from January 2011 to December 2017. We divided the patients into 2 groups: those with and without VA at presentation. VA was defined as ventricular tachycardia and/or ventricular fibrillation. In-hospital (recurrent VA, cardiogenic shock, death, implantable cardioverter-defibrillator placement, dissection extension) and follow-up (MI, de novo SCAD, death, spontaneous superior mesenteric artery dissection) events were compared among the 2 groups.

RESULTS

The median age of patients in the study was 44 (37-55) years. Forty-two (51%) were women. VA occurred in 10 (12%) patients in the first 24-hour of hospitalization, and 5 (50%) of those patients had recurrent in-hospital VA. Among those with recurrent VA, 1 died during hospitalization and 1 died within the first year following hospital discharge.

CONCLUSIONS

In-hospital adverse cardiovascular events were significantly more frequent for patients with SCAD who presented with VA. However, follow-up events were not statistically significant between those with and without VA at presentation.

ICD implantation for secondary prevention in patients with ventricular arrhythmia in the setting of acute cardiac ischemia and a history of myocardial infarction

INTRODUCTION

In patients with a prior myocardial infarction (MI) but preserved left ventricular (LV) function, sustained ventricular arrhythmias (VAs) may arise in the setting of an acute coronary syndrome (ACS). It is unknown whether an implantable cardioverter-defibrillator (ICD) is mandatory in these patients as VA might be triggered by a reversible cause. The purpose of this study is to analyze the benefit of ICD therapy in this patient population.

METHODS

We conducted a retrospective observational study in ICD recipients implanted from 2008 to 2011. The study group consisted of patients with sustained VA in the setting of an ACS, with a history of MI, but with left ventricular ejection fraction (LVEF) greater than 35 (group A). The two control groups consisted of patients admitted with VA with a history of MI, but without ACS at presentation, either with LVEF greater than 35% (group B) or ≤35% (group C). The primary endpoint was the number of patients with appropriate ICD therapy (antitachycardia pacing or shock).

RESULTS

A total of 291 patients were included with a mean follow-up of 5.3 years. Appropriate ICD therapy occurred in 45.6% of the patients in group A vs 51.6% and 60.4% in groups B and C (P = .11). In group A, 31.1% received an appropriate ICD shock vs 34.7% and 44.3% in control groups B and C (P = .12).

CONCLUSION

On the basis of these data, ICD implantation seems warranted in patients with history of MI presenting with VA in the setting of an ACS, despite preserved LV function and adequate revascularization. Further trials, preferably randomizes, should be performed to address these findings.

Primary Ventricular Fibrillation in the Primary Percutaneous Coronary Intervention ST-Segment Elevation Myocardial Infarction Era (from the "Codi IAM" Multicenter Registry)

Primary ventricular fibrillation (PVF) is a dreadful complication of ST segment elevation myocardial infarction (STEMI). Scarce data are available regarding PVF prognosis since primary percutaneous coronary intervention (PPCI) became routine practice in STEMI. Our aim was to compare 30-day and 1-year mortality for patients with and without PVF (including out-of-hospital and in-hospital PVF) within a regional registry of PPCI-treated STEMI patients. This prospective multicenter registry included all consecutive STEMI patients treated with PPCI from January 2010 to December 2014. Patients were classified as non-PVF or PVF, with further subdivision into out-of-hospital and in-hospital PVF. We analyzed 30-day and 1-year all-cause mortality in groups. The registry included 10,965 patients. PVF occurred in 949 patients (8.65%), including 74.2% out-of-hospital and 25.8% in-hospital PVF. Compared with the non-PVF group, PVF patients were younger; less commonly diabetic; more frequently had anterior wall STEMI, higher Killip-Kimball class, and left main disease; and showed significantly higher 24-hour (5.1% vs 1.1%), 30-day (18.5% vs 4.7%), and 1-year mortality (23.2% vs 7.9%) (all p <0.001). Mortality did not differ in out-of-hospital versus in-hospital PVF. After multivariable adjustment, PVF remained associated with all-cause 30-day (2.32, 95% CI: 1.91 to 2.82, p <0.001) and 1-year (HR: 1.59, 95% CI: 1.13 to 2.24, p = 0.008) mortality. In conclusion, we present the largest registry of PVF patients in the era of routine PPCI in STEMI. Although overall STEMI mortality has declined, PVF emerged as a predictor of both 30-day and 1-year mortality. These data warrant prospective validation and proper identification and protection of high-risk patients.

Impact of out-of-hospital cardiac arrest due to ventricular fibrillation in patients with ST-elevation myocardial infarction admitted for primary percutaneous coronary intervention: Impact of ventricular fibrillation in STEMI patients

OBJECTIVE

Pre-hospital life-threatening ventricular tachycardia/fibrillation (VT/VF) is relatively common in the acute phase of ST-elevation myocardial infarction (STEMI). We evaluated the prognostic impact of out-of-hospital cardiac arrest (OHCA) due to VT/VF in non-selected patients with STEMI admitted for primary percutaneous coronary intervention (PCI).

METHODS

Prospective hospital registry was used to collect data of consecutive STEMI patients admitted to our hospital between 2005 and 2010. Patients with OHCA were identified from this registry, and their medical records were reviewed.

RESULTS

During the study period, 4653 patients were admitted with STEMI. Data regarding OHCA due to VT/VF was available in 4643 patients (99.8%). A total of 326 patients (7.0%) had OHCA due to VT/VF. Patients with OHCA were younger (60.3 ± 11.8 vs. 64.1 ± 12.9 year, p<0.001), less often had diabetes (5.2% vs. 12.4%, p<0.001) but more often presented with signs of heart failure (Killip class >1:17.5% vs. 7.7%, p<0.001) and cardiogenic shock (29.6% vs. 2.5%, p<0.001). Coronary angiography was performed in 97.5% of the patients. Coronary angiography and primary PCI were performed equally in both groups. In patients with OHCA, the left main artery (2.3% vs. 1.0%, p=0.04) and LAD (49.2% vs. 41.2%, p=0.01) were more often the culprit artery. In-hospital mortality was significantly higher among patients with OHCA (13.80% vs. 3.4%, p<0.001). However, in patients who were discharged alive from the hospital, the one-year mortality and the combined incidence of death and appropriate ICD therapy were similar in patients with and without OHCA.

CONCLUSION

In a large non-selected STEMI patient population admitted for primary PCI, OHCA due to VT/VF was associated with higher in-hospital mortality but did not affect the long-term prognosis.

Prognostic impact of early ventricular fibrillation in patients with ST-elevation myocardial infarction treated with primary PCI

AIMS

Current guidelines do not advocate implantation of cardioverter-defibrillators (ICD) for survivors of ventricular fibrillation (VF) during the first 48 hours of ST-elevation myocardial infarction (STEMI). However, contemporary studies in a real-life setting with long-term follow-up are lacking. We assessed the prognostic impact of early VF in a non-selected population of STEMI patients treated with primary percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Consecutive STEMI patients admitted to a Swedish tertiary care hospital during 2007-2009 were identified from the Register of Information and Knowledge about Swedish Heart Intensive Care Admissions (n=1718, age 66±12 years, 70% male). Patients with VF were identified from the register, and medical records were reviewed to determine the time point of VF. Patients surviving VF in the first 48 hours after symptom onset were compared with patients without VF for one-year mortality and a combined endpoint of death, resuscitated VF or appropriate ICD therapy. VF within 48 hours occurred in 7% of STEMI patients (n=121). In patients alive at 48 hours (n=1663), VF patients (n=101) had higher in-hospital mortality (12% vs. 2%, p<0.001). However, in VF patients discharged alive (n=89), mortality was low (1%) and combined endpoint rate (3%) did not differ compared with patients without VF (n=1538; 4% and 4% respectively).

CONCLUSION

In a large non-selected population of STEMI patients treated with primary PCI, VF during the first 48 hours after STEMI is associated with increased in-hospital mortality but does not influence the long-term prognosis for those discharged alive.

Occurrence, characteristics, and outcome of patients hospitalized with a diagnosis of acute myocardial infarction who do not fulfill traditional criteria

BACKGROUND

The diagnosis of acute myocardial infarction (AMI) is traditionally based on clinical history, elevation of serum enzyme activity, and typical changes in the electrocardiogram (ECG); however, not all patients who develop AMI fulfill these criteria on discharge from hospital.

HYPOTHESIS

The aim of the study was to evaluate (1) the frequency with which the traditional criteria for AMI are not fulfilled among patients diagnosed with AMI on discharge, and (2) whether patients with and without these criteria differ in terms of characteristics, treatment, and outcome.

METHODS

All patients aged < 75 years and hospitalized in the municipality of Göteborg with a discharge diagnosis of AMI were included. Fulfillment criteria for AMI were two of the following three points: (1) chest pain, (2) increase in cardiac enzymes, and (3) development of Q waves.

RESULTS

In all, 1,188 admitted patients, 27% of whom were women, were included in the analysis. Of these, 193 (16%) did not fulfill the traditional criteria for AMI. These patients had an in-hospital mortality rate of 48%; of these, 59% died a sudden death, and of those who were autopsied (62%), 96% showed signs of a fresh AMI. The most common symptom on admission to hospital in patients who did not fulfill the traditional criteria was chest pain (34%), followed by dyspnea (27%) and fatigue (14%). Of those who died suddenly, fewer than half had been admitted to the coronary care unit.

CONCLUSION

Patients diagnosed with AMI who do not fulfill the traditional diagnosis criteria have high mortality. On admission to hospital, the initial suspicion of AMI is often vague. Measures for earlier detection of life-threatening coronary artery disease among these patients are warranted.

Ventricular arrhythmias after acute myocardial infarction: a 20-year community study

BACKGROUND

Although myocardial infarction (MI) severity is declining, the occurrence of ventricular arrhythmia (VA) after MI and its effect on outcome is unknown. This study was undertaken to examine the frequency and timing of VA and the effect of VA on mortality after MI.

METHODS

Myocardial infarctions recorded between 1979 and 1998 were validated. Baseline characteristics, occurrence of VA, and survival were determined. Ventricular arrhythmias were categorized as primary ventricular fibrillation (VF), nonprimary VF, and ventricular tachycardia (VT). Logistic regression was used to analyze associations between VA and baseline characteristics. Temporal trends were assessed with the Mantel-Haenszel chi2. Survival was analyzed with the Kaplan-Meier method. Proportional hazards regression was used to examine the association between death and occurrence of VA.

RESULTS

Among 2317 persons with incident MI, 7.5% experienced VA (3.6% nonprimary VF, 2.1% primary VF, 1.8% VT). Ventricular arrhythmia-associated factors were younger age, female sex, higher Killip class, ST elevation, and atrial fibrillation. Ventricular arrhythmias were associated with increased risk of death at 30 days.

CONCLUSION

Ventricular arrhythmias after MI are relatively common, particularly among persons with more severe MI and no prior history of coronary disease. Over time, the incidence of VF declined, whereas VT did not change. Ventricular arrhythmia after MI was associated with a 6-fold increase in morality. Thus, identification of high-risk MI survivors and prevention of VA could markedly improve outcomes. Further studies are needed to determine the cause of the shift in distribution of VA subtype.

Arrhythmic complications of acute coronary syndromes

Cardiac arrhythmias routinely manifest during or following an acute coronary syndrome (ACS). Although the incidence of arrhythmia is directly related to the type of ACS the patient is experiencing, the clinician needs to be cautious with all patients in these categories. As an example, nearly 90% of patients who experience acute myocardial infarction (AMI) develop some cardiac rhythm abnormality and 25% have a cardiac conduction disturbance within 24 hours of infarct onset. In this patient population, the incidence of serious arrhythmias, such as ventricular fibrillation (4.5%) ,is greatest in the first hour of an AMI and declines rapidly thereafter. This article addresses the identification and treatment of arrhythmias and conduction disturbances that complicate the course of patients who have ACS, particularly AMI and thrombolysis. Emphasis is placed on mechanisms and therapeutic strategies.

Outcomes after ventricular fibrillation out-of-hospital cardiac arrest: expanding the chain of survival

Coronary heart disease is the most common cause of death in the United States, with ventricular fibrillation (VF) the most common initial rhythm when cardiac disease causes arrest. Survival after VF out-of-hospital cardiac arrest (OHCA) depends on a sequence of events called the chain of survival, which Includes rapid access to emergency medical services, cardiopulmonary resuscitation, defibrillation, and advanced care. Because of widespread implementation of defibrillation programs, more patients survive VF OHCAs, making subsequent care of these patients important. Early hospitalization must focus on potential neurologic injury and therapy targeted at the underlying cardiac disease and antiarrhythmic therapy for long-term secondary prevention of sudden death. Attention to certain cohorts who are at high risk despite their underlying disease, such as women and elderly patients, is necessary. These cohorts may have the greatest response to short-term and long-term therapies for cardiac rehabilitation. With these approaches, long-term survival and quality of life after VF OHCA are favorable. Broadening the focus of the chain of survival to include in-hospital and long-term care will further improve favorable outcomes achieved in an early defibrillation program.

Use of implantable cardioverter defibrillators after out-of-hospital cardiac arrest: a prospective follow-up study

BACKGROUND

Survivors of out-of-hospital cardiac arrest are at high risk of recurrent arrests, many of which could be prevented with implantable cardioverter defibrillators (ICDs). We sought to determine the ICD insertion rate among survivors of out-of-hospital cardiac arrest and to determine factors associated with ICD implantation.

METHODS

The Ontario Prehospital Advanced Life Support (OPALS) study is a prospective, multiphase, before-after study assessing the effectiveness of prehospital interventions for people experiencing cardiac arrest, trauma or respiratory arrest in 19 Ontario communities. We linked OPALS data describing survivors of cardiac arrest with data from all defibrillator implantation centres in Ontario.

RESULTS

From January 1997 to April 2002, 454 patients in the OPALS study survived to hospital discharge after experiencing an out-of-hospital cardiac arrest. The mean age was 65 (standard deviation 14) years, 122 (26.9%) were women, 398 (87.7%) had a witnessed arrest, 372 (81.9%) had an initial rhythm of ventricular tachycardia or ventricular fibrillation (VT/VF), and 76 (16.7%) had asystole or another arrhythmia. The median cerebral performance category at discharge (range 1-5, 1 = normal) was 1. Only 58 (12.8%) of the 454 patients received an ICD. Patients with an initial rhythm of VT/VF were more likely than those with an initial rhythm of asystole or another rhythm to undergo device insertion (adjusted odds ratio [OR] 9.63, 95% confidence interval [CI] 1.31-71.50). Similarly, patients with a normal cerebral performance score were more likely than those with abnormal scores to undergo ICD insertion (adjusted OR 12.52, 95% CI 1.74-92.12).

INTERPRETATION

A minority of patients who survived cardiac arrest underwent ICD insertion. It is unclear whether this low usage rate reflects referral bias, selection bias by electrophysiologists, supply constraint or patient preference.

Outcomes and in-hospital treatment of out-of-hospital cardiac arrest patients resuscitated from ventricular fibrillation by early defibrillation

OBJECTIVE

To describe and evaluate the in-hospital treatment of ventricular arrhythmias and underlying structural heart disease in patients who survive ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA) in a region with a high survival rate after hospital discharge.

PATIENTS AND METHODS

The study included all patients presenting in Olmsted County, Minnesota, who had experienced OHCA between November 1990 and December 2000 and who underwent defibrillation of VF by an emergency medical service system.

RESULTS

Of 200 patients who experienced VF arrest, 138 (69%) survived to hospital admission (7 died in the emergency department before admission), and 79 (40%) were discharged. Of patients who were discharged, 37 (47%) had a reversible cause of the arrest (perimyocardial infarction) and received treatment of the primary process. The other 42 patients who were discharged had ischemic coronary heart disease (CHD) (n=25), nonischemic CHD (n=10), or idiopathic VF (n=7). Four of the patients with CHD but no left ventricular dysfunction were treated with coronary artery bypass grafting or percutaneous coronary intervention alone. A total of 52 patients (66%) were candidates for electrophysiologic testing. Of these patients, 48 (92%) underwent electrophysiologic testing; of these patients, 10 received amiodarone alone, and 35 received an implantable cardioverter-defibrillator (ICD) (of whom 3 also received amiodarone). Patients who did not receive ICD therapy typically presented before 1998 with CHD and underwent coronary artery bypass grafting or percutaneous coronary intervention only. Of 79 patients who were discharged, 14 (18%) with an ICD have received subsequent shocks. Nineteen (24%) of 79 patients have died, 5 of a primary cardiac etiology (including 2 with repeated OHCA).

CONCLUSIONS

The VF OHCA survival rate is high in the setting of rapid defibrillation, with 40% of patients being discharged from the hospital. By the end of the 10-year study, more patients were receiving antiarrhythmic therapy, in particular ICD implantation, after hospital admission. Overall, the long-term survival in patients with VF OHCA is favorable.

Cardiac troponin T and cardiac enzymes after external transthoracic cardioversion of ventricular arrhythmias in patients with coronary artery disease

BACKGROUND

Serum levels of cardiac troponins after external cardioversion (ECV) for atrial fibrillation and atrial flutter are widely investigated, and no increases in cardiac troponin T (cTnT) levels have been reported. However, the effect of ECV on cardiac enzyme release may depend on the type of arrhythmias. Furthermore, ventricular tachycardia (VT) or ventricular fibrillation (VF) could cause release of cardiac enzymes after ECV due to underlying myocardial ischemia, myocardial dysfunction, or more pronounced hemodynamic deterioration during arrhythmia.

AIM

The purpose of this study was to determine whether direct current (DC) shock may increase cardiac enzyme levels in patients with coronary artery disease undergoing ECV for VT or VF, so that diagnosis of acute myocardial infarction, which initially presents with VT or VF, can be excluded.

METHOD AND RESULTS

We obtained measurement of cTnT, total creatine kinase (CK), and CK MB isoenzyme (CK-MB) activity before and after ECV in 27 patients (mean +/- SD age, 62 +/- 13 years) with induced VT or VF (22 patients) who required ECV during provocative electrophysiologic testing and who underwent ECV due to VT (5 patients) in the cardiology department. Blood samples were drawn before, and 4 h, 8 h, and 24 h after ECV. The total energy used was 630 +/- 375 J (range, 200 to 1,280 J). CK levels rose to the upper limit of reference range in seven patients (26%), and CK-MB activity was higher than the normal reference range in five patients (19%) after ECV. In contrast, cTnT concentrations remained within the normal range (< 0.1 micro g/L) in all patients. Peak CK and CK-MB activity levels strongly correlated with the total energy delivered.

CONCLUSION

Elevation of cTnT level after an urgent DC shock strongly indicates the diagnosis of acute myocardial infarction presented with life-threatening arrhythmias, rather than myocardial damage caused by ECV.

Ischemia, metabolic disturbances, and arrhythmogenesis: mechanisms and management

The development of ventricular arrhythmias is often a consequence of the interaction between structural abnormalities of the heart and transient disturbances in the electrophysiologic milieu. The critically ill patient is particularly susceptible to arrhythmias given the metabolic, ischemic, and neurohormonal stressors present in the intensive care unit. The significance of ventricular arrhythmias in the acute care setting is related to the presence of reversible causes and the extent of underlying heart disease. Long-term management of these patients is guided by an assessment of the risk for recurrent arrhythmias and the degree of left ventricular systolic dysfunction. In the absence of a reversible cause, symptomatic sustained arrhythmias are usually treated with an implantable cardioverter-defibrillator, a therapy that improves survival in this patient population. In many cases, however, proper long-term management of patients with ventricular arrhythmias is less clear, and the approach must be guided by a thorough understanding of the pathophysiology and the fundamental mechanisms of arrhythmogenesis.

Is hospital care of major importance for outcome after out-of-hospital cardiac arrest? Experience acquired from patients with out-of-hospital cardiac arrest resuscitated by the same Emergency Medical Service and admitted to one of two hospitals over a 16-year period in the municipality of Göteborg

AIM

To describe patient characteristics, hospital investigations and interventions and early mortality among patients being hospitalized after out-of-hospital cardiac arrest in two hospitals.

SETTING

Municipality of Göteborg, Sweden.

PATIENTS

All patients suffering an out-of-hospital cardiac arrest who were successfully resuscitated and admitted to hospital between 1 October 1980 and 31 December 1996. All patients were resuscitated by the same Emergency Medical Service and admitted alive to one of the two city hospitals in Göteborg.

RESULTS

Of 579 patients admitted to Sahlgrenska Hospital, 253 (44%) were discharged alive and of 459 patients admitted to Ostra Hospital, 152 (33%) were discharged alive (P < 0.001). More patients in Sahlgrenska Hospital were still receiving cardiopulmonary resuscitation (CPR) treatment (P = 0.03), but patients in Ostra had a lower systolic blood pressure and higher heart rate on admission. A larger percentage of patients admitted to Sahlgrenska Hospital underwent coronary angiography (P < 0.001), electrophysiological testing (P < 0.001), Holter recording (P < 0.001), echocardiography (P = 0.004), percutaneous transluminal coronary angioplasty (PTCA, P = 0.009), implantation of automatic implantable cardioverter defibrillator (AICD, P = 0.03) and exercise stress tests (P = 0.003). Inhabitants in the catchment area of Ostra Hospital had a less favourable socio-economic profile.

CONCLUSION

Survival after out-of-hospital cardiac arrest may be affected by the course of hospital management. Other variables that might influence survival are socio-economic factors and cardiorespiratory status on admission to hospital. Further investigation is called for as more patients are being hospitalised alive after out-of-hospital cardiac arrest.

Implantable defibrillators and antiarrhythmic drugs in patients at risk for lethal arrhythmias

The high mortality rate and frequency of ventricular arrhythmias in patients with congestive heart failure has prompted numerous clinical trials aimed at reducing mortality by addressing arrhythmic death. Recently completed trials have suggested that for patients who have survived cardiac arrest, the preferred treatment may be an implantable cardioverter defibrillator (ICD). From the standpoint of primary prevention, implantable defibrillators and amiodarone have received the most attention. It remains unclear, however, to which patients these studies apply, and if and how the results might be generalized. No available studies confirm an additional benefit of pharmacologic or device-based antiarrhythmic therapy beyond that offered by optimal treatment with beta blockers, angiotensin-converting enzyme inhibitors, and lipid-lowering drugs in the majority of patients with cardiomyopathy. Clinical trials are ongoing to address these issues.

Sustained ventricular arrhythmias in patients receiving thrombolytic therapy: incidence and outcomes. The GUSTO Investigators

BACKGROUND

Sustained ventricular tachycardia (VT) and fibrillation (VF) occur in up to 20% of patients with acute myocardial infarction (MI) and have been associated with a poor prognosis. The relationships among the type of arrhythmia (VT versus VF or both), time of VT/VF occurrence, use of thrombolytic agents, and eventual outcome are unclear.

METHODS AND RESULTS

In the GUSTO-I study, we examined variables associated with the occurrence of VT/VF and its impact on mortality. Of the 40 895 patients with ventricular arrhythmia data, 4188 (10.2%) had sustained VT, VF, or both. Older age, systemic hypertension, previous MI, Killip class, anterior infarct, and depressed ejection fraction were associated with a higher risk of sustained VT and VF (P<0.001). In-hospital and 30-day mortality rates were higher among patients with sustained VT/VF than among patients without sustained ventricular arrhythmias (P<0.001). Both early (<2 days) and late (>2 days) occurrences of sustained VT and VF were associated with a higher risk of later mortality (P<0. 001). In addition, patients with both VT and VF had worse outcomes than those with either VT or VF alone (P<0.001). Among patients who survived hospitalization, no significant difference was found in 30-day mortality between the VT/VF and no VT/VF groups. However, after 1 year, the mortality rate was significantly higher in the VT alone and VT/VF groups (P<0.0001).

CONCLUSIONS

Despite the use of thrombolytic therapy, both early and late occurrences of sustained VT or VF continue to have a negative impact on patient outcome; patients with both VT and VF had the worst outcome; and among patients who survived hospitalization, the 1-year mortality rate was significantly higher in those who experienced VT alone or VT and VF.

Nonsustained ventricular tachycardia in the setting of acute myocardial infarction: tachycardia characteristics and their prognostic implications

BACKGROUND

Nonsustained ventricular tachycardia (NSVT) has significant prognostic implications in the setting of healing and healed myocardial infarction (MI), but only limited information is available on its importance in the setting of acute MI. We evaluated the prognostic significance of NSVT characteristics in the setting of acute MI.

METHODS AND RESULTS

A prospective database was used to identify 112 patients with NSVT within 72 hours of acute MI. A control group was identified matched for age, sex, type of MI, and thrombolytic treatment. Mean age was 64 to 65 years in the 2 groups with 71% to 72% men. Q-wave MI was noted in 52% to 53%, and thrombolytic therapy was administered to 31% to 32% of patients in each group. In-hospital ventricular fibrillation occurred more frequently in the NSVT group (9% versus 0% in the control group; P<0. 001), but total in-hospital (10% versus 4%) and follow-up mortality (10% versus 17%) did not differ between the 2 groups. With a Cox regression model, specific NSVT characteristics were predictive of mortality. The strongest predictor was time from presentation to occurrence of NSVT. Shortest RR interval during NSVT was also a univariate predictor of mortality. Multivariate analysis identified time from presentation to occurrence of NSVT as the strongest predictor of mortality (P<0.0001). The increased relative risk of NSVT was first significant when it occurred 13 hours from presentation and continued to increase as the time from presentation to occurrence of NSVT increased, plateauing at approximately 24 hours with a relative risk of 7.5.

CONCLUSIONS

Contrary to prevailing clinical opinion, NSVT that occurs in the setting of acute MI does have important prognostic significance. Specifically, the currently accepted notion that NSVT that occurs within 48 hours of acute MI has no prognostic significance needs to be adjusted. Although NSVT that occurs within the first several hours of presentation does not have an associated adverse prognosis, NSVT that occurs beyond the first several hours after presentation is associated with significant increases in relative risk.

Incidence and prognosis of early primary ventricular fibrillation in acute myocardial infarction--results of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI-2) database

Primary ventricular fibrillation (VF) complicating acute myocardial infarction (MI) predicts short-term mortality. The broad category of patients with primary VF might include subgroups with different outcomes. It is still not certain whether early-onset (< or =4 hours) primary VF is a risk predictor, and information on correlates of these early fibrillations is scarce. This study sought to prospectively analyze the incidence and prognosis of early, as opposed to late (time window >4 to 48 hours) primary VF and retrospectively identify predisposing factors for early-onset primary VF. We analyzed the incidence and recurrence rate of early and late primary VF in 9,720 patients with a first acute MI, treated with thrombolytics, enrolled in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI)-2 trial. The independent prognostic significance of early and late primary VF was assessed by logistic regression analysis. The incidence rates of early and late primary VF were 3.1% and 0.6%, respectively; recurrence rates were 11% and 15%, respectively. The 2 variables most closely related to early primary VF were hypokalemia and systolic blood pressure < 120 mm Hg on admission. Patients with early primary VF had a more complicated in-hospital course than matched controls. Both early (odds ratio [OR] 2.47, 95% confidence interval [CI] 1.48 to 4.13) and late primary VF (OR 3.97, 95% CI 1.51 to 10.48) were independent predictors of in-hospital mortality. Postdischarge to 6-month death rates were similar for both primary VF subgroups and controls. Primary VF, irrespective of its timing, was an independent predictor of in-hospital mortality. Postdischarge to 6-month prognosis was unaffected by the occurrence of either early or late primary VF.

Arrhythmias associated with acute myocardial infarction and thrombolysis

Ninety percent of patients with acute myocardial infarction have some cardiac rhythm abnormality, and approximately twenty-five percent have cardiac conduction disturbance within 24 hours following infarct onset. Almost any rhythm disturbance can be associated with acute myocardial infarction, including bradyarrhythmias, supraventricular tachyarrhythmias, ventricular arrhythmias, and atrioventricular block. With the advent of thrombolytic therapy, it was found that some rhythm disturbances in patients with acute myocardial infarction may be related to successful coronary artery reperfusion. This article addresses the role and treatment of arrhythmias and conduction disturbances that complicate the course of patients with acute infarction and thrombolysis.

Effect of DC shock on serum levels of total creatine kinase, MB-creatine kinase mass and troponin T

After successful resuscitation from cardiac arrest, it is important to identify whether the event has been triggered by a myocardial infarction, since this determines subsequent investigations and management. Previous studies have shown that biochemical indices of infarction become elevated after resuscitation in patients without myocardial infarction. This can lead to overdiagnosis of myocardial infarction in the post-arrest setting. The cause of the elevated enzyme levels is not known, but may involve electrical or mechanical injury to the heart during resuscitation. In this study we aimed to identify the effects of isolated direct current shock on serum levels of creatine kinase (CK), MB creatine kinase mass (MB-CK), and troponin T, and examined the relationships between enzyme levels and the dose of electrical energy used. Thirteen patients were studied who underwent DC cardioversion for atrial fibrillation. Serum was obtained for CK, MB-CK and troponin T estimation before and 10 min after cardioversion, at hourly intervals for 8 h, and 18 h after cardioversion. Total serum CK became significantly elevated after only 3 h and rose to a peak of 1294.4 IU l(-1) (P < 0.02) at 18 h. Post-shock CK levels were strongly correlated with total shock energy (r = 0.8, P < 0.01). Serum MB-CK was significantly elevated at 18 h among patients receiving total shock energies greater than 1000 J than in those receiving lower doses, reflecting a positive correlation (r = 0.64, P < 0.05) between shock energy and peak MB-CK level. Troponin T levels were not significantly elevated after cardioversion. In conclusion, total serum CK levels become significantly elevated early after cardioversion, suggesting rapid wash-out from injured skeletal muscle. MB-CK levels become significantly elevated in individuals receiving high energy shocks, probably due to release of small quantities of the CK-MB isoform from skeletal muscle. The negligible troponin T levels seen after high energy cardioversion indicate that significant myocardial injury does not occur. Electrical injury is not likely to account for the elevated troponin T levels seen after out-of-hospital resuscitation in patients without myocardial infarction.

General principles of antiarrhythmic therapy for ventricular tachyarrhythmias

Sudden cardiac death due to ventricular arrhythmias is a significant cause of mortality in patients with structural heart disease. Over the past several decades, the introduction of new pharmacologic and nonpharmacologic therapy has expanded the treatment options available. This article will focus on the use of antiarrhythmic medication for the treatment of ventricular arrhythmias and will review the following: (1) treatment goals for various clinical populations, (2) the mechanisms of antiarrhythmic and proarrhythmic actions of antiarrhythmic medications, and (3) empiric versus guided pharmacologic therapy.

Resuscitation from out-of-hospital cardiac arrest: implications for cardiac enzyme estimation

BACKGROUND

diagnosis of precipitating myocardial infarction is essential for management of victims of out-of-hospital cardiac arrest, since investigations and treatment are determined by the underlying cause. Skeletal muscle and myocardial damage from external cardiac massage and defibrillation may complicate biochemical diagnosis of myocardial infarction.

OBJECTIVES

(a) to examine the relationship between cumulative defibrillation energy and serum levels of cardiac troponin T and MB creatine kinase (MB-CK) mass in out-of-hospital cardiac arrest survivors without electrocardiographic evidence of myocardial infarction; (b) to reassess diagnostic thresholds for myocardial infarction using MB-CK mass and troponin T in this setting.

METHODS

77 victims of out-of-hospital cardiac arrest were studied. Serum was obtained for MB-CK mass, CK and troponin T estimation on the first 4 days of admission. Patients were divided into three groups using electrocardiographic criteria: group 1, myocardial infarction; group 2, no evidence of infarction; and group 3, equivocal electrocardiograms. Correlation coefficients were calculated for highest recorded levels of the biochemical markers versus defibrillation energy. Receiver-operating characteristic plots were used to determine optimum biochemical diagnostic thresholds for subjects in groups 1 and 2.

RESULTS

using predefined criteria, 27 patients had myocardial infarction, 34 did not have myocardial infarction and 16 had equivocal electrocardiograms. Significant correlations were found for defibrillation energy versus log troponin T (r = 0.42, P < 0.05), log MB-CK mass (r = 0.51, P < 0.01) and total CK (r = 0.68, P < 0.001) in group 2. Within groups 1 and 2, MB-CK mass and troponin T provided additional diagnostic value over MB-CK fraction (P < 0.001). Diagnostic accuracy was not improved by adjusting for shock energy. The optimum threshold value was 4 ng/ml for troponin T (sensitivity 88%, specificity 95%), 60 ng/ml for MB-CK mass (sensitivity 88%, specificity 88%) and 8% of total CK for MB-CK fraction (sensitivity 74%, specificity 82%). These values should be interpreted with caution, since this study is limited by the exclusion of patients with uncertain electrocardiographic diagnoses into group 3.

CONCLUSIONS

skeletal muscle and myocardial damage occurs in survivors of out-of-hospital cardiac arrest and is related to the duration of resuscitation. This complicates biochemical diagnosis of underlying myocardial infarction. Specific high diagnostic threshold values for MB-CK and troponin T are needed to optimise diagnostic accuracy. The use of MB-CK fraction leads to greater diagnostic error because of the variability of muscle CK release after resuscitation.

Methodologic sources of inconsistent prognoses for post-acute myocardial infarction

PURPOSE

To investigate basic methodologic problems that could explain inconsistent and contradictory results for predictor variables in studies of prognosis after myocardial infarction (MI).

MATERIALS AND METHODS

Studies on postinfarct prognosis published in English between 1979 and 1991 were identified with a MEDLINE literature search. The key words used for the computer search were: "prognosis" and "myocardial infarction" in the title and "mortality" or "survival" or "outcome" in the title or abstract. Reference lists in the reports captured by the search were examined for pertinent articles, and additional articles were sought in the index pages of two prominent journals. To be included in the analysis, a study had to fulfill the following eligibility criteria: a cohort study or randomized, controlled trial; sample size > or = 50 patients; a clear identification of the time when follow-up began, after the acute phase of MI and either before or at hospital discharge; follow-up for a minimum of 6 months or median/mean of 1 year; and multivariable analysis for intervals no longer than 2 years after the MI. Eight methodologic standards addressing sources of major problems were established and applied to each study.

RESULTS

Of 766 reports identified, 111 fulfilled the eligibility criteria. The median number of standards fulfilled was 3, the highest 6. The proportions of studies complying with each of the 8 methodologic standards were: (1) inception cohort, 60%; (2) total death as an unequivocal outcome, 54%; (3) verification of cause-specific deaths (in 62 studies analyzing cardiac death), 37%; (4) analysis of crucial variables describing baseline severity, 13%; (5) indication of quantitative scope of the spectrum of baseline severity, 20%; (6) reproducible classification of candidate predictor variables, 40%; (7) adequate identification of quantitative importance of and boundaries for statistically significant predictor variables, 39%; and (8) evaluation of impact of treatment on predictor variables, 13%.

CONCLUSIONS

The results show that studies on postinfarct prognosis have frequently disregarded basic methodologic principles. Suitable adherence to these principles in future research will allow improved interpretation of results and can reduce inconsistent findings, while improving the applicability of the identified predictors.

Lidocaine prophylaxis for fatal ventricular arrhythmias after acute myocardial infarction

OBJECTIVE

To compare the efficacy and safety of a 40-hour lidocaine infusion after completion of a 8-hour open-label infusion for prophylaxis of primary ventricular fibrillation in patients with uncomplicated acute myocardial infarction.

METHODS

This was a double-blind, randomized placebo-controlled trial held in the coronary care unit of a large nonprofit hospital. We studied 200 patients with uncomplicated acute myocardial infarction in Killip class I or II who came to the hospital within 6 hours of onset of symptoms and 22 patients who had ventricular fibrillation before the start of the study. Intervention consisted of an 8-hour lidocaine infusion followed by placebo or lidocaine for an additional 40 hours. The infusion rate was adjusted in patients > or = 70 years old and in those < 50 kg or > or = 90 kg. Measurements recorded were baseline demographic characteristics, incidence of ventricular arrhythmias, adverse reactions, and death.

RESULTS

New congestive heart failure developed during the randomized phase in 9% of patients receiving lidocaine and in 2% of patients receiving placebo (p = 0.03). Ventricular fibrillation did not occur during the treatment period, and sustained ventricular tachycardia developed in one patient receiving placebo. The in-hospital mortality rate was comparable in both groups (4% versus 2%; p = 0.68) but was much higher (13.6%) in patients with initial ventricular fibrillation not included in the randomized study.

CONCLUSIONS

A 40-hour age- and weight-adjusted lidocaine infusion administered after an initial 8-hour infusion provoked more congestive heart failure than placebo. In view of the absence of ventricular fibrillation episodes with both infusions, caution should be used when lidocaine is administered for longer than 8 hours in patients with uncomplicated myocardial infarction.

Prognosis of early versus late ventricular fibrillation complicating acute myocardial infarction

Earlier studies have suggested that patients exhibiting late (> 24 h) ventricular fibrillation during acute myocardial infarction had a poorer outcome in comparison to myocardial infarction patients with early (< 24 h) ventricular fibrillation. Between August 1981 and July 1983, 5839 consecutive patients with acute myocardial infarction were hospitalized in 13 out of 21 operating coronary care units in Israel. Demographic and medical data were collected from hospitalization charts and during 1 year of follow-up. Mortality assessment was done for 99% of hospital survivors up to mid-1988 (mean, 5.5 years). The incidence of ventricular fibrillation in the SPRINT Registry was 6% (371/5839). Patients with ventricular fibrillation in the setting of cardiogenic shock (n = 107) were excluded from analysis. Patients with late ventricular fibrillation (n = 109; 41%) were older and had a more complicated hospital course than patients with early ventricular fibrillation (n = 155; 59%). In-hospital and 1-year post-discharge mortality were significantly higher in patients with late ventricular fibrillation (63% and 17%) as compared to patients with early ventricular fibrillation (26% and 4%, respectively; P < 0.05 for each). This difference vanished 5 years after hospital discharge. After multiple logistic regression analysis late occurrence of ventricular fibrillation emerged as an independent predictor of increased in-hospital mortality (Odds ratio, 4.29; 95% confidence interval, 2.11-8.74) but not for subsequent death. Patients with late ventricular fibrillation during the hospital course of acute myocardial infarction had a poorer immediate and subsequent outcome in comparison to patients with early ventricular fibrillation.

Ventricular arrhythmias in trials of thrombolytic therapy for acute myocardial infarction. A meta-analysis

BACKGROUND

Although thrombolytic therapy reduces long-term mortality in acute myocardial infarction, many clinicians remain concerned about an increased risk of ventricular arrhythmias associated with the use of these agents.

METHODS AND RESULTS

To determine whether thrombolytic therapy increases the risk of ventricular tachyarrhythmias and whether an increase in arrhythmias could be responsible for the increased mortality seen in the first 24 hours after lytic therapy, we performed a meta-analysis of 15 randomized trials of thrombolysis in acute myocardial infarction in which the odds of developing in-hospital ventricular fibrillation (VF) and ventricular tachycardia (VT) in patients receiving thrombolysis was compared with that of patients receiving placebo. For trials that reported the incidence of VF during the first 6 hours after thrombolysis, the summary odds ratio for developing VF in the thrombolytic group was 0.98 (95% confidence interval [CI], 0.6 to 1.6; P = .94). For trials that reported the incidence of VF during the first hospital day, the summary odds ratio for developing VF was 1.00 (95% CI, 0.85 to 1.2; P = .95). The summary odds ratio for the development of VF at any time during hospitalization in the thrombolytic group was 0.83 (95% CI, 0.76 to 0.90; P < .0001). In trials that reported the incidence of VT any time during hospitalization, the summary odds ratio for the development of VT in the thrombolytic group was 1.34 (95% CI, 1.15 to 1.55; P < .0001).

CONCLUSIONS

The likelihood of developing VF in the early hours after thrombolysis for acute myocardial infarction is similar in patients receiving thrombolytics or placebo. However, throughout the hospital course, the risk of VF is greater in patients receiving placebo, whereas the risk of VT is higher in patients receiving thrombolysis.

Incidence and significance of ventricular tachycardia and fibrillation in the absence of hypotension or heart failure in acute myocardial infarction treated with recombinant tissue-type plasminogen activator: results from the Thrombolysis in Myocardial Infarction (TIMI) Phase II trial

OBJECTIVES

The purpose of this study was to determine the incidence of ventricular tachycardia and fibrillation without hypotension or heart failure after treatment with recombinant tissue-type plasminogen activator (rt-PA), anatomic correlates of their development, the effect of immediate intravenous metoprolol on their occurrence and the outcome of patients with these arrhythmias.

BACKGROUND

Malignant arrhythmias after thrombolytic therapy have been reported to occur as a result of coronary reperfusion, which is associated with reduced mortality in patients receiving thrombolytic therapy.

METHODS

We analyzed data from 2,546 patients in the Thrombolysis in Myocardial Infarction (TIMI) Phase II trial without congestive heart failure or hypotension during the 1st 24 h after study entry. Forty-nine patients (1.9%) developed sustained ventricular tachycardia or ventricular fibrillation within 24 h of study entry (group 1), and 2,497 patients (98.1%) did not (group 2).

RESULTS

Baseline characteristics and admission laboratory values were similar in the two groups. In patients undergoing protocol angiography 18 to 48 h after rt-PA, the infarct-related artery was patient in a greater percent of group 2 patients (87% [1,015 of 1,169]) than group 1 patients (68% [15 of 22], p = 0.01), although angiography was performed less frequently in group 1 than in group 2. More group 1 than group 2 patients died within 21 days (20.4%) (1.6%, p < 0.001). For patients surviving to 21 days, there was no difference in mortality between patients in the two groups in the following year.

CONCLUSIONS

Ventricular tachycardia and fibrillation are not markers for reperfusion after thrombolytic therapy. These arrhythmias are associated with occlusion, not patency, of the infarct-related artery. Early mortality is increased in patients who develop ventricular tachycardia and fibrillation, even in the absence of congestive heart failure and hypotension.

Early out-of-hospital lidocaine administration decreases the incidence of primary ventricular fibrillation in acute myocardial infarction

This study was designed to assess the effectiveness of early prehospital intravenous administration of lidocaine in preventing primary ventricular fibrillation (PVF) in patients with suspected acute myocardial infarction (AMI). Sixty patients with suspected AMI, seen by the Mobile Coronary Care Unit (MCCU) of Florence, were randomly allocated at home to treatment with lidocaine (bolus i.v. of 1 mg/kg, followed by an infusion of 4 mg/min) or placebo (infusion of saline at a rate of 1 mL/min), respectively. The lidocaine group (27 patients) and the control group (33 patients) were not significantly different in age, clinical condition, or time of randomization. The diagnosis of AMI was confirmed in all 60 patients during the hospital stay. Ventricular fibrillation (VF) occurred in 5 patients in the control group in comparison to none in the lidocaine group (P < 0.05). Three patients experienced VF at home and were successfully resuscitated by an MCCU cardiologist. In another two patients, VF occurred during the first 4 hours after onset of symptoms. No major side effects were observed after the infusion of lidocaine. Our findings support the effectiveness of the prophylactic administration of lidocaine in preventing PVF in the prehospital phase of AMI and suggest that the drug can be safely administered in this setting by prehospital personnel.

Frequency and prognostic significance of secondary ventricular fibrillation complicating acute myocardial infarction. SPRINT Study Group

The incidence of secondary ventricular fibrillation (VF) complicating acute myocardial infarction (AMI) was 2.4% in a large cohort of unselected patients with AMI (142 of 5,839). Secondary VF was more frequent in patients with recurrent AMI (4%) than in those with a first AMI (1.9%) (p < 0.01). The hospital course was more complicated and in-hospital mortality was significantly higher in patients with secondary VF than in those with the same clinical hemodynamic condition but without VF (56 vs 16%; p < 0.0001). Multivariate analyses confirmed secondary VF complicating AMI as an independent predictor of high in-hospital mortality, with an odds ratio of 7 (95% confidence interval 4.6-10.6). However, long-term mortality after discharge (mean follow-up 5.5 years) was not increased in patients with as compared with those without secondary VF (39 vs 42%). These findings were also true when patients receiving beta blockers and antiarrhythmic therapy were excluded from analysis. Thus, this life-threatening arrhythmia occurring during hospitalization is not a marker of recurrent susceptibility to VF or an indicator of increased mortality after discharge from the hospital.