Prognosis of acute myocardial infarction complicated by primary ventricular fibrillation. Principal Investigators of the SPRINT Study

Prognosis of the non-ST elevation myocardial infarction complicated with early ventricular fibrillation at higher age

Early ventricular fibrillation (EVF) predicts mortality in ST-segment elevation myocardial infarction (STEMI) patients. Data are lacking about prognosis and management of non-ST-segment elevation myocardial infarction (NSTEMI) EMI with EVF, especially at higher age. In the daily clinical practice, there is no clear prognosis of patients surviving EVF. The present study aimed to investigate the risk factors and factors influencing the prognosis of NSTEMI patients surviving EVF, especially at higher age. Clinical data, including 30-day and 1-year mortality of 6179 NSTEMI patients, were examined; 2.44% (n=151) survived EVF and were further analyzed using chi-square test and uni- and multivariate analyses. Patients were divided into two age groups below and above the age of 70 years. Survival time was compared with Kaplan-Meier analysis. EVF was an independent risk factor for mortality in NSTEMI patients below (HR: 2.4) and above the age of 70 (HR: 2.1). Mortality rates between the two age groups of NSTEMI patients with EVF did not differ significantly: 30-day mortality was 24% vs 40% (p=0.2709) and 1-year mortality was 39% vs 55% (p=0.2085). Additional mortality after 30 days to 1 year was 15% vs 14.6% (p=0.9728). Clinical characteristics of patients with EVF differed significantly from those without in both age groups. EVF after revascularization—within 48 h—had 11.2 OR for 30-day mortality above the age of 70. EVF in NSTEMI was an independent risk factor for mortality in both age groups. Invasive management and revascularization of NSTEMI patients with EVF is highly recommended. Closer follow-up and selection of patients (independent of age) for ICD implantation in the critical first month is essential.

Prognosis and clinical characteristics of patients with early ventricular fibrillation in the 6-week guideline-offered time period: is it safe to wait 6 weeks with the assessment? (results from the VMAJOR-MI Registry)

Background

The most common, potentially fatal complication following an acute myocardial infarction (AMI) is early ventricular fibrillation (EVF). According to the guidelines, the assessment of implanting an implantable cardioverter defibrillator (ICD) is sufficient 6 weeks after the event, in patients with reduced left ventricular ejection fraction (LVEF), regardless of VF. The present study aimed to evaluate the 6-week prognosis of patients surviving an EVF. We divided the patients in two group based on their general condition at the time they left the hospital. We investigated the clinical characteristics of patients discharged in good general health but still dying within 6 weeks.

Methods

The present study comprised 12,270 patients with AMI following their primary revascularization in the first 12 h of symptom onset. Five hundred and forty-seven of them suffered EVF due to the AMI. Clinical and 6-week mortality data were examined.

Results

Poor general condition correlates with multiple comorbidities, higher troponin levels, more severe complications after the event. Patients leaving in good condition thought to be low risk, from dying. But low LVEF, high blood sugar, high cardiac biomarker level, poor renal function elevates the risk of dying within 6 weeks. However, there is no difference in clinical characteristics between EVF- cases and EVF+ cases in good condition who dies within 6 weeks.

Conclusions

According to our study we can select patients who are safe in the critical 6-week period and those who need closer follow-up despite leaving in good general condition.

Pharmacologic inhibition of the mitochondrial Na+/Ca2+ exchanger protects against ventricular arrhythmias in a porcine model of ischemia-reperfusion

BACKGROUND

The mitochondrial Na+/Ca2+ exchanger (mNCX) has been implicated in the pathogenesis of arrhythmogenicity and myocardial reperfusion injury, rendering its inhibition a potential therapeutic strategy. We examined the effects of CGP-37157, a selective mNCX inhibitor, on arrhythmogenesis, infarct size (IS), and no reflow area (NRA) in a porcine model of ischemia-reperfusion.

METHODS

Forty pigs underwent myocardial ischemia for 60 minutes, followed by 2 hours of reperfusion. Animals were randomized to receive intracoronary infusion of 0.02 mg/kg CGP-37157 or vehicle, either before ischemia (n=17) or before reperfusion (n=17). Animals were monitored for arrhythmias. Myocardial area at risk (AR), IS, and NRA were measured by histopathology.

RESULTS

AR, NRA, and IS were comparable between groups. Administration of CGP-37157 before ischemia resulted in the following: (a) suppression of ventricular tachyarrhythmias (events/pig: 1.5±1.1 vs 3.5±1.9, p=0.014), (b) easier cardioversion of ventricular tachyarrhythmias (defibrillations required for cardioversion of each episode: 2.6±2.3 vs 6.2±2.1, p=0.006), and (c) decreased maximal depression of the J point (0.75±0.27 mm vs 1.75±0.82 mm, p=0.007), compared to controls. Administration of CGP-37157 before reperfusion expedited ST-segment resolution; complete ST-segment resolution within 30 minutes of reperfusion was observed in 7/8 CGP-37157-treated animals versus 1/9 controls (p=0.003).

CONCLUSIONS

In a porcine model of myocardial infarction, intracoronary administration of CGP-37157 did not decrease IS or NRA. However, it suppressed ventricular arrhythmias, decreased depression of the J point during ischemia and expedited ST-segment resolution after reperfusion. These findings motivate further investigation of pharmacologic mNCX inhibition as a potential therapeutic strategy to suppress arrhythmias in the injured heart.

Lower In-Hospital Ventricular Tachyarrhythmia in Patients With Acute Myocardial Infarction Receiving Prior Statin Therapy

We evaluated whether prior statin therapy reduces in-hospital ventricular tachycardia/ventricular fibrillation (VT/VF) in percutaneous coronary intervention (PCI) patients with acute myocardial infarction (MI). Among the 1177 patients from the Acute Myocardial Infarction Registry-National Institutes of Health (KAMIR-NIH), 823 (70%) patients received prior statin therapy. Prior statin therapy was associated with a reduced risk of VT/VF events in both adjusted propensity score analysis (odds ratio [OR] 0.414, 95% confidence interval [CI], 0.198-0.865, P = .019) and adjusted inverse probability of treatment weight analysis (OR 0.463, 95% CI, 0.216-0.994, P = .048). The risk of in-hospital death did not differ significantly between those with or without prior statin therapy (hazard ratio [HR] 0.416, 95% CI, 0.112-1.548, P = .191). Major adverse cardiac events occurred in 116 (8.9%) patients during follow-up. Prior statin therapy was associated with a lower risk of major adverse cardiac events during the follow-up period (HR 0.486, 95% CI, 0.243-0.974, P = .042); however, this was mainly driven by reduced noncardiac death. Prior statin therapy might reduce the incidence of serious cardiac tachyarrhythmia, such as VT/VF, in patients with MI undergoing PCI. However, the reduction in VT/VF due to prior statin therapy did not improve short- and long-term clinical outcomes.

Impact of electrical defibrillation on infarct size and no-reflow in pigs subjected to myocardial ischemia-reperfusion without and with ischemic conditioning

Ventricular fibrillation (VF) occurs frequently during myocardial ischemia-reperfusion (I/R) and must then be terminated by electrical defibrillation. We have investigated the impact of VF/defibrillation on infarct size (IS) or area of no reflow (NR) without and with ischemic conditioning interventions. Anesthetized pigs were subjected to 60/180 min of coronary occlusion/reperfusion. VF, as identified from the ECG, was terminated by intrathoracic defibrillation. The area at risk (AAR), IS, and NR were determined by staining techniques (patent blue, triphenyltetrazolium chloride, and thioflavin-S). Four experimental protocols were analyzed: I/R (n = 49), I/R with ischemic preconditioning (IPC; n = 22), I/R with ischemic postconditioning (POCO; n = 22), or I/R with remote IPC (RIPC; n = 34). The incidence of VF was not different between I/R (44%), IPC (45%), POCO (50%), and RIPC (33%). IS was reduced by IPC (23 ± 12% of AAR), POCO (31 ± 16%), and RIPC (22 ± 13%, all P < 0.05 vs. I/R: 41 ± 12%). NR was not different between protocols (I/R: 17 ± 15% of AAR, IPC: 15 ± 18%, POCO: 25 ± 16%, and RIPC: 18 ± 17%). In pigs with defibrillation, IS was 50% larger than in pigs without defibrillation but independent of the number of defibrillations. Analysis of covariance confirmed the established determinants of IS, i.e., AAR, residual blood flow during ischemia (RMBFi), and a conditioning protocol, and revealed VF/defibrillation as a novel covariate. VF/defibrillation in turn was associated with larger AAR and lower RMBFi. Lack of dose-response relation between IS and the number of defibrillations excluded direct electrical injury as the cause of increased IS. Obviously, AAR size and RMBFi account for both IS and the incidence of VF. IS and NR are mechanistically distinct phenomena.NEW & NOTEWORTHY Ventricular fibrillation/defibrillation is associated with increased infarct size. Electrical injury is unlikely the cause of such association, since there is no dose-response relation between infarct size and number of defibrillations. Ventricular fibrillation, in turn, is associated with a larger area at risk and lower residual blood flow.

Predictors of ventricular fibrillation at reperfusion in patients with acute ST-elevation myocardial infarction treated by primary percutaneous coronary intervention

Ventricular fibrillation (VF) during reperfusion (rVF) in ST-segment elevation myocardial infarction (STEMI) is an infrequent but serious event that complicates coronary interventions. The aim of this study was to analyze clinical predictors of rVF in an unselected population of patients with STEMI treated with percutaneous coronary intervention (PCI). Consecutive patients with STEMI admitted to a tertiary care hospital for primary PCI from 2007 to 2012 were retrospectively assessed for the presence of rVF. Admission electrocardiograms, stored in a digital format, were analyzed for a maximal ST-segment elevation in a single lead and the sum of ST-segment deviations in all leads. Clinical, electrocardiographic, and angiographic characteristics were tested for associations with rVF using logistic regression analysis. Among 3,724 patients with STEMI admitted from 2007 to 2012, 71 (1.9%) had rVF. In univariate analysis, history of myocardial infarction, aspirin and β-blocker use, VF before PCI, left main coronary artery disease, inferior myocardial infarction localization, symptom-to-balloon time <360 minutes, maximal ST-segment elevation in a single lead >300 μV, and sum of ST-segment deviations in all leads >1,500 μV were associated with increased risk for rVF. In a multivariate analysis, sum of ST-segment deviations in all leads >1500 μV (odds ratio 3.7, 95% confidence interval 1.45 to 9.41, p = 0.006) before PCI remained an independent predictor of rVF. In-hospital mortality was 18.3% in the rVF group and 3.3% in the group without VF (p <0.001), but rVF was not an independent predictor of in-hospital death. In conclusion, the magnitude of ST-segment elevation before PCI for STEMI independently predicts rVF and should be considered in periprocedural arrhythmic risk assessment. Despite higher in-hospital mortality in patients with rVF, rVF itself has no independent prognostic value for prognosis.

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.

Mechanisms of arrhythmias and conduction disorders in older adults

Aging is associated with an increased prevalence of cardiac arrhythmias, which contribute to higher morbidity and mortality in the elderly. The frequency of cardiac arrhythmias, particularly atrial fibrillation and ventricular tachyarrhythmia, is projected to increase as the population ages, greatly impacting health care resource utilization. Several clinical factors associated with the risk of arrhythmias have been identified in the population, yet the molecular bases for the increased predisposition to arrhythmogenesis in the elderly are not fully understood. This review highlights the epidemiology of cardiac dysrhythmias, changes in cardiac structure and function associated with aging, and the basis for arrhythmogenesis in the elderly.

Predictors of six-month major adverse cardiac events in 30-day survivors after acute myocardial infarction (from the Korea Acute Myocardial Infarction Registry)

Little is known about risk factors for 6-month major adverse cardiac events (MACEs) in 30-day survivors after acute myocardial infarction (AMI). We investigated predictors of 6-month MACE in 30-day survivors after MI from the Korea Acute Myocardial Infarction Registry (KAMIR). From November 2005 to January 2008, 9,706 patients (6,983 men, mean age 64.0 +/- 12.4 years) who survived >30 days after AMI were analyzed. The primary end point was 6-month MACEs including death, MI, and revascularization. During 6-month follow-up, 317 patients (3.2%) had MACEs including 66 (0.6%) deaths, 23 (0.2%) recurrent MIs, and 218 (2.2%) revascularizations. In multivariate logistic regression analysis, factors reflecting demographics (body mass index), severity of left ventricular systolic dysfunction (Killip class >I, in-hospital cardiogenic shock, use of intra-aortic balloon pump), residual myocardial ischemia (previous coronary heart disease, multivessel disease), and electrical instability (ventricular tachycardia/ventricular fibrillation on admission) were independent predictors of 6-month MACEs after adjustment for clinical, angiographic, and procedural data. Plasma level of N-terminal pro-B-type natriuretic peptide provided an additional prognostic value predicting 6-month MACEs. In conclusion, this study provides useful prognostic information for clinicians to advise patients who have survived the acute phase of MI. More intensive management is needed in survivors after MI with these high-risk features.

Thirty-year trends (1975-2005) in the magnitude, patient characteristics, and hospital outcomes of patients with acute myocardial infarction complicated by ventricular fibrillation

Limited contemporary data are available describing the incidence rates, hospital prognosis, and factors associated with the occurrence of ventricular fibrillation (VF) in patients hospitalized with acute myocardial infarction (AMI). The objectives of our study were to examine 3-decade-long trends (1975 to 2005) in the magnitude, predictors, and hospital case-fatality rates associated with VF in residents of a large New England metropolitan area hospitalized at all area medical centers with an uncomplicated AMI. The study population consisted of 7,472 residents of the Worcester (Massachusetts) metropolitan area hospitalized with an uncomplicated AMI in 15 annual periods from 1975 to 2005. The overall proportion of patients who developed VF was 4.2%. The incidence rates of VF remained stable from 1975 to 1995 but decreased thereafter, reaching their lowest frequency in 2005 (1.9%). Hospital case-fatality rates were significantly higher in patients with (40.9%) compared with those without (2.5%) VF. Decreases in hospital death rates over time were observed in patients with and without VF, with the decreases in death rates being greater for patients with VF. Patients who developed a Q-wave MI or a left or right bundle branch block were at particularly increased risk for developing VF. In conclusion, our results indicate that the incidence and hospital death rates associated with VF have decreased during recent years.

Early sustained ventricular arrhythmias complicating acute myocardial infarction

OBJECTIVE

Sustained ventricular arrhythmias complicate 2% to 20% of acute myocardial infarctions (MIs) and are associated with increased in-hospital mortality. However, it remains unclear whether successful mechanical revascularization improves outcomes in these patients. The objective of this analysis was to identify predictors of sustained ventricular arrhythmias after acute MI and to determine the influence of successful revascularization on in-hospital mortality.

METHODS

We conducted a retrospective cohort study of all patients who underwent percutaneous coronary intervention for acute MI in New York State between 1997 and 1999.

RESULTS

Of the 9015 patients who underwent percutaneous coronary intervention for acute MI, 472 (5.2%) developed sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) before revascularization. After multivariable adjustment, independent predictors of sustained VT/VF included cardiogenic shock (odds ratio [OR], 4.10; 95% confidence interval [CI], 3.20-5.58; P <.001), heart failure (OR, 2.86; 95% CI, 2.24-3.67: P <.001), chronic kidney disease (OR, 2.58; 95% CI, 1.27-5.23; P=.009), and presentation within 6 hours of symptom onset (OR, 1.46; 95% CI, 1.18-1.81; P=.001). Patients with sustained VT/VF had greater in-hospital mortality (16.3% vs 3.7%, P <.001). Although successful percutaneous coronary intervention was associated with decreased in-hospital mortality in patients with VT/VF (P <.001), patients with sustained VT/VF and successful revascularization experienced increased mortality compared with patients without sustained ventricular arrhythmias (P <.001).

CONCLUSION

Among patients undergoing percutaneous coronary intervention for acute MI, sustained VT/VF remains a significant complication associated with a 4-fold increased risk of in-hospital mortality. Early mortality is reduced after successful percutaneous coronary intervention, but remains elevated in this high-risk group.

Predictors of cardiac arrest occurring in the context of acute myocardial infarction

BACKGROUND

Cardiac arrest (CA) concurrent with acute myocardial infarction (AMI) claims the life of many patients with coronary artery disease (CAD). In this study, we investigated the predictors of CA during AMI.

METHOD

Patients admitted with CA concurrent with AMI (n = 31) were matched by age, gender, race, and left ventricular ejection fraction (LVEF) to patients with AMI but no CA (n = 70). All patients underwent coronary angiography. Binary logistic regression was used to identify independent predictors of CA during AMI.

RESULTS

A total of 101 patients (age = 61 +/- 13 years, men 76%, Caucasians 98%, LVEF 33 +/- 12%) admitted to the University of Pittsburgh Medical Center with AMI were included in this analysis. Patients with CA concurrent with the AMI were more likely to have proximal rather than distal coronary artery culprit lesions (odds ratio (OR) = 7.2, P = 0.019). Other predictors of CA in the context of AMI included negative family history of CAD (OR = 8.0, P = 0.026) and absence of sinus rhythm upon hospital admission (OR = 5.1, P = 0.030).

CONCLUSION

Proximity of culprit coronary lesion and presence of rhythm other than sinus rhythm at hospital admission are two strong predictors of CA in the context of AMI. The implication is that the mechanism of CA is primarily that of a large area of myocardial ischemia leading to lethal ventricular arrhythmia. Other predispositions such as genetic make-up cannot be ruled out.

Could sustained monomorphic ventricular tachycardia in the early phase of a prime acute myocardial infarction affect patient outcome?

OBJECTIVES

Sustained monomorphic ventricular tachycardia (SMVT) in the course of a prime acute myocardial infarction is not a common arrhythmia and its prognostic significance has not been specifically elucidated. The aim of the study was to estimate the prognostic implications of the occurrence of sustained monomorphic ventricular tachycardia in the early phase (<72 h) of a prime acute myocardial infarction.

METHODS

We studied 690 consecutive patients admitted to the coronary care unit with a diagnosis of a prime myocardial infarction. SMVT was observed in 18 (2.6%) patients and we followed these patients for establishing the prognostic value of the arrhythmia according to the clinical characteristics.

RESULTS

Patients with SMVT had a more extensive myocardial infarction based on the peak of the CK-MB isoenzyme activity (480+/-290 IU/L, vs 270+/-190 IU/L, P < .01), and higher mortality rate (40% vs 9%, P < .001). The independent predictors of SMVT were CK-MB (odds ratio [OR] 12.4), presence of complex ventricular arrhythmias (OR = 5.7), a wide QRS complex > or =130 milliseconds (OR = 4.8) and Killip class (OR = 4.8). The SMVT was itself an independent predictor of mortality (OR = 5.0). Compared with patients with ventricular fibrillation or polymorphic ventricular tachycardia, those with SMVT had a higher CK-MB activity, higher rate of wide QRS > or =130 milliseconds (33% vs 8%, P < .002), had a worse hemodynamic condition (Killip class >I:58% vs 23%, P < .04) and higher recurrence rate of ischemic events (68% vs 16%, P < .05). During the one year follow-up period, 4 patients (36.3%) of the 11 survivors from those with SMVT died of cardiac related causes.

CONCLUSIONS

SMVT during the first 72 h of a prime myocardial infarction is an index of a larger healing myocardium with acute very complexed electrophysiological changes and it is an independent predictor of in-hospital mortality and a prognostic factor of a poor one year outcome.

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.

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.

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.

Effect of thrombolytic therapy on QT dispersion in elderly versus younger patients with acute myocardial infarction

The objective of this study was to assess the degree of QT dispersion and effect of thrombolytic therapy on QT dispersion in elderly (age > or =65 years) versus younger (age <65 years) patients with acute myocardial infarction. The QT dispersion was measured manually in 10 +/- 2 leads of 12-lead electrocardiograms on admission, at completion of thrombolytic therapy, and at day 2 after thrombolytic therapy in 36 elderly (73 +/- 5.7 years) and 36 younger (59.9 +/- 7.7 years) patients with acute myocardial infarction. Before initiation of thrombolytic therapy, elderly patients had higher absolute and corrected QT dispersion than younger patients (absolute QT dispersion: 76.3 +/- 7.3 versus 69.6 +/- 7.5 milliseconds, respectively, P < 0.0001; corrected QT dispersion: 77.9 +/- 7.6 versus 70.8 +/- 7.4 milliseconds, respectively, P < 0.001). The difference in QT dispersion between elderly and younger patients persisted at the completion of thrombolytic therapy (absolute QT dispersion: 75.1 +/- 7.2 versus 69.1 +/- 8.4 milliseconds, respectively, P = 0.001; corrected QT dispersion: 77.2 +/- 7.2 versus 70.7 +/- 8.0 milliseconds, respectively, P = 0.001) and at day 2 after thrombolytic therapy (absolute QT dispersion: 74.1 +/- 8.2 versus 69 +/- 9.1 milliseconds, respectively, P = 0.01; corrected QT dispersion: 76.0 +/- 7.9 versus 70.5 +/- 8.8 milliseconds, respectively, P = 0.006). Compared with the prethrombolytic values, there was no significant change in absolute and corrected QT dispersion at the completion of thrombolytic therapy or at day 2 after thrombolytic therapy in elderly or younger patients. Elderly patients with acute myocardial infarction have higher QT dispersion than younger patients with acute myocardial infarction, and QT dispersion does not change early after thrombolytic therapy in elderly or younger patients.

Interaction between arrival time and thrombolytic treatment in determining early outcome of acute myocardial infarction

BACKGROUND

Shortening prehospital delay has been identified as an important means of improving responses to reperfusion treatment. If this increases the risk profile of the population delivered to hospital, it may paradoxically cause a deterioration in hospital mortality.

OBJECTIVE

To examine the interaction between arrival time (time from onset of chest pain to arrival at hospital) and thrombolytic treatment in determining the early outcome of acute myocardial infarction.

METHODS

Prospective cohort study of 1723 patients with acute myocardial infarction who were potentially eligible for thrombolytic treatment (ST elevation on ECG; arrival time < or = 12 hours).

RESULTS

All patients were eligible for thrombolysis but only 1098 (80%) received it. Patients who did not receive thrombolytic treatment were older (66 (58-73) v 61 (53-70) years, p < 0.001), more commonly female (32.1% v 24.8%, p < 0.01), and had higher frequencies of previous infarction (28.6% v 15.6%, p < 0.001) and left ventricular failure (37.5% v 26.9%, p < 0.01) than patients who received thrombolytic treatment. For the group as a whole, 30 day mortality was 11.7% and was unaffected by arrival time, but in patients who did not receive thrombolysis an arrival time of < or = 6 hours was associated with significantly higher 30 day mortality than an arrival time of 6-12 hours (24.3% v 2.6%, p = 0.002). Conversely, in patients who did receive thrombolysis an arrival time of < or = 6 hours was associated with a lower 30 day mortality than an arrival time of 6-12 hours (8.5% v 14.5%, p < 0.02).

CONCLUSIONS

Shortening prehospital delay in acute myocardial infarction will tend to increase the risk profile of patients presenting to emergency departments. The data presented here indicate that this may increase hospital mortality if underutilisation of thrombolytic treatment among high risk groups is not diminished.

TACHYARRHYTHMIAS ASSOCIATED WITH ACUTE MYOCARDIAL INFARCTION

The occurrence of tachyarrhythmias in the setting of an MI is quite common. As appropriate therapy for the MI is underway, any tachyarrhythmia should be quickly recognized, the cause determined, and appropriate therapy initiated because of instability or before the onset of a cycle of ischemia, begetting tachycardia, begetting more ischemia.

Changes over time in the incidence and case-fatality rates of primary ventricular fibrillation complicating acute myocardial infarction: perspectives from the Worcester Heart Attack Study

BACKGROUND

Limited population-based data are available that describe temporal and recent trends in the incidence and case-fatality rates in patients with primary ventricular fibrillation (VF) complicating acute myocardial infarction (AMI). The purpose of this study was to describe changes over a 22-year period (1975 through 1997) in the incidence and hospital case-fatality rates of primary VF complicating AMI from a multihospital, community-wide perspective.

METHODS AND RESULTS

This was an observational study of metropolitan Worcester residents hospitalized with a validated uncomplicated AMI (n = 5020) in all hospitals in the Worcester, Massachusetts, metropolitan area (1990 census population = 437,000) during 11 1-year periods between 1975 and 1997. The overall incidence rate of primary VF complicating AMI was 4.7%. The crude as well as multivariable adjusted odds of the development of VF did not change significantly over the 22-year period under study. The overall in-hospital case-fatality rate of patients with primary VF was 44%, which was significantly greater in comparison with AMI patients in whom VF did not develop (5%). Hospital mortality rates associated with primary VF declined over time. Improved survival was observed in patients who had primary VF in the 1990s after adjusting for potential prognostic confounders.

CONCLUSIONS

The results of this community-wide study failed to indicate changes over time in the incidence rates of primary VF in patients hospitalized with AMI between 1975 and 1997. On the other hand, hospital death rates in patients with primary VF have shown encouraging declines during more recent periods. These mortality trends are likely to be the results of improvements in the treatment and more careful surveillance of patients with AMI.

Out-of-hospital ventricular fibrillation in patients with acute myocardial infarction: coronary angiographic determinants

OBJECTIVES

The study intended to compare the acute coronary anatomy of patients with acute myocardial infarction (AMI) complicated by out-of-hospital ventricular fibrillation (VF) versus patients with AMI without this complication.

BACKGROUND

More than half of the deaths associated with AMI occur out of the hospital and within 1 h of symptom onset. The angiographic determinants of out-of-hospital VF in patients with AMI have not been investigated in detail.

METHODS

Acute coronary angiographic findings of 72 consecutive patients with AMI complicated by out-of-hospital VF were compared with findings from 144 matched patients with AMI without this complication.

RESULTS

Patients with an acute occlusion of the left anterior descending coronary artery (LAD) or left circumflex coronary artery (LCx) had a higher risk for out-of-hospital VF compared with patients with an acute occlusion of the right coronary artery (RCA) (odds ratio and 95% confidence interval, respectively, 4.82 [2.35 to 9.92] and 4.92 [2.34 to 10.39]). With regard to extent of coronary artery disease (CAD), the location of the culprit lesion in the coronary arteries (proximal vs. mid or distal), the flow in the infarct related artery (IRA), the presence or absence of collaterals to the IRA and chronic occlusions, there were no differences between the two groups.

CONCLUSIONS

Acute myocardial infarction due to occlusion in the left coronary artery (LCA) is associated with greater risk for out-of-hospital VF compared to the RCA. The location of occlusion within LCA (LAD, LCx, proximal or distal), amount of myocardium at risk for necrosis and extent of CAD are not related to out-of-hospital VF.

Prophylactic lidocaine use in acute myocardial infarction: incidence and outcomes from two international trials. The GUSTO-I and GUSTO-IIb Investigators

BACKGROUND

Early meta-analyses suggested that prophylactic lidocaine use reduces ventricular fibrillation but increases mortality rates after acute myocardial infarction. We determined the frequency and effect on clinical outcomes with its use in the thrombolytic era.

METHODS AND RESULTS

We studied 43,704 patients enrolled in GUSTO-I or GUSTO-IIb who had ST-segment elevation, underwent thrombolysis, and survived at least 1 hour after enrollment. Odds ratios (OR) and confidence intervals (CI) were calculated for the risk of asystole, atrioventricular block, ventricular fibrillation, and ventricular tachycardia during hospitalization; for 24-hour, in-hospital, and 30-day mortality rates; and for 24-hour and 30-day mortality rates after adjustment for baseline predictors of death. In GUSTO-I and GUSTO-IIb, 16% and 3.5% of patients, respectively, received prophylactic lidocaine. They had a lower risk of death at 24 hours (OR 0.81, 95% CI 0.67 to 0.97) and trends toward lower odds of in-hospital death (OR 0.90, 95% CI 0.81 to 1.01) and death at 30 days (OR 0.92, 95% CI 0.82 to 1. 02). After adjustment for baseline characteristics, however, the odds of death were similar with or without lidocaine (OR 0.90 and 0. 97, respectively). Outside the United States, lidocaine was associated with higher incidences of all serious arrhythmias, but in US patients it conferred a lower likelihood of ventricular fibrillation and no increase in asystole, atrioventricular block, or mortality rates.

CONCLUSIONS

Prophylactic lidocaine use has decreased with the advent of thrombolysis, although its use may not be associated with increased mortality rates.

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.

Regional expansion during myocardial ischemia predicts ventricular fibrillation and coronary reocclusion

Primary ventricular fibrillation (VF) complicating acute myocardial infarction is associated with occluded infarction-related arteries. The relationship between VF during ischemia and spontaneous coronary reocclusion was analyzed in 48 anesthetized pigs submitted to 48 min of coronary ligation and 6 h of reflow. Reocclusion was associated with ischemic VF (6 of 11 animals with VF but only 6 of 37 without it had reocclusion) but not with reperfusion arrhythmias, the size of the ischemic area, the magnitude of electrocardiogram changes or contractile dysfunction during ischemia, or the severity of intimal injury at the occlusion site. The increase in end-diastolic length in the ischemic region during coronary occlusion was associated with ischemic VF (15 min after occlusion, end-diastolic length was 116 +/- 2 and 111 +/- 1% of baseline in animals with or without presenting subsequent VF, respectively) and was retained by multiple logistic regression analysis as the only independent predictor of ischemic VF and reocclusion. Thus ischemic VF is strongly associated with an increased rate of spontaneous coronary reocclusion during subsequent reperfusion. Acute expansion of ischemic myocardium appears as a prominent determinant of both ischemic VF and reocclusion.

Predisposing factors and prognostic value of sustained monomorphic ventricular tachycardia in the early phase of acute myocardial infarction

OBJECTIVES

The purpose of the study was to analyze the factors that favor the occurrence of sustained monomorphic ventricular tachycardia in the early phase (< 48 h) of acute myocardial infarction and to establish its prognostic implications.

BACKGROUND

Sustained monomorphic ventricular tachycardia early in the course of an acute myocardial infarction is an uncommon arrhythmia, and its significance has not been specifically studied.

METHODS

The clinical characteristics and prognosis of sustained monomorphic ventricular tachycardia were studied in 21 (1.9%) of 1,120 consecutive patients admitted to the coronary care unit with a diagnosis of myocardial infarction.

RESULTS

Patients with sustained monomorphic ventricular tachycardia had a larger infarct on the basis of peak creatine kinase, MB fraction (CK-MB) isoenzyme activity (435 +/- 253 IU/liter vs. 168 +/- 145 IU/liter, p < 0.001) and higher mortality rate (43% vs. 11%, p < 0.001). By logistic regression analysis, independent predictors of sustained monomorphic ventricular tachycardia were CK-MB (odds ratio [OR] 11.8), Killip class (OR 4.0) and bifascicular bundle branch block (OR 3.1). Moreover, sustained monomorphic ventricular tachycardia was itself an independent predictor of mortality (OR 5.0). Compared with patients with ventricular fibrillation, those with sustained monomorphic ventricular tachycardia had a worse Killip class (Killip class > I: 63% vs. 30%, p < 0.05), higher CK-MB activity (430 +/- 260 IU/liter vs. 242 +/- 176 IU/liter, p < 0.01) and higher arrhythmia recurrence rate (31% vs. 4%, p < 0.01). During the follow-up period, 5 (42%) of 12 survivors in the sustained monomorphic ventricular tachycardia group died of cardiac-related causes. Recurrence of ventricular tachycardia was seen in two patients (17%).

CONCLUSIONS

Sustained monomorphic ventricular tachycardia during the first 48 h of myocardial infarction is a sign of extensive myocardial damage and an independent predictor of in-hospital mortality.

Comparison of patients with acute myocardial infarction with and without ventricular fibrillation

Among 1,590 patients with acute myocardial infarction from 1990 to 1994, the rate of primary ventricular fibrillation was 3.6%. The prevalence of smoking, complete left bundle branch block, hypokalemia, and decreased left ventricular function was higher in patients with ventricular fibrillation while those on thrombolytic therapy and those with non-Q-wave myocardial infarction were significantly lower.

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.

Temporal trends (1975 through 1990) in the incidence and case-fatality rates of primary ventricular fibrillation complicating acute myocardial infarction. A communitywide perspective

BACKGROUND

As part of a population-based study of acute myocardial infarction, we examined changes over time in the incidence and in-hospital case-fatality rates of primary ventricular fibrillation complicating acute myocardial infarction.

METHODS AND RESULTS

Patients with validated acute myocardial infarction hospitalized at 16 hospitals in the Worcester, Mass, metropolitan area between 1975 and 1990 comprised the study sample. During the 15-year study period, 5.1% of patients developed primary ventricular fibrillation in the setting of uncomplicated acute myocardial infarction, with this rate remaining relatively constant over time. Both age- and multivariable-adjusted analyses showed no significant trend in the incidence rates of primary ventricular fibrillation during the study period. The in-hospital case-fatality rate for patients with primary ventricular fibrillation was significantly elevated compared with the rate for those without primary ventricular fibrillation and uncomplicated acute myocardial infarction (48.3% versus 1.5%, P < .001). No significant change over time was noted in in-hospital case-fatality rates associated with primary ventricular fibrillation while controlling for a variety of short-term prognostic factors.

CONCLUSIONS

The results of this communitywide observational study suggest that neither the incidence nor the prognosis associated with primary ventricular fibrillation resulting from acute myocardial infarction has improved over time.