Life-threatening Cardiac Events Research Articles

Droperidol, QT prolongation, and sudden death: What is the evidence?

Study objective: Droperidol is a butyrophenone commonly used as an antiemetic and antipsychotic in the United States since US Food and Drug Administration (FDA) approval in 1970. Its labeling has recently been revised, with a black box warning for cases of QT prolongation leading to torsades de pointes and death. A black box warning is applied when serious adverse drug reactions are uncovered for medications. We sought to examine the evidence of a causal association suggested by the black box warning to aid clinicians in their risk-benefit analyses regarding further use of droperidol. Methods: A literature search was undertaken to determine the evidence regarding the association between droperidol and QT prolongation or torsades de pointes. The evidence was then evaluated by using evidence-based medicine principles. In addition, a review of the FDA regulatory process is presented. Results: Three clinical studies, 1 published abstract, and 7 case reports were reviewed. Available postmarketing surveillance data (MedWatch reports) were also reviewed. Applying the criteria of evidence-based medicine and Hill's criteria, the evidence is not convincing for a causal relationship between therapeutic droperidol administration and life-threatening cardiac events. Conclusion: The recent black box warning appears to have originated from postmarketing surveillance data rather than data reported in the peer-reviewed medical literature. Ongoing monitoring of drug safety and more definitive study appear appropriate. [Ann Emerg Med. 2003;41:546-558.]

Psychophysiological Correlates of Peritraumatic Dissociative Responses in Survivors of Life-Threatening Cardiac Events

The psychophysiological startle response pattern associated with peritraumatic dissociation (DISS) was studied in 103 survivors of a life-threatening cardiac event (mean age 61.0 years, SD 13.95). Mean time period since the cardiac event was 37 (79 IQD) months. All patients underwent a psychodiagnostic evaluation (including the Peritraumatic Dissociative Experiences Questionnaire) and a psychophysiological startle experience which comprised the delivery of 15 acoustic startle trials. Magnitude and habituation to trials were measured by means of electromyogram (EMG) and skin conductance responses (SCR). Thirty-two (31%) subjects were indexed as patients with a clinically significant level of DISS symptoms. High-level DISS was associated with a higher magnitude of SCR (ANOVA for repeated measures p = 0.017) and EMG (p = 0.055) and an impaired habituation (SCR slope p = 0.064; EMG slope p = 0.005) in comparison to subjects with no or low DISS. In a subgroup analysis, high-level DISS patients with severe post-traumatic stress disorder (PTSD; n = 11) in comparison to high-level DISS patients without subsequent PTSD (n = 19) exhibited higher EMG amplitudes during all trials (repeated measures analysis of variance F = 5.511, p = 0.026). The results demonstrate exaggerated startle responses in SCR and EMG measures – an abnormal defensive response to high-intensity stimuli which indicates a steady state of increased arousal. DISS patients without PTSD exhibited balanced autonomic responses to the startle trials. DISS may, therefore, unfold malignant properties only in combination with persistent physiological hyperarousability.

Help-seeking Behaviors of Blacks and Whites Dying from Coronary Heart Disease

Objectives : This study sought to determine whether blacks and whites with life-threatening cardiac events differ in likelihood of help seeking, types of help sought, or likelihood of reaching the hospital before death. Design : Death certificates were used to identify all coronary heart disease-related deaths occurring in 1988-89 among 45- to 74-year-old, black and white, non-institutionalized residents of three contiguous inner-city districts in Boston, Massachusetts, USA. An informant was interviewed about the decedent's health status, access to care and pre-mortal help-seeking behaviors. Results : Among the 232 decedents analyzed, there were no racial differences in the likelihood of help seeking. Among those who sought help, there were no racial differences in the likelihood of reaching the hospital. However, blacks were more likely than whites to engage in two specific help-seeking behaviors: calling the 911 emergency system, and trying to reach an emergency room. Conclusion : In an area where blacks and whites were similar with respect to socioeconomic status and access to care, race did not affect the likelihood of help seeking or the likelihood of succeeding in reaching the hospital before death.

Cardiac Biomarkers for Rapid Evaluation of Chest Pain

Physicians caring for acute chest pain patients constantly maneuver between unnecessary admissions and premature discharges. The ECG is the most readily available tool for identifying patients with ST-segment elevation, who are likely to have myocardial infarctions and who should receive reperfusion treatment. Establishing the correct diagnosis in the patients without ST-segment elevation, however, can be much more challenging. Undetected infarctions remain a serious public health issue and represent the leading cause of malpractice cases in the emergency room setting.1 Prematurely discharged patients often have been seen by physicians with less professional experience. Such patients frequently have more atypical complaints and nondiagnostic ECG findings, are younger, and are at higher risk than admitted patients.1,2 See p 1483 Ruling out acute myocardial infarctions, however, is an incomplete strategy according to today’s standards. The target has moved to risk stratification, with the objective being not only to detect evolving myocardial infarctions, but also to identify the patient who is at risk of developing a life-threatening cardiac event in the near future. For this task, the ECG has limited prognostic relevance because abnormalities are infrequent and are of low sensitivity and specificity. Only ST-segment depression, which is found in about one third of the patients, is associated with short- and long-term adverse outcome.3,4 In recent years, novel biochemical markers have emerged that play a pivotal role in diagnosis, risk stratification, and guidance of treatment. Markers of inflammation, such as C-reactive protein, have been found helpful in predicting the long-term prognosis, whereas the improved markers of cell necrosis, mainly cardiac troponins, are valuable tools in the acute phase assessment.5 There is solid evidence from numerous studies that the unstable patient with elevated troponins has an ≈9-fold increased risk for myocardial infarction or death in the next 30 days.6 Consequently, the …

Nonlinear analysis of complex phenomena in cardiological data

The main intention of this contribution is to discuss different nonlinear approaches to heart rate and blood pressure variability analysis for a better understanding of the cardiovascular regulation. We investigate measures of complexity which are based on symbolic dynamics, renormalised entropy and the finite time growth rates. The dual sequence method to estimate the baroreflex sensitivity and the maximal correlation method to estimate the nonlinear coupling between time series are employed for analysing bivariate data. The latter appears to be a suitable method to estimate the strength of the nonlinear coupling and the coupling direction. Heart rate and blood pressure data from clinical pilot studies and from very large clinical studies are analysed. We demonstrate that parameters from nonlinear dynamics are useful for risk stratification after myocardial infarction, for the prediction of life-threatening cardiac events even in short time series, and for modelling the relationship between heart rate and blood pressure regulation. These findings could be of importance for clinical diagnostics, in algorithms for risk stratification, and for therapeutic and preventive tools of next generation implantable cardioverter defibrillators.

Client perceptions of a rural-based cardiac rehabilitation program: a grounded theory approach.

A grounded theory approach was used in an attempt to generate theory about client perceptions and experiences of a cardiac rehabilitation program conducted in a rural community. A series of interviews was conducted with a selection of people who had experienced a life-threatening cardiac event. The cohort was divided into two groups: those who attended a cardiac rehabilitation program and those who did not. The findings, though not generalisable, allowed the generation of a number of theories (which may come to be the genesis of future research) regarding the differences in the physiological, psychological, sociological and vocational well-being between the groups. The findings also suggested that location of the program, the times it was conducted, and the communication skills of significant healthcare workers who recruited participants were important factors affecting attendance.

Chest Pain in an Urban Pediatric Cardiology Practice 133

Evaluation of chest pain is the second most common reason for referral to our pediatric cardiology clinics. Chest pain generates anxiety for patient and parent, as well as frequent diagnostic testing. We sought to determine diagnostic testing patterns and their economic implications in the evaluation of chest pain in children and adolescents. We conducted a retrospective chart review of children and adolescents referred to our practice for initial evaluation of chest pain between 1992 and 1997, who had no pre-existing cardiac conditions. Of 347 children referred, 200 met these criteria. The mean age was 11.5 yrs. (3-19 yrs.), with 51% males. Pertinent past medical history included asthma (17%) and pectoral deformities (2%); pertinent family history included mitral valve prolapse (MVP) (5%), and early sudden death (3%). Chest pain was acute (<1 month) in 15%, chronic in 48%, and of unspecified length in 35%. Other chronic illnesses, primarily asthma, were present in 20%. Associated symptoms were present in 40%; most common were tachycardia (10.5%), dizziness (8%), and palpitations (7%). Chest pain occurred equally with activity and at rest. In only 7 cases (3.5%) was a cardiac abnormality identified: MVP (1%), benign arrhythmia (1.5%), hypertension (0.5%), and small secundum atrial septal defect (0.5%). In only 1 case was the chest pain thought to be related to a cardiac abnormality (mild MVP), and in no case was a serious or life-threatening condition identified. Other causes of chest pain identified included muscloskeletal pain (40.5%), asthma (5%), and obesity(2.5%). All but 1 patient had some diagnostic test: 69 (34.5%) had electrocardiogram (ECG) only; 66 (33%) had ECG and echocardiogram (ECHO),and the remainder had various combinations of ECG, ECHO and a variety of other tests, including Holter monitoring, stress testing, and event monitoring. Total charges were $210,300, or $1,051 per patient, including the outpatient visit, and technical and professional fees for tests performed (except charges for event monitoring, for which complete data were not available). Conclusions: Our data agree with previous studies that chest pain is not a harbinger of serious cardiovascular disease. In general, young patients who have life-threatening cardiac events do not have chest pain as a premonitory symptom. The cost of diagnostic testing in the evaluation of chest pain is high, and the yield is nearly zero. We believe no additional tests are required if the history and physical reveal a non-cardiac origin of chest pain, and that ECG alone should suffice if further testing is desired.

Ability of Heart Rate Variability to Predict Prognosis in Patients With Advanced Congestive Heart Failure

We analyzed heart rate variability from normal RR intervals in patients with advanced congestive heart failure. Although most patients had decreased HRV, patients with a life-threatening cardiac event or death (n = 8) within 18 months had significantly lower heart rate variability than those who did not (n = 18), which may have value in determining prognosis in this population.

CONCERNS IN THE MANAGEMENT OF ANESTHESIA FOR THE PATIENT WITH MYOCARDIAL ISCHEMIA

Patients with coronary artery disease (CAD) may develop symptomatic (angina) or asymptomatic (silent) myocardial ischemia. Perioperative myocardial ischemia in CAD patients can occur secondarily due to hemodynamic aberrations or spontaneously, without hemodynamic changes. Proper preoperative evaluation and preparation followed by aggressive perioperative monitoring and treatment may reduce the incidence of life-threatening cardiac events in these patients. Myocardial ischemia is the event resulting from the insufficient supply of oxygen and nutrients to meet the metabolic demands of the cardiac tissue. Ischemia can be due to a reduction in blood supply or flow, increase in the demand, or usually a combination of both. Ischemia results when blood flow is sufficient for cell life preservation but inadequate for normal physiologic function. Myocardial infarction (MI) results when blood flow is insufficient for cell survival. Ischemia with dysfunction followed by reperfusion before the death of myocardial cells results in stunned myocardium. Chronic low flow states produce hibernating myocardium. 50 The cellular changes resulting from ischemia or infarction produce electrical and functional alterations that can be observed clinically and by using the available monitors. An increased incidence of myocardial infarction following surgery was reported by Randall et al in 1930, 90 Master et al in 1938, 77 Wroblewski et al in 1952, 117 and Topkins et al in 1964. 112 The more recent report of Tarhan et al 108 created the impetus for the extensive research that followed. These more recent studies were performed to correlate the relationship of preoperative, intraoperative, and postoperative myocardial ischemia and the development of serious and life-threatening cardiac events such as myocardial infarction, dysrhythmias, cardiac failure, and death in surgical patients. Keats 45 questioned the conclusions of many of those studies. Do anesthesia and surgery increase the rate of infarction in patients with cad compared with similar patients not undergoing surgery? What is the precipitating event for the development of myocardial infarction? Keats concluded that perioperative ischemia was predictive of postoperative MI, that ischemia was not related to hemodynamic aberrations except tachycardia, preoperative beta-blocker therapy was beneficial, and there was no difference in the outcome between the types of anesthetic agents or techniques used. He also observed that those patients who manifest ischemic changes would have a higher incidence of perioperative MI. In this article, some of the important concepts to understand myocardial ischemia and its relevance to anesthesia and surgery leading to ischemia and perioperative cardiac complications are discussed.

The Quality of Life of Patients With Life-Threatening Arrhythmias

The treatment of life-threatening arrhythmias with amiodarone or an implantable cardioverter/defibrillator prolongs patient survival but with significant comorbidity. Previous studies have shown diminished health status and increased psychologic distress and inferred a diminished quality of life; however, a multidimensional analysis of quality of life, including patient perception, has not been performed. One hundred four consecutive patients were surveyed regarding patient demographics, health status, psychologic distress, and patient-perceived quality of life. The patients were treated with amiodarone (n = 30) with an implantable cardioverter/defibrillator (n = 45) and the remainder were reference patients (n = 29). This study confirms that patients who survive life-threatening arrhythmias have diminished health status and increased psychologic distress; however, patient-perceived quality of life is preserved. These patients report a better perceived quality of life (as measured by the Quality of Life Index) than the reference group (22.3 +/- 4.0 vs 20.5 +/- 4.4, P < .05) and their scores are similar to those of normal healthy volunteers (mean score, 21.9). The improved quality of life scores were not dependent on treatment modality (22.1 +/- 4.0 vs 22.4 +/- 4.1 for medical vs surgical groups, respectively). Patient-perceived quality of life is maintained in patients who survive life-threatening arrhythmias despite their diminished health status and increased psychologic distress. Measured quality of life is independent of treatment modality. Thus, caution must be exercised in assuming a diminished quality of life in patients who have survived a life-threatening cardiac event.

Evaluation of oral and topical administration of ribavirin in herpes zoster : Flores-Guerrero, R. ∗, Dorantes F.J., Garibay-Valencia M., Fortuño-Cordova V., Palacio-Gonzalez M.E. Hospital General de Mexico, SSA, Mexico City, Mexico

Our objective in this study was to evaluate Tpeak-Tend interval (Tp-e) and other electrocardiographic parameters as risk factors for recurrence of life-threatening cardiac events in patients with the Brugada syndrome (BS).The Tp-e interval in the electrocardiogram (ECG) has been reported to predict life-threatening arrhythmias in the long QT syndrome.Twenty-nine patients with the ECG pattern of BS and 29 healthy age- and gender-matched controls were studied. The follow-up period was 42.65 ± 24.42 months (range 11 to 108 months).Upon presentation, five patients had suffered aborted sudden death, five syncope, and two presyncope. Eleven patients with the ECG pattern of BS had a prolonged (>460 ms) QTc in V2but usually not in inferior or left leads. No patient had abnormally prolonged QT dispersion. Programmed electrical stimulation induced ventricular tachycardia/fibrillation in 5 out of 26 patients. Inducibility did not predict recurrence of events. Cardioverter-defibrillators were implanted in 14 patients (all symptomatic and two asymptomatic). During follow-up, nine symptomatic patients experienced recurrences. Previous cardiac events and a QTc >460 ms in V2were significant risk factors (p = 0.00002 and p = 0.03, respectively). Tp-e and Tp-e dispersion were significantly prolonged in patients with recurrences versus patients without events (104.4 and 35.6 ms vs. 87.4 and 23.2 ms; p = 0.006 and p = 0.03, respectively) or controls (90.7 and 17.9 ms; p = 0.02 and p = 0.001, respectively).Our study demonstrates significant correlation between previous events, QTc >460 ms in V2, Tp-e, and Tp-e dispersion and occurrence of life-threatening arrhythmic events, suggesting that these parameters may be useful in risk stratification of patients with the Brugada syndrome.

Prognostic significance of sustained monomorphic ventricular tachycardia induced by programmed ventricular stimulation using up to triple extrastimuli in survivors of acute myocardial infarction

The prognostic significance of sustained monomorphic ventricular tachycardia (VT) induced by programmed ventricular stimulation using up to 3 extrastimuli was evaluated in 133 consecutive survivors of acute myocardial infarction (AMI) at a mean interval of 1.8 ± 1.1 months after onset. This was compared with hemodynamic and angiographic abnormalities shown by cardiac catheterization and ventricular ectopic activity detected by Holter monitoring. Sustained monomorphic VT was induced in 25 (19%) patients, sustained polymorphic VT in 11 (8%) patients, nonsustained monomorphic VT (≥10 beats) in 12 patients (9%) and nonsustained polymorphic VT in 9 patients (7%). Multivariate logistic regression analysis of clinical, angiographic, hemodynamic and electrocardiographic variables showed that the presence of a left ventricular aneurysm (p = 0.005) and Lown grade 4B ventricular ectopic activity (p < 0.001) were independent predictors of inducibility of sustained monomorphic VT. During a mean follow-up of 21 ± 13 months, there were 8 (6%) sudden cardiac deaths and 3 (2.3%) spontaneous occurrences of life-threatening sustained VT. The 2-year probability of freedom from sudden cardiac death or sustained ventricular tachyarrhythmias was 53 ± 13% for patients with inducibte sustained monomorphic VT, 70 ± 10% for those with a left ventricular ejection fraction <40% and 58 ± 13% for those with Lown grade 4B ventricular ectopic activity. Cox regression multivariate analysis revealed only inducibility of sustained monomorphic VT (p < 0.001) and tower left ventricular ejection fraction (p < 0.001) as independent predictors of life-threatening cardiac arrhythmic events, and further, the former predictor was relatively stronger than the latter (coefficient ± standard error, 2.69 ± 0.88 vs −0.12 ± 0.40). Programmed ventricular stimulation with an aggressive stimulation protocol and a strict criterion of abnormal response appeared to be useful to predict the high risk of sudden cardiac death or spontaneous sustained ventricular tachyarrhythmia in survivors of AMI without documented sustained ventricular tachyarrhythmias.

Noninvasive Predictors of Cardiac Events after Myocardial Infarction

Signal-averaged electrocardiography, resting radionuclide ventriculography and Holter monitoring were performed prior to hospital discharge, to assess their value in predicting recurrent cardiac events in 210 survivors of acute myocardial infarction. In addition, 153 of these patients also underwent exercise radionuclide ventriculographic assessment. During median follow-up of 14 months (6-24 months), there were 16 cardiac deaths, 15 patients had recurrent infarction and 7 patients represented with symptomatic ventricular tachycardia. Cox regression analysis identified independent predictors of 'ischemic events' (death or re-infarction) as a previous history of infarction (p = 0.01), Killip class III-IV (p = 0.03) and an abnormal exercise radionuclide study (p = 0.04); and predictors of 'arrhythmic events' (sustained ventricular tachycardia or sudden death) as an abnormal signal-averaged electrocardiograph (p = 0.01) and left ventricular ejection fraction less than 40% (p = 0.03). Patients with an abnormal signal-averaged electrocardiograph and reduced left ventricular ejection fraction had a 34% incidence of arrhythmic events during the first 6 months compared with a 4% incidence among patients without late potentials. In those patients who underwent exercise testing and signal averaging, 85% of total cardiac events and all cardiac deaths were predicted by an abnormality of either noninvasive test. In addition, exercise testing and signal-averaged ECG were independent predictors of outcome. Hence, using a combination of noninvasive tests, patients can be stratified according to the risk of recurrent life-threatening cardiac events after myocardial infarction; such patients may be suitable for intensive investigation and considered for trials involving active intervention.