A community survey of the potential use of thrombolytic agents for acute myocardial infarction

Pain modulation efficiency delays seeking medical help in patients with acute myocardial infarction

Rapid reperfusion is crucial to reduce mortality in patients with ST elevation myocardial infarction. Prehospital patient delay, defined as time from symptoms onset to the decision to seek medical attention, accounts for a large proportion of cases with delayed reperfusion. However, whether pain modulation processes are involved in this phenomenon is not known. We hypothesized that prehospital patient delay may be affected by a reduction of perceived pain perception and pain modulation pattern. Pain threshold, magnitude estimation of suprathreshold stimulation, mechanical temporal summation and conditioned pain modulation (CPM), and recalls of pain magnitude at the onset of chest pain were obtained in 67 patients with first ST elevation myocardial infarction. The study's primary outcome was prehospital patient delay. The median patient delay was 24 (interquartile range, 0.5-72) hours. Of all psychophysical pain measures including pain threshold, magnitude estimation of suprathreshold stimulation, mechanical temporal summation, as well as CPM, only warm sensation threshold was independently associated with lower clinical chest pain intensity (P = 0.01). Multivariable regression analysis (R = 0.449; P < 0.0001) revealed an inverse independent association between chest pain intensity (P < 0.001) and patient delay, whereas efficient CPM was positively associated with prolonged patient delay (P = 0.034). The electrocardiography-derived myocardial ischemic area was not associated with chest pain intensity or patient delay, indicating that the affected ischemic tissue is not a dominant component that determines pain response. In conclusion, beyond the perceived chest pain intensity, the activation pattern of descending inhibition pathways during coronary occlusion affects pain interpretation and behavior during acute coronary occlusion.

Factors that impact upon the time to hospital presentation following the onset of chest pain

INTRODUCTION

Although morbidity and mortality associated with chest pain are related to time to intervention, many patients have delayed ED presentations. We aimed to assess the extent of and reasons for prehospital delay, and identify patient subgroups more at risk of delayed presentation.

METHODS

This was an analytical, cross-sectional survey of patients with undifferentiated, potentially ischaemic chest pain, at a tertiary referral ED. Data were collected on the circumstances surrounding the chest pain incident (including components of total prehospital time) and the proportion of delayed presentations (defined as >3 h). Multiple linear regression determined variables significantly associated with prehospital time.

RESULTS

One hundred and fifty patients were enrolled. Mean age was 51.9+/-15.9 years and 90 (60.0%, 95% CI 51.7-67.8) were male. The mean total prehospital time was 6.38 h (median 3.17). Seventy-nine (52.7%, 95% CI 44.4-60.8) patients had a delayed presentation (>3 h) and those most at risk of this were those at home at pain onset and those with a history of AMI. The decision time (from onset of pain to decision to present) comprised the majority (82.8%) of total prehospital time. Factors positively associated with decision time were: waiting to see if symptoms resolved (P<0.0001), seeking GP advice (P<0.0001), fluctuating symptoms (P=0.02), embarrassment (P=0.01) and attributing symptoms to muscle problems (P=0.04). Nine patients diagnosed with AMI had a mean total prehospital time of 10.2 h.

CONCLUSION

Intensified efforts are required to promote awareness of the need to present directly to the ED upon the onset of chest pain. The factors associated with decision delay may help to inform revisions in public education initiatives.

Demographic, belief, and situational factors influencing the decision to utilize emergency medical services among chest pain patients. Rapid Early Action for Coronary Treatment (REACT) study

BACKGROUND

Empirical evidence suggests that people value emergency medical services (EMS) but that they may not use the service when experiencing chest pain. This study evaluates this phenomenon and the factors associated with the failure to use EMS during a potential cardiac event.

METHODS AND RESULTS

Baseline data were gathered from a randomized, controlled community trial (REACT) that was conducted in 20 US communities. A random-digit-dial survey documented bystander intentions to use EMS for cardiac symptoms in each community. An emergency department surveillance system documented the mode of transport among chest pain patients in each community and collected ancillary data, including situational factors surrounding the chest pain event. Logistic regression identified factors associated with failure to use EMS. A total of 962 community members responded to the phone survey, and data were collected on 875 chest pain emergency department arrivals. The mean proportion of community members intending to use EMS during a witnessed cardiac event was 89%; the mean proportion of patients observed using the service was 23%, with significant geographic differences (range, 10% to 48% use). After controlling for covariates, non-EMS users were more likely to try antacids/aspirin and call a doctor and were less likely to subscribe to (or participate in) an EMS prepayment plan.

CONCLUSIONS

The results of this study indicate that indecision, self-treatment, physician contact, and financial concerns may undermine a chest pain patient's intention to use EMS.

Gender differences in reported symptoms for acute myocardial infarction: impact on prehospital delay time interval

A retrospective observational study using database registry of consecutive patients admitted to 16 King County hospital Coronary Care Units (CCU) was conducted to assess gender differences in symptom presentation for acute myocardial infarction (AMI) and investigate how symptom presentation relates to prehospital delay time interval from acute symptom onset to emergency department (ED) presentation. Between January 1991 and February 1993, 4,497 patients were admitted to the CCUs with diagnosed AMI. Accredited record technicians abstracted age, gender, race, transport method, symptom presentation (chest pain, sweating, nausea, shortness of breath, epigastric pain, and fainting), delay time interval between acute symptom onset and presentation to hospital ED, and discharge diagnosis from the patients' medical records. After adjusting for age and history of diabetes, no gender differences remained for frequencies of chest pain, fainting, or epigastric pain. Women reported more nausea and shortness of breath but less sweating than men as symptoms of AMI. Chest pain, sweating, and fainting were associated with decreasing delay time intervals. Age, gender, histories of AMI and diabetes, and transport choice were also significantly related to delay time interval. These results show that gender differences occur in AMI symptom experience. However, how symptoms relate to the gender gap in delay time interval is not clear. These findings suggest that health care professionals need to tailor information about possible symptoms of AMI to the patient's gender, age, and medical history.

Early intravenous thrombolysis in acute myocardial infarction: the Jerusalem experience

Myocardial damage in acute myocardial infarction is a time-dependent process. We examined the influence of very early thrombolytic therapy, comparing prehospital to hospital administration, in a consecutive group of patients with myocardial infarction on mortality, complications and the preservation of left ventricular function. Seven hundred sixty patients received early thrombolytic therapy: 114 at home (time delay to treatment 1.4 +/- 0.8 h) and 646 in hospital (2.1 +/- 1.0 h). Sixteen patients died in hospital and significant hemorrhage occurred in 15 (including three patients with hemorrhagic stroke). There was no difference between groups in hospital mortality or rate of complications. The duration of ischemia was shorter in patients with prehospital therapy (pain duration: 3.3 +/- 2.1 vs. 4.0 +/- 2.2; P < 0.05, and time to recovery of the ST segment in the electrocardiogram: 4.3 +/- 3.3 vs. 6.6 +/- 6.3; P < 0.002). Peak plasma creatine kinase was earlier in patients with prehospital therapy (11.2 +/- 5.0 vs. 13.0 +/- 5.8; P < 0.002), although there was no difference between groups in the absolute peak plasma level. Left ventricular function was assessed by contrast ventriculography 1 week after admission (616 patients). Ventricular function was better in patients with prehospital therapy: (ejection fraction of 58 +/- 13% vs. 54 +/- 15%; P < 0.05 and a left ventricular dysfunction index of 534 +/- 515 vs. 691 +/- 519 units; P < 0.05). We conclude that prehospital thrombolytic therapy is feasible and safe. Reperfusion is achieved earlier and more myocardium can be salvaged using this strategy without increasing the rate of complications.

Utilization of emergency medical services for symptoms of acute myocardial infarction

OBJECTIVE

To examine patient characteristics and situational and clinical factors that affect utilization of Emergency Medical Services (EMS) for symptoms of acute myocardial infarction (AMI).

DESIGN

Telephone interview of patients hospitalized with suspected AMI.

SETTING

Nine hospitals in King County, Washington.

PATIENTS

Patients admitted to a coronary or intensive care unit between October 1, 1986, and December 31, 1987, with suspected AMI occurring out of hospital. Spouses of patients who met criteria but died during the hospitalization also participated.

OUTCOME MEASURES

Patient demographics, coping strategies, situational factors, prior cardiac history, perceived symptom severity, belief about the nature of condition, and method of transportation.

RESULTS

Descriptive statistics showed that although few patients called EMS as a "first thing" in response to symptoms, almost half of all patients called EMS before being hospitalized. Stepwise logistic regression analyses revealed that being older, the belief that one was experiencing a heart attack, the presence of other people (including the spouse), and the lack of physical activity at time of symptom onset, were related to both greater and quicker utilization of EMS. Additionally, education, medical history of angina, and severity of symptoms also were related to utilization of EMS.

CONCLUSION

The findings are discussed in a theoretical context, using Leventhal's self-regulatory model to suggest avenues for future research and interventions.

Impact of direct mail intervention on knowledge, attitudes, and behavioral intentions regarding use of emergency medical services for symptoms of acute myocardial infarction

This study evaluated a direct mail intervention called the "Call Fast, Call 911" campaign designed to increase use of emergency medical services for symptoms of acute myocardial infarction. The campaign was targeted at individuals over the age of 50. Persons over 50 years of age (N = 130,000) in King County, Washington, were randomly assigned to intervention or control groups. Individuals in the intervention groups received six direct mail pieces over a 1-year period encouraging them to call 911 quickly in response to chest pain. A postintervention telephone survey of a random sample of households (N = 434) assessed the impact of the campaign on knowledge, attitudes, and behavioral intentions regarding use of emergency medical services for symptoms of acute myocardial infarction. The results showed no significant differences between intervention and control groups in terms of knowledge of AMI. However, there were significant differences in beliefs and behavioral intentions to call 911 in a cardiac emergency.

Is there an age limit for thrombolytic therapy?

Thrombolytic therapy has revolutionized the treatment of acute myocardial infarction. The mortality of infarction increases very steeply with increasing age > 65 years. One-month mortality in such patients is in the range of 20-30%. The proportional benefit of lytic treatment is somewhat less in these older patients, but since mortality is high, the absolute benefit is as large or larger than that in younger patients. The risks of stroke due to thrombolysis are balanced between increased risk of cerebral hemorrhage but decreased risk for ischemic/embolic stroke. This trade-off results, overall, in a slightly increased stroke rate of about 1-2 per 1,000 nonfatal strokes, but with about 20 fewer deaths per 1,000 myocardial infarctions. In addition to these striking mortality benefits, there are also important reductions in infarct size, leading to decreased morbidity from heart failure or arrhythmias.

Prehospital delay interval for patients who use emergency medical services: the effect of heart-related medical conditions and demographic variables

STUDY OBJECTIVE

To investigate the effect of heart-related medical conditions and demographic variables on patients' tendency to delay contacting emergency medical services for symptoms of acute myocardial infarction.

TYPE OF PARTICIPANTS

A sample of 2,947 patients with acute myocardial infarction but no cardiac arrest, transported by paramedics to the coronary care units of 19 hospitals in King County, Washington, between January 1988 and April 1991.

MEASUREMENTS

Patient record abstracts contained information on medical history, age, gender, delay interval, and means of transportation.

RESULTS

Multiple regression analyses showed that prehospital delay interval was significantly greater for individuals who were older and female and who had a history of angina, congestive heart failure, or diabetes.

CONCLUSION

It is important to investigate further how people interpret and evaluate their symptoms in light of other medical conditions. It is also critical to find out why women delay longer than men and why older individuals delay longer than younger people before they contact emergency medical services. Interventions need to be developed that are targeted at populations at risk for delaying use of emergency medical services for acute myocardial infarction symptoms. These interventions must legitimize the use of emergency medical services and encourage patients to act quickly when confronted with acute myocardial infarction symptoms.

Efficiency of a physician-operated mobile intensive care unit for prehospital thrombolysis in acute myocardial infarction

The efficiency of an emergency medical system for routinely performed prehospital thrombolysis is evaluated for 1 of the 7 physician-staffed mobile intensive care units (MICU) in former West Berlin. During 19 consecutive months the MICU had 4,920 missions, and 1,226 patients had chest pain of presumed cardiac origin. The diagnosis at hospital discharge was acute myocardial infarction (AMI) in 406 patients and "interrupted" infarction in 11 patients (total 417). Correct on-scene electrocardiographic diagnosis of acute injury was made in 268 patients (64%) and was false-positive in 4 patients (1%). In 8%, present ST elevations were not recognized. In 27%, the electrocardiogram on scene was nondiagnostic (16% with no ST elevation, 11% with bundle branch block). Of all 417 patients with later hospital evidence of AMI, 317 (76%) were seen by the MICU physician within 4 hours, and 173 (41%) within the first hour from symptom onset. Two hundred three patients seen within 4 hours had diagnostic ST elevation on the scene, of whom 124 (61%) received prehospital thrombolysis (74 patients [36%] within the first hour). There was no prehospital death; hospital mortality was 6.3%. Because greater than 50% of all patients in the community, hospitalized because of AMI, made use of the MICU and 3/4 of them had called within 4 hours from symptom onset, a large proportion of all patients with AMI were candidates for the actually received prehospital thrombolysis.

Effect of age on use of thrombolytic therapy and mortality in acute myocardial infarction. The MITI Project Group

The findings in 3,256 consecutive patients hospitalized for acute myocardial infarction were tabulated to assess the history, treatments and outcome in the elderly; 1,848 patients (56%) were greater than 65 years of age, including 28% who were aged greater than or equal to 75 years. The incidence of prior angina, hypertension and heart failure (only 3% of patients less than 55 years of age had a history of heart failure compared with 24% greater than or equal to 75 years old) was found to increase with age. Twenty-nine percent of patients less than 75 years of age were treated with a systemic thrombolytic drug compared with only 5% of patients older than 75 years. Mortality rates increased strikingly with advanced age (less than 2% in patients less than or equal to 55, 4.6% in those 55 to 64, 12.3% in those 65 to 74 and 17.8% in those greater than or equal to 75 years). Both the incidence of complicating illness and a nondiagnostic electrocardiogram (ECG) increased with age. In a multivariate analysis of outcome in older patients (greater than or equal to 65 years), adverse events were related to both prior history of heart failure (odds ratio 3.9) and increasing age (odds ratio 1.4 per each decade of age). Outcome was not improved by treatment with thrombolytic drugs, but these agents were prescribed to only 12% of patients greater than 65 years of age, thereby reducing the power for detecting such an effect.(ABSTRACT TRUNCATED AT 250 WORDS)