Chest pain in the early recognition of large infarcts.

Among 90 patients admitted to hospital with a diagnosis of first myocardial infarction consistent significant associations were found between pain duration, increase in concentration of serum glutamic oxaloacetic transminase (SGOT), maximum temperature and type of infarct (transmural or nontransmural). This suggests that infarct size may be associated with pain duration, increase in SGOT concentration and maximum temperature, and that patients with transmural infarcts have larger infarcts than those with nontransmural infarcts. A higher incidence of premonitory pain -- in particular, premonitory rest pain -- was noted in patients with transmural infarcts, who also had a significantly higher leukocyte count than patients with nontransmural infarcts. Pain intensity was also found to be associated directly with increase in SGOT concentration. However, because intergroup differences were not significant consistently, the association between infarct size, premonitory pain, pain intensity and leukocytosis is less certain. If the association between pain duration and infarct size is confirmed, a simple means would be available for the early recognition of the patient with a large infarct and adverse prognosis who would benefit from prompt therapeutic measures to reduce infarct size.     

Prognostic significance of acute systolic hypertension after myocardial infarction.

The clinical behaviour and mean peak serum aspartate aminotransferase (SGOT) values of 106 patients admitted to a coronary care unit with acute myocardial infarction who displayed acute systolic hypertension were studied. Another 106 normotensive patients with acute myocardial infarction acted as controls. Neither group had established hypertension. The mortality rate, incidence of cardiac failure, major arrhythmias, and mean peak SGOT were significantly greater in the hypertensive group, within which the duration of hypertension was correlated with mean peak SGOT levels--through there was no definite relation between the height of systolic or diastolic pressure and SGOT. Transient systolic hypertension after acute myocardial infarction was therefore associated with a relatively poor prognosis, but our observations suggest that patients with a systolic blood pressure of at least 170 mm Hg might benefit from early hypotensive treatment.     

Shortened bleeding time in acute myocardial infarction and its relation to platelet mass.

The bleeding time, using the Simplate method, horizontal incision, and venostasis, was measured in a study of 51 patients admitted to a coronary care unit within 12 hours of the onset of chest pain. The bleeding time was significantly shorter in the 28 patients who were found to have definite myocardial infarction compared with the 23 others with chest pain but no definite infarction (p less than 0.0005). A bleeding time of less than 212 seconds correctly classified 84% of patients (sensitivity for definite myocardial infarction 89%) presenting to the coronary care unit with chest pain. Multiple regression analysis showed the bleeding time in all patients to be determined independently (and with high significance) by the following variables in order of importance: diagnostic group, platelet mass (platelet count X mean volume), and age. Packed cell volume was not a significant determinant. In the group with definite myocardial infarction considered alone the same order of variables was observed in predicting bleeding time, but none of them was significant. A major variable reducing bleeding time in acute myocardial infarction remains to be determined. There was no association between bleeding time and creatine phosphokinase activity or infarct size in the group with definite myocardial infarction.     

How long should patients with suspected myocardial infarction be under observation in hospital?

Out of 368 patients admitted to hospital for chest pain and suspected acute myocardial infarction, 267 were discharged within 24 hours on the basis of the clinical picture, electrocardiogram, and serum activities of aspartate transaminase, alpha-hydroxybutyrate dehydrogenase, and creatine phosphokinase. The patients were followed up for 28 days, during which 17 were readmitted, two of them twice and one three times. Two of the patients were readmitted with non-fatal acute myocardial infarction, and two died. The patients had been primarily divided into two groups: those admitted with presumably non-coronary chest pain (77 patients) formed group 1 and those with obvious coronary chest pain (190 patients) group 2. Both deaths occurred in patients in group 2 but the incidences of events during the follow-up period were otherwise similar in the two groups, and some patients in both groups may have had small acute myocardial infarctions when first admitted. The decision to keep in hospital or discharge a patient with chest pain of recent onset can be made within 24 hours of admission. To discharge the patient acute myocardial infarction need not necessarily be excluded and conventional tests are enough to enable a decision to be made.     

Is it possible to exclude a diagnosis of myocardial damage within six hours of admission to an emergency department? Diagnostic cohort study

ObjectiveTo assess the clinical efficacy and accuracy of an emergency department based six hour rule-out protocol for myocardial damage.DesignDiagnostic cohort study.SettingEmergency department of an inner city university hospital.Participants383 consecutive patients aged over 25 years with chest pain of less than 12 hours'' duration who were at low to moderate risk of acute myocardial infarction.InterventionSerial measurements of creatine kinase MB mass and continuous ST segment monitoring for six hours with 12 leads.ResultsOutcome of the gold standard test was available for 292 patients. On the diagnostic test for the protocol, 53 patients had positive results and 239 patients had negative results. There were 18 false positive results and one false negative result. Sensitivity was 97.2% (95% confidence interval 95.0% to 99.0%), specificity 93.0% (90.0% to 96.0%), the negative predictive value 99.6%, and the positive predictive value 66.0%. The positive likelihood ratio was 13.9 and the negative likelihood ratio 0.03.ConclusionsThe six hour rule-out protocol for myocardial infarction is accurate and efficacious. It can be used in patients presenting to emergency departments with chest pain indicating a low to moderate risk of myocardial infarction.

What is already known on this topic

Many patients with chest pain in emergency departments indicating a low to moderate risk of myocardial infarction are admitted to rule out myocardial damageSome 6% of those discharged have undiagnosed myocardial damage

What this study adds

An emergency department based chest pain assessment unit protocol to rule out myocardial damage is sensitive enough to allow safe discharge of patients at low to moderate risk of myocardial infarction within six hoursSuch units can also reduce the number of patients admitted unnecessarily     

Survival in acute myocardial infarction; factors observed in 318 patients

Factors influencing survival in a group of 318 cases of acute myocardial infarction were analyzed. The mortality rate for the entire series was 41 per cent. Among the men it was 39.5 per cent; among women, 44.4 per cent. The mortality rate increased with the age of the patient. Twenty-six per cent of all deaths occurred within the first 24 hours, 44 per cent within 72 hours, and 71 per cent within the first week following hospital admission. Increased mortality rate was associated with previous history of congestive failure, myocardial infarction, hypertension or cardiomegaly. As to circumstances immediately preceding an infarction, the only ones that seemed to be related to a high mortality rate were hemorrhage and the postoperative state. Not only the presence but the degree of shock, congestive failure, cyanosis and dyspnea adversely influenced chances for survival. Duration, location, radiation and number of attacks of pain did not appear to be associated with extraordinary mortality rates. Anterior was slightly more common than posterior infarctions, and the mortality rate was much higher. Thromboembolic complications and certain disorders of rhythm and of conduction definitely worsen prognosis. Comparison of average mortality data as reported in different studies on acute myocardial infarction is improper and misleading because of the great differences between the kinds of patients included in various series reported upon. A standard method of grading the severity of acute myocardial infarction would help toward sounder comparisons.     

Prognosis of patients with "chest pain ?cause".

All 662 patients admitted to the two coronary care units in Nottingham during 12 consecutive months were followed up prospectively for one year. At the time of discharge from hospital they were categorised according to set criteria into the following diagnostic groups: definite, probable, or possible myocardial infarction; ischaemia heart disease without infarction; chest pain ?cause; and other diagnoses. Eighty-nine patients (13% of admissions) were categorised as having chest pain ?cause. No deaths occurred among these patients during the observation period, although two were readmitted with myocardial infarction. Patients with chest pain ?cause had few problems during the year after admission, and at the end of that time 75% were in their original employment. Patients admitted with ischaemic heart disease had a similar death rate (between six weeks and one year after admission) to those with myocardial infarction, and only 36% were in their original employment one year after admission. Chest pain ?cause is a clinically useful diagnostic category to which patients may be allocated after only simple investigations.     

Serum and Urinary Enzyme Activity After Renal Infarction

Recently it has been observed that the activity of certain enzymes in serum and urine may be increased after renal infarction. Although aortography or selective renal angiography should be the diagnostic corner-stone on which one would proceed to embolectomy, it is possible that enzyme assays may serve as laboratory aids to suggest or confirm the diagnosis. This paper reviews the few existing clinical and experimental studies and reports on two patients who had a total of three episodes of renal infarction. Serial determinations after one episode showed increased activity of serum oxaloacetic glutamic transaminase (SGOT) and of lactic acid dehydrogenase (LDH) and alkaline phosphatase in the serum and urine; some elevated serum LDH and SGOT values were recorded after the other two infarctions. The time of onset and duration of these increases are discussed, and the possible difficulty in differentiating renal from myocardial infarction is illustrated.     

Guidelines for the use of intravenous thrombolytic agents in acute myocardial infarction. Ontario Medical Association Consensus Group on Thrombolytic Therapy.

A consensus group convened under the auspices of the Ontario Medical Association produced guidelines for the use of intravenous thrombolytic agents in acute myocardial infarction. The guidelines, updated to December 1988, include the following points. 1) Any hospital that routinely accepts the responsibility for looking after patients with acute myocardial infarction could offer thrombolytic therapy if monitoring facilities are available and if the staff are experienced in the treatment of cardiac rhythm disturbances. 2) Before treatment, all patients must be carefully screened for factors predisposing to hemorrhagic complications. 3) A physician should be clearly designated as responsible for the care of the patient receiving an infusion and be available in the event of problems. 4) For the two approved agents the usual dosages are as follows: streptokinase, 1.5 million units given over 1 hour; and tissue-type plasminogen activator (tPA), 100 mg over 3 hours, delivered as 60 mg in the first hour (of which 6 to 7 mg should be given as a bolus in the first 1 to 2 minutes) and then an infusion of 20 mg/h over the next 2 hours. 5) Intravenous thrombolytics should be considered for any patient with presumed acute myocardial infarction, as suggested by prolonged chest pain or other appropriate symptoms and typical electrocardiographic changes. Expeditious treatment is critical, since myocardial necrosis occurs within hours. 6) Emergency angiography is indicated for patients with hemodynamic compromise and no apparent response to streptokinase or tPA and in those with recurrent chest pain suggestive of acute myocardial infarction despite an apparent response to intravenous thrombolysis. Angiography before discharge is recommended for patients with postinfarction angina or evidence from noninvasive testing of significant residual ischemic risk. 7) There is insufficient evidence to choose between streptokinase and tPA on the basis of the two most important outcome measures: patient survival and myocardial preservation. More conclusive evidence comparing tPA, streptokinase and another promising agent, acylated plasminogen-streptokinase activator complex, will be available in 1989-90.     

血清CREG蛋白在急性心肌梗死早期的表达研究

目的：探讨血清中CREG蛋白在急性心肌梗死发作早期的表达情况,尝试为临床心肌缺血的极早期诊断提供一种新的血清标志分子。方法：在2010年6月至2010年11月期间,入选在沈阳军区总医院心内科住院治疗的急性ST段抬高型心肌梗死患者50例及非AMI对照50例,于AMI组胸痛发作后的不同时间点采血测定CK、CK—MB、LDH和cTnT,同时应用Westem blot技术测定血清中CREG蛋白的含量,并与对照组比较。结果：AMI组发病72小时内的血清中CREG蛋白表达均较对照组有不同程度的增高（P〈0．05）。胸痛开始2h内,AMI组血清中CREG的含量即明显增高,其在2h、4h及6h的含量显著高于对照组（P〈0．001）。在胸痛已经发作2小时内,两组间血清cTnT、CK、CK-MB及LDH水平比较无统计学意义（P〉0．05）。结论：CREG在AMI患者血清中的表达增高．其在血清中表达时间早于cTNT及CK-MB。     

Indications for admission to a coronary care unit in patients with unstable angina.

One hundred cases with an admission diagnosis of acute coronary insufficiency or unstable angina were reviewed to establish criteria for admission to a coronary care unit. Myocardial infarction was subsequently diagnosed in 20 of the patients. Ventricular tachycardia occurred in 16 patients and ventricular fibrillation in 1 patient. Clinical features found to predict an increased risk of myocardial infarction included chest pain for more than 30 minutes within 24 hours prior to admission, new nonspecific electrocardiographic abnormalities consistent with ischemia, and diaphoresis. All patients with ventricular tachydysrhythmias had presented with both prolonged chest pain prior to admission and new electrocardiographic changes. The sensitivity, specificity and predictive value of various clinical criteria for identifying patients likely to have a myocardial infarction were calculated, and criteria with very high (greater than 90%) sensitivity were identified. These could be used to establish which patients are at increased risk of myocardial infarction and therefore require admission to a coronary care unit.     

Prospective study of the role of cardiac troponin T in patients admitted with unstable angina.

OBJECTIVE--To examine the prognostic significance and role in risk stratification of the biochemical marker troponin T in patients admitted with unstable angina. DESIGN--Single centre, blinded, prospective study of patients admitted with chest pain. SETTING--Coronary care unit of a district general hospital. SUBJECTS--460 patients admitted with chest pain and followed up for a median of three years. 183 patients had a final diagnosis of unstable angina. MAIN OUTCOME MEASURES--Cardiac death, need for coronary revascularisation, or readmission with non-fatal myocardial infarction as first events. RESULTS--62 (34%) unstable angina patients were troponin T positive. This group had significantly increased incidence rates of subsequent cardiac death (12 cases (19%) v 14 (12%)), coronary revascularisation (22 (35%) v 26 (21%)), death or revascularisation (33 (53%) v 40 (33%)), and death or non-fatal myocardial infarction (18 (29%) v 21 (17%)) compared with the troponin T negative group. In multiple logistic regression troponin T status was a highly significant predictor for the end points coronary revascularisation and cardiac death or revascularisation as first events. CONCLUSION--Troponin T in the serum of patients with unstable angina identifies a subgroup at higher risk of subsequent cardiac events and its measurement aids in risk factor stratification. The increased risk extends to two years after admission. Prospective randomised trials are required to identify optimum therapeutic strategies for this subgroup.     

Chest Pain in Adolescents—Functional Consequences

In prospectively evaluating 100 cases of adolescents with chest pain (along with two control groups), 91 were found to have recurrent chest pain; fewer than 5 had a serious organic cause. Significantly higher school absenteeism occurred in patients with either chest or abdominal pain than in patients without pain. Adolescents with chest and abdominal pain were more likely to be high users of medical services than those with no pain. Most adolescents believed that persons their age could have attacks; 44 of those with chest pain thought their symptom was due to a heart attack. The occurrence of chest pain was not influenced by an adolescent''s age, sex, race, smoking status or family structure, nor was it consistently associated with depression. Chest pain is thus a common problem of adolescence that produces considerable functional impairment not attributable to serious underlying disease.     

Time distribution of the onset of chest pain in subjects with acute ST-elevation myocardial infarction: an eight-year, single-center study in China

Objective

The objective of this study was to explore the time distribution patterns of the onset of chest pain in subjects with acute ST-elevation myocardial infarction in a Chinese population.

Methods

A total of 1467 patients with acute ST-elevation myocardial infarction were enrolled from 2003 to 2010. The hourly, daily, monthly, seasonal and day-of-week fluctuations in the prevalence of acute ST-elevation myocardial infarction were analyzed.

Results

A peak was found between the morning hours of 07:31 and 08:30. A second peak was observed between 14:31 and 15:30, and a third peak was found between 23:31 and 00:30 (p<0.001). The monthly maximum was recorded in November and the minimum was in April (p<0.001). The number of daily cases was greatest in autumn and lowest in the spring (p = 0.001). Day-of-the-week variations of ST-elevation acute myocardial infarction were not found, except in patients more than 75-years-old.

Conclusions

Periodic variations in the frequency of ST-elevation acute myocardial infarction in Chinese patients showed significant differences with regard to diurnal, monthly and seasonal patterns. The exact mechanisms underlying these circadian variations require further study.     

A longitudinal study on BIO14.6 hamsters with dilated cardiomyopathy: micro-echocardiographic evaluation

Background

Acute myocarditis may mimic myocardial infarction, since affected patients complain of "typical" chest pain, the ECG changes are identical to those observed in acute coronary syndromes, and serum markers are increased. We describe a case series of presumptive myocarditis with ST segment elevation on admission ECG.

Methods and Results

From 1998 to 2009, 21 patients (20 males; age 17-42 years) were admitted with chest pain, persistent ST segment elevation, serum enzyme and troponine release. All but one patients had fever and flu-like symptoms prior to admission. No abnormal Q wave appeared in any ECG tracing, and angiography did not show significant coronary artery disease. Patients remained asymptomatic at long term follow-up, except 2 who experienced a late relapse, with the same clinical, electrocardiographic and serum findings as in the first clinical presentation.

Conclusion

Presumptive myocarditis of possible viral origin characterized by ST elevation mimicking myocardial infarction, good short term prognosis and some risk for recurrence is relatively frequent in young males and appears as a distinct clinical condition.     

Prospective evaluation of eligibility for thrombolytic therapy in acute myocardial infarction.

OBJECTIVES--To determine the proportion of patients presenting with acute myocardial infarction who are eligible for thrombolytic therapy. DESIGN--Cohort follow up study. SETTING--The four coronary care units in Auckland, New Zealand. SUBJECTS--All 3014 patients presenting to the units with suspected myocardial infarction in 1993. MAIN OUTCOME MEASURES--Eligibility for reperfusion with thrombolytic therapy (presentation within 12 hours of the onset of ischaemic chest pain with ST elevation > or = 2 mm in leads V1-V3, ST elevation > or = 1 mm in any other two contiguous leads, or new left bundle branch block); proportions of (a) patients eligible for reperfusion and (b) patients with contraindications to thrombolysis; death (including causes); definite myocardial infarction. RESULTS--948 patients had definite myocardial infarction, 124 probable myocardial infarction, and nine ST elevation but no infarction; 1274 patients had unstable angina and 659 chest pain of other causes. Of patients with definite or probable myocardial infarction, 576 (53.3%) were eligible for reperfusion, 39 had definite contraindications to thrombolysis (risk of bleeding). Hence 49.7% of patients (537/1081) were eligible for thrombolysis and 43.5% (470) received this treatment. Hospital mortality among patients eligible for reperfusion was 11.7% (55/470 cases) among those who received thrombolysis and 17.0% (18/106) among those who did not. CONCLUSIONS--On current criteria about half of patients admitted to coronary care units with definite or probable myocardial infarction are eligible for thrombolytic therapy. Few eligible patients have definite contraindications to thrombolytic therapy. Mortality for all community admissions for myocardial infarction remains high.     

Value of infarct-specific isotope (99mTc-labelled stannous pyrophosphate) in myocardial scanning.

With the use of 99mTc-labelled stannous pyrophosphate scans positive for myocardial infarction were obtained from 28 patients in the acute stage of the disease. In some cases the scan was positive when the initial electrocardiogram gave equivocal results. Negative scans were obtained from a control group of patients and from eight patients in hospital with chest pain but with no other evidence of recent myocardial infarction.     

Meteorological factors and the time of onset of chest pain in acute myocardial infarction

Analysis of the time of onset of chest pain in 2254 patients with a myocardial infarction admitted to a coronary care unit in Leicester during a 10-year period shows an association with temperature and humidity. During both the most cold and humid times of the year, the relationship is a strong one. A generalized linear model with a log link was used to fit the data and the backward elimination selection procedure suggested a humid, cold day might help to trigger the occurrence of myocardial infarction. In addition, cold weather was found to have a stronger effect on the male population while those men aged between 50 and 70 years were more sensitive to the effect of high humidity.     

Radioimmunoassay of serum myoglobin in screening for acute myocardial infarction.

Over an 8-month period 289 patients consecutively admitted to a coronary care unit were studied to assess the value of serum myoglobin determinations by radioimmunoassay in screening for acute myocardial infarction. Of the 289 patients 127 (44%) had an infarction. It was found that when blood sampling was done within 5 to 15 hours after the onset of chest pain this assay had a sensitivity, specificity, and positive and negative predictive values of more than 97%. In this study healthy young adults had a mean serum myoglobin level of 37 +/- 11 (standard deviation) ng/ml, and values above 80 ng/ml were considered positive for acute myocardial infarction. False-positive results can be due to stock, vigorous exercise, skeletal muscle damage and several renal failure, but, except for the last one, these conditions also caused an increase in the serum level of the creatine kinase isoenzyme CK-MB.     

Acute Myocardial Infarction and Stress Cardiomyopathy following the Christchurch Earthquakes

Background

Christchurch, New Zealand, was struck by 2 major earthquakes at 4:36am on 4 September 2010, magnitude 7.1 and at 12:51pm on 22 February 2011, magnitude 6.3. Both events caused widespread destruction. Christchurch Hospital was the region''s only acute care hospital. It remained functional following both earthquakes. We were able to examine the effects of the 2 earthquakes on acute cardiac presentations.

Methods

Patients admitted under Cardiology in Christchurch Hospital 3 week prior to and 5 weeks following both earthquakes were analysed, with corresponding control periods in September 2009 and February 2010. Patients were categorised based on diagnosis: ST elevation myocardial infarction, Non ST elevation myocardial infarction, stress cardiomyopathy, unstable angina, stable angina, non cardiac chest pain, arrhythmia and others.

Results

There was a significant increase in overall admissions (p<0.003), ST elevation myocardial infarction (p<0.016), and non cardiac chest pain (p<0.022) in the first 2 weeks following the early morning September earthquake. This pattern was not seen after the early afternoon February earthquake. Instead, there was a very large number of stress cardiomyopathy admissions with 21 cases (95% CI 2.6–6.4) in 4 days. There had been 6 stress cardiomyopathy cases after the first earthquake (95% CI 0.44–2.62). Statistical analysis showed this to be a significant difference between the earthquakes (p<0.05).

Conclusion

The early morning September earthquake triggered a large increase in ST elevation myocardial infarction and a few stress cardiomyopathy cases. The early afternoon February earthquake caused significantly more stress cardiomyopathy. Two major earthquakes occurring at different times of day differed in their effect on acute cardiac events.