Acute Myocardial Infarction: Clinical Application of Technetium 99m Stannous Pyrophosphate Infarct Scintigraphy

Acute myocardial infarction is being recognized as a spectrum of clinical subsets. This appreciation has been brought about to a large degree by the development of several new tools that can be applied clinically to aid in evaluation of patients with acute infarction, and in some cases to provide short and long-term prognostic information. In the realm of noninvasive methods, several tests utilizing radiopharmaceuticals and scintillation cameras have emerged and are rapidly becoming reliable diagnostic parameters in patients with coronary disease and infarction. Technetium 99m (stannous) pyrophosphate (TcPYP) scintigraphy, one of the first of these techniques to find clinical use, has been shown to be an accurate indicator of acute transmural myocardial infarction and provides added sensitivity and specificity to the diagnosis. Increased diagnostic accuracy, the dimension of visible localization and the potential for infarct sizing promise physicians better understanding of a patient''s clinical presentation and a more rational approach to management.     

Evaluation of optimization techniques for variable selection in logistic regression applied to diagnosis of myocardial infarction

Logistic regression is often used to help make medical decisions with binary outcomes. Here we evaluate the use of several methods for selection of variables in logistic regression. We use a large dataset to predict the diagnosis of myocardial infarction in patients reporting to an emergency room with chest pain. Our results indicate that some of the examined methods are well suited for variable selection in logistic regression and that our model, and our myocardial infarction risk calculator, can be an additional tool to aid physicians in myocardial infarction diagnosis.     

Evaluating chest pain in the emergency department.

Chest pain is one of the most difficult diagnostic problems for physicians working in an emergency department. In this setting, more malpractice dollars are awarded for missed myocardial infarction than for any other physician error. This problem usually occurs when the patient has atypical symptoms, the physician is inexperienced, or the diagnosis is not considered. The clinical manifestations of myocardial infarction vary greatly, and patients with "atypical" presentations have a poorer prognosis than those with classic symptoms. Although no feature of a patient''s history excludes infarction with certainty, pain that is sharp, positional, pleuritic, or reproduced by palpation indicates a lower probability of acute ischemic heart disease. New immunochemical methods and serial sampling strategies have increased the sensitivity of creatine kinase-MB as an indicator for the disorder. Recent investigations have also established the prognostic value of the initial electrocardiogram. These methods allow emergency physicians to assess the risk of complications and to perform triage when there is a shortage of beds in the coronary care unit. Emergency physicians must also consider other diseases for which coronary care might be beneficial.     

Early treatment of myocardial infarction in the community.

The prehospital management of acute myocardial infarction by general practitioners and emergency-treatment service physicians was analysed in 53 patients. The correct clinical diagnosis was made or suggested before admission in 47 patients. Only 25 patients received analgesics from the general practitioner, and 32 were still in pain and needed diamorphine on admission to hospital. Only one patient received antiarrythmic treatment. The findings suggest that, despite accurate clinical diagnosis of acute myocardial infarction, deficiencies exist in the prehospital phase of management and that education programmes are worth consideration.     

Comparing Cognitive and Somatic Symptoms of Depression in Myocardial Infarction Patients and Depressed Patients in Primary and Mental Health Care

Depression in myocardial infarction patients is often a first episode with a late age of onset. Two studies that compared depressed myocardial infarction patients to psychiatric patients found similar levels of somatic symptoms, and one study reported lower levels of cognitive/affective symptoms in myocardial infarction patients. We hypothesized that myocardial infarction patients with first depression onset at a late age would experience fewer cognitive/affective symptoms than depressed patients without cardiovascular disease. Combined data from two large multicenter depression studies resulted in a sample of 734 depressed individuals (194 myocardial infarction, 214 primary care, and 326 mental health care patients). A structured clinical interview provided information about depression diagnosis. Summed cognitive/affective and somatic symptom levels were compared between groups using analysis of covariance, with and without adjusting for the effects of recurrence and age of onset. Depressed myocardial infarction and primary care patients reported significantly lower cognitive/affective symptom levels than mental health care patients (F (2,682) = 6.043, p = 0.003). Additional analyses showed that the difference between myocardial infarction and mental health care patients disappeared after adjusting for age of onset but not recurrence of depression. These group differences were also supported by data-driven latent class analyses. There were no significant group differences in somatic symptom levels. Depression after myocardial infarction appears to have a different phenomenology than depression observed in mental health care. Future studies should investigate the etiological factors predictive of symptom dimensions in myocardial infarction and late-onset depression patients.     

Psychological rehabilitation after myocardial infarction.

The value of psychological counselling in rehabilitating patients after myocardial infarction was assessed. A total of 143 men who had recently had a myocardial infarction were randomly allocated to either a group receiving intensive rehabilitation or a control group, their outcome being examined after six months. Patients with neurotic, introverted personalities had a poor outcome in the control group but a satisfactory outcome when rehabilitated. Neurotic personalities responded to help, and rehabilitative measures did not increase neurosis. In addition all patients with a negative attitude towards their illness and future had a poor outcome but those with a positive attitude did well. Selection by simple methods of patients who would benefit from psychological rehabilitation seems desirable.     

心肌酶和红细胞形态学参数与心肌梗死的相关性研究

目的:研究红细胞形态学参数对心肌梗死患者诊断作用及其与心肌酶谱的相关性。方法:选取40例心肌梗死患者,40例稳定型心绞痛组患者,40例健康对照组人群。对比分析稳定性心绞痛、急性心肌梗死(入院1h内)和对照组红细胞形态学参数(MCV、MCH、MCHC、RDW)、及心肌酶谱(CK-MB、c Tn I)。分析心肌梗死不同时间MCV、MCH、MCHC、RDW变化趋势。结果:稳定性心绞痛、心肌梗死组1 h内MCV、RDW明显高于正常对照组,差异有统计学意义(P0.05);稳定性心绞痛、心肌梗死组1 h内MCHC、MCH低于对照组,差异有统计学意义(P0.05)。心肌梗死组MCV、RDW在发病后1 h、24 h、48 h、7 d水平逐渐升高,各时间点间差异有统计学意义(P0.05)。心肌梗死组发病后1 h、24 h、48 h、7 d、14 d MCHC、MCH水平逐渐降低,各时间点间差异有统计学意义(P0.05)。RDW和CK-MB、c Tn I呈正相关性(P0.05)。RDW对心肌梗死诊断的灵敏度最高达到93.4%,特异度为69.7%,RDW对急性心肌梗塞的诊断临界值为14.04%。结论:RDW对心肌梗死的诊断具有较高的敏感性,可用于临床早期诊断心肌梗死,为临床诊断提供一新的诊断标准。     

Changing patterns in drug therapy for ischemic heart disease

To determine the possible influence of studies on β-blocker therapy following myocardial infarction and the introduction of calcium-channel blockers on the prescribing habits of physicians in a large urban centre, the drug therapy received by 100 patients with ischemic heart disease (IHD) (50 with myocardial infarction and 50 with unstable angina) admitted to a university teaching hospital in 1980 was compared with that received by another such group of 100 patients admitted in 1983-84. The proportion of patients with myocardial infarction receiving drug therapy was significantly higher in 1983-84, at the time of both admission (p < 0.01) and discharge (p < 0.001). Much of the increase was due to greater use of β-blockers. Of the 50 patients with unstable angina in 1983-84, 20 were taking calcium-channel blockers when admitted, and 29 were taking them when discharged. In both 1980 and 1983-84 unstable angina was treated more vigorously than myocardial infarction. The results suggest that physicians have developed a more aggressive approach to drug therapy for IHD since the publication of the β-blocker studies and the introduction of calcium-channel blockers.     

Coronary artery thrombosis and elevated urine immunoreactive thromboxane B2

Immunoreactive thromboxane B2 (i-TXB2) was measured by radio-immunoassay (RIA) in urines collected over eight hours on the day of admission in 25 patients who were admitted with the diagnosis of myocardial infarction. In 16 of the patients myocardial infarction was confirmed by ECG and plasma enzymes. Another patient presented with pulmonary embolism and the remaining eight patients had angina pectoris. A further eight hour urine collection was obtained 24 hours later from eleven of the sixteen patients with myocardial infarction. In these eleven patients myocardial infarction was associated with five fold higher urine i-TXB2 (2.72 +/- 0.48 ng/ml) at the day of admission when compared to patients admitted under the same diagnosis but found to have angina only (0.51 +/- 0.08 ng/ml, p less than 0.001). In patients with myocardial infarction the urine i-TXB2 values were reduced 24 hours later (1.58 +/- 0.27 ng/ml, p less than 0.01). One patient was followed with urine i-TXB2 from three days prior to diagnosis of myocardial infarction and to one day prior to a second infarction. In this patient i-TXB2 was highest three days prior to infarction. We conclude that this early elevation of urine i-TXB2 three days prior to diagnosis of infarction and the increased i-TXB2 in patients with myocardial infarction when compared to patients with angina suggest thromboxane is probably released from activated platelets prior to infarction. We suggest that urine i-TXB2 may be of value in the differential diagnosis between myocardial infarction and angina.     

Role of the general practitioner in managing patients with myocardial infarction: impact of thrombolytic treatment. Report of a British Heart Foundation Working Group.

Thrombolytic treatment, combined with aspirin, has been shown to reduce mortality by half in patients in hospital with suspected acute myocardial infarction if it is given early after the onset of symptoms. This fact adds to the importance of prompt and skillful intervention. At present in the United Kingdom the median time for receiving suitable management for this condition is about four to six hours. With better organisation this delay could, in most areas, be reduced to two or three hours. A major change in the care of patients with myocardial infarction is needed in which the general practitioner should have a crucial role. Health authorities, hospital physicians, general practitioners, and the ambulance services must coordinate their efforts if the potential reduction in mortality is to be realised. The district medical officer should consult colleagues and draw up guidelines for organising the care of patients who have had heart attacks. The management of patients who have had heart attacks in the community and in hospital should be continually audited. There are dangers inherent in the use of thrombolytic treatment, particularly when conditions other than myocardial infarction are treated in error. This treatment should be given only when the diagnosis is highly probable and when close observation of the patient can be ensured during the ensuing hours. Thrombolytic treatment should not, therefore, be given out of hospital except when trained, equipped personnel are in attendance. Treatment can be given in any hospital (including community hospitals) provided there are adequate diagnostic facilities and suitably experienced nursing staff.     

Left ventricular aneurysm: Twenty-year surgical experience with 1572 patients at the Texas Heart Institute

From January 1958 through December 1979, 1572 patients underwent surgery for left ventricular aneurysm (LVA) in our institution. The series included 1365 men and 207 women, with a ratio of 6.5:1. Ages ranged from 25 to 79 years, with a mean of 54.7 years. Most patients were in NYHA functional Class III or IV, and all had sustained at least one documented myocardial infarction. During the first decade, LVA resection alone was performed, but after the advent of aortocoronary bypass (ACB) surgery, the majority of patients underwent ACB along with LVA resection. Some required additional septoplasty, mitral valve replacement, annuloplasty, or aortic valve replacement. In all groups, the mortality was higher for women than for men. Early deaths were due primarily to acute or progressive myocardial failure secondary to recurrent myocardial infarction. Follow-up information for 6 months to 8 years was obtained by means of questionnaires submitted to patients and referring physicians. Of 475 patients who underwent LVA resection and ACB and who responded, 92.2% were either improved or asymptomatic.     

A somatic component to myocardial infarction.

Sixty two patients were randomised to be seen by osteopathic physicians for palpation of the thoracic paravertebral soft tissue, T1-T8. Twenty five patients had clinically confirmed acute myocardial infarction. Of the remainder, 22 without known cardiovascular disease served as controls and 15 were placed in an excluded group because of diagnosed cardiovascular disease other than myocardial infarction. Observations were described in predetermined standard terminology. The control group was found to have a low incidence of palpable changes throughout the thoracic dorsum, and these changes were uniformly distributed from T1 to T8. Examination of the group with myocardial infarction disclosed a significantly higher incidence of soft tissue changes (increased firmness, warmth, ropiness, oedematous changes, heavy musculature), confined almost entirely to the upper four thoracic levels. The 15 patients who were excluded from the experimental group because they had various cardiovascular diseases other than myocardial infarction also showed significantly different changes on palpation compared with the group with myocardial infarction. These findings suggest that myocardial infarction is accompanied by characteristic paravertebral soft tissue changes which are readily detected by palpation.     

Coronary artery thrombosis and evaluated urine immunoreactive thromboxane B2

Immunoreactive thromboxane B₂ (i-TXB₂) was measured by radio-immunoassay (RIA) in urine collective over eight hours on the day of admission in 25 patients who were admitted with the diagnosis of myocardial infarction. In 16 of the patients myocardial infarction was confirmed by ECG and plasma enzymes. Another patient presented with pulmonary embolism and the remaining eight patients had angina pectoris. A further eight hour urine collection was obtained 24 hours later from eleven of the sixteen patients with myocardial infarction. In these eleven patients myocardial infarction was associated with five fold higher urine i-TXB₂ (2.72 ± 0.48 ng/ml) at the day of admission when compared to patients admitted under the same diagnosis but found to have angina only (0.51 ± 0.08 ng/ml, p < 0.001). In patients with myocardial infarction the urine i-TXB₂ values were reduced 24 hours later (1.58 ± 0.27 ng/ml, p < 0.01). One patient was followed with urine i-TXB₂ from three days prior to diagnosis of myocardial infarction and to one day prior to a second infarction. In this patient i-TXB₂ was highest three days prior to infarction. We conclude that this early elevation of urine i-TXB₂ three days prior to diagnosis of infarction and the increased i-TXB₂ in patients with myocardial infarction when compared to patients with angina suggest thromboxane is probably released from activated platelets prior to infarction. We suggest that urine i-TXB₂ may be of value in the differential diagnosis between myocardial infarction and angina.     

Cardiac predictors of death after non-cardiac surgery evaluated by intention to treat.

Cardiac risk factors were studied among patients who were admitted to hospital with appendicitis or a fracture of the proximal femur less than one year after being admitted with myocardial infarction. Of 99 patients with myocardial infarction and appendicitis, 87 underwent appendicectomy; and of 221 with myocardial infarction and hip fracture, 179 were operated on. The patients were studied on an intention to treat basis. The mortality within one month was 9% and 16% respectively. A history of congestive heart failure was the dominating risk factor, while ischaemic heart disease (recent myocardial infarction or angina pectoris) had no independent association with mortality. If the ventricular function is known additional preoperative information about the heart is of negligible value when estimating the mortality of non-cardiac surgery.     

The fate of young individuals with a history of myocardial infarction]

The fate of young individuals (to 45 years) with a history of myocardial infarction during 12 years was analysed with the aid of a questionnaire containing questions of both social and medical character. Sudden cardiac death or the second infarction were the most frequent causes of death during the first two years following myocardial infarction. Change in the physical activity mainly involved the return to work. Only 47% of young men and 29.8% of women started full-time jobs. They mainly belonged to so-called white collars. The lack of patients' physicians permission was a main cause of the abstinence of young men from the occupation. A position within the family and social activity usually remained unchanged in the majority of patients, but every third patient greatly reduced sexual activity. Every third patients continued smoking, and did not observe recommended diet despite the systematical medical check-ups. The course of the disease is unclear in the majority of young patients. It is often deformed and requires further, detailed information on young patients' style of life.     

Trial of early nifedipine in acute myocardial infarction: the Trent study.

Over 30 months 9292 consecutive patients admitted to nine coronary care units with suspected myocardial infarction were considered for admission to a randomised double blind study comparing the effect on mortality of nifedipine 10 mg four times a day with that of placebo. Among the 4801 patients excluded from the study the overall one month fatality rate was 18.2% and the one month fatality rate in those with definite myocardial infarction 26.8%. A total of 4491 patients fulfilled the entry criteria and were randomly allocated to nifedipine or placebo immediately after assessment in the coronary care unit. Roughly 64% of patients in both treatment groups sustained an acute myocardial infarction. The overall one month fatality rates were 6.3% in the placebo treated group and 6.7% in the nifedipine treated group. Most of the deaths occurred in patients with an in hospital diagnosis of myocardial infarction, and their one month fatality rates were 9.3% for the placebo group and 10.2% for the nifedipine group. These differences were not statistically significant. Subgroup analysis also did not suggest any particular group of patients with suspected acute myocardial infarction who might benefit from early nifedipine treatment in the dose studied.     

Value of positive myocardial infarction imaging in coronary care units.

Positive myocardial imaging was undertaken on 120 unselected patients admitted to a coronary care unit with clinical suspicion of acute myocardial infarction. Multipurpose mobile gamma-cameras were used for serial imaging after administration of 99mtechnetium-labelled imidodiphosphonate, a low-cost radiopharmaceutical that is 97% specific for myocardial necrosis, with myocardial uptake and blood clearance most suitable for myocardial imaging. The sensitivty of detection was 94% for patients whose infarction was unequivocal on the ECG; when the presence of raised enzyme concentrations was also used as a criterion for myocardial necrosis, the overall sensitivity for all 120 patients remained 94%. In 73 patients (61%), whose ECGs were unhelpful or difficult to interpret, scintigraphy allowed infarction to be diagnosed in 11 (15%) and to be excluded in five (7%). In 32 (44%) of this group whose ECGs were totally uninterpretable due to previous myocardial damage or disorders of electrical activation, scintigraphy provided confirmation of a diagnosis that otherwise rested only on whether enzyme concentrations were raised. Myocardial imaging is thus a useful technique that permits more definite diagnosis in patients for whom ECG and enzyme data are uncertain.     

Diagnostic re-classification and prognostic risk stratification of patients with acute chest pain

Unstable angina and myocardial infarction are prevalent manifestations of acute coronary artery disease, combined in the term ‘acute coronary syndromes’. The introduction of sensitive markers for myocardial necrosis has led to confusion regarding the distinction between small myocardial infarctions and ‘true’ unstable angina, and the application of ever more sensitive markers has accelerated the pace at which patients with unstable angina are being re-classified to non-ST-segment elevation myocardial infarction. But in how many patients with acute chest pain is myocardial ischaemia really the cause of their symptoms? Numerous studies have shown that most have <5 ng/l high-sensitivity cardiac troponin, and that their prognosis is excellent (event rate <0.5% per year), incompatible with ‘impending infarction’. This marginalisation of patients with unstable angina pectoris should lead to the demise of this diagnosis. Without unstable angina, the usefulness of the term acute coronary syndromes may be questioned next. It is better to abandon the term altogether and revert to the original diagnosis of thrombus-related acute coronary artery disease, myocardial infarction. A national register should be the next logical step to monitor and guide the application of effective therapeutic measures and clinical outcomes in patients with myocardial infarction.

     

Erectile dysfunction after myocardial infarction--myth or a real problem?

Erectile dysfunction is a common problem whose relation to cardiovascular diseases has scientifically been proved, but it has not been studied sufficiently in patients recovering from myocardial infarction. The objective of this study was to establish the frequency of erectile dysfunction in patients recovering from myocardial infarction. We examined 89 patients (aged 30 to 75 years) included in the program of cardiac rehabilitation after myocardial infarction. The results were compared with 91 healthy examinees of the same age. Even 82% of the patients who recovered from myocardial infarction have problems with erectile dysfunction, compared to 42.9% of healthy examinees. The prevalence of erectile dysfunction increases with the age in both groups. In the group of patients recovering from myocardial infarction aged 30 do 39 years, the erectile dysfunction decreased after 6 months, while in other age subgroups and between controls, there were no significant changes in erectile dysfunction prevalence during the analysed time period. We concluded that erectile dysfunction is a significant problem in patients recovering from myocardial infarction. It should be recognized on time in order to provide a better life quality for the patient with a multidisciplinary approach.     

Chronological Changes in Japanese Physicians' Attitude and Behavior Concerning Relationships with Pharmaceutical Representatives: A Qualitative Study

Background

Recent qualitative studies indicated that physicians interact with pharmaceutical representatives depending on the relative weight of the benefits to the risks and are also influenced by a variety of experiences and circumstances. However, these studies do not provide enough information about if, when, how and why their attitudes and behaviors change over time.

Methods and Findings

A qualitative study using semi-structured face-to-face individual interviews was conducted on 9 Japanese physicians who attended a symposium on conflicts of interest held in Tokyo. Interviews were designed to explore chronological changes in individual physicians'' attitude and behavior concerning relationships with pharmaceutical representatives and factors affecting such changes. Their early interaction with pharmaceutical representatives was passive as physicians were not explicitly aware of the meaning of such interaction. They began to think on their own about how to interact with pharmaceutical representatives as they progressed in their careers. Their attitude toward pharmaceutical representatives changed over time. Factors affecting attitudinal change included work environment (local regulations and job position), role models, views of patients and the public, acquisition of skills in information seeking and evidence-based medicine, and learning about the concepts of professionalism and conflict of interest. However, the change in attitude was not necessarily followed by behavioral change, apparently due to rationalization and conformity to social norms.

Conclusions

Physicians'' attitudes toward relationships with pharmaceutical representatives changed over time and factors affecting such changes were various. Paying attention to these factors and creating new social norms may be both necessary to produce change in behavior consistent with change in attitude.