Frans J. Th. Wackers

Use of the initial electrocardiogram to predict in-hospital complications of acute myocardial infarction.

Abstract We evaluated the initial electrocardiogram as a predictor of complications in 469 patients with suspected acute myocardial infarction. An electrocardiogram was classified as positive if it showed one or more of the following: evidence of infarction, ischemia, or strain; left ventricular hypertrophy; left bundle-branch block; or paced rhythm. Forty-two (14 per cent) of 302 patients with positive electrocardiograms had at least one life-threatening complication (ventricular fibrillation, sustained ventricular tachycardia, or heart block), as compared with 1 (0.6 per cent) of 167 patients with a negative electrocardiogram. Life-threatening complications were therefore 23 times more likely if the initial electrocardiogram was positive (P<0.001). Other complications were 3 to 10 times more likely (P<0.01), interventions were 4 to 10 times more likely (P<0.05), and death was 17 times more likely (P<0.001) in patients with a positive electrocardiogram. We conclude that patients with a negative initial e...

Value and limitations of thallium-201 scintigraphy in the acute phase of myocardial infarction

We examined the diagnostic usefulness of thallium-201 scintigraphy in 200 patients with acute myocardial infarction. The scintiscans showed a defect, suggesting infarction in 165. In all 44 patients studied iwthin six hours after onset of symptoms the scintiscans indicated a defect. Frequency of positive scans was significantly higher (90 of 96) in patients studied within 24 hours after onset than in those (75 of 104) studied later (p less than 0.01).

Location and size of acute transmural myocardial infarction estimated from thallium-201 scintiscans. A clinicopathological study.

A clinicopathological study was performed in 23 patients who died from acute transmural myocardial infarction and who had been studied with thallium-201 during the acute phase. Twenty patients died within five days and three later than five days after scintigraphy. The scintigraphic location and the estimated size of infarction in vivo were correlated with postmortem findings. There was good agreement in 91%percnt; between scintigraphic and postmortem location of infarction and in 70%percnt; between the ECG and postmortem find- ings. The size of infarction as determined from computer-processed schematic drawings of postmortem slices of the heart correlated well with the size determined from processed schematic drawings of the scintiscans (r = 0.91 for anterior infarction, r = 0.97 for inferior infarction, r = 0.86 for anterior-inferior infarction). It is concluded that thallium-201 scintigraphy provided more precise location of infarction than the ECG and that the size of the scintigraphically abnormal area reflected the extent of necrotic myocardium.

Thallium-201 scintigraphy in unstable angina pectoris.

SUMMARYThallium-201 scintigraphy was performed during the pain free period in 98 patients with unstable angina. Scintiscans were positive in 39 patients, questionable in 27 patients and normal in 32 patients. Eighty-one patients responded favorably to treatment (group I). Seventeen patients had complicated courses (group Il) and despite maximal treatment with propranolol either developed infarction (six patients) or continued to have angina necessitating coronary surgery (11 patients). In group I during the pain free period 26 of 81 patients had positive thallium-201 scans, whereas 20 patients had an abnormal ECG at that time; during angina 18 patients had transient ECG changes. In group II during the pain free period 13 of 17 patients had positive scans, whereas two patients had abnormal ECG at that time; during angina 12 patients showed transient ECG changes. The sensitivity to recognize group 11 was 76% for thallium- 201 scintigraphy, 11% for ECG during the pain free period; 70% for ECG during angina; 94% for the combination of either positive scans or abnormal ECG. Thus, 1) positive thallium-201 scans occur in patients with unstable angina, 2) positive scans can be obtained during the pain free period, 3) thallium-201 scans are more frequently positive in patients with complicated course.

Potential value of thallium-201 scintigraphy as a means of selecting patients for the coronary care unit.

The potential value of thallium-201 scintigraphy as a means of selecting patients for appropriate coronary care unit admission was evaluated. Studies were made prospectively on 203 patients with possible acute myocardial infarction but atypical history and non-diagnostic electrocardiogram at a time when the clinical diagnosis was still in doubt. Under conventional circumstances, this particular group of patients will be admitted to the coronary care unit for observation in order to rule out myocardial infarction by further clinical evaluation. Scintigraphy was performed upon arrival in the coronary care unit and within 10 hours after the last episode of chest pain. Of 203 patients, 49 had positive, 47 had questionable, and 107 had normal thallium-201 scintiscans. Serial serum enzyme determinations and further clinical follow-up disclosed acute myocardial infarction in 34 patients: all had abnormal scans. Of47 patients subsequently determined to present with unstable angina, 27 had abnormal scans, ofwhom 7 subsequently developed acute myocardial infarction. Of 24 patients with previous myocardial infarction, 18 patients had abnormal scans. None of either the 25 patients with stable angina or the 73 patients with atypical complaints showed frank perfusion defects, though questionable abnormal scintiscans were obtained in 5 and 12 patients in these groups, respectively. It is concluded that thallium-201 scintigraphy, when performed within a time interval of 10 hours after the last episode ofchest pain, may be ofvalue as a means of selecting those patients requiring further stay in hospital and observation in the coronary care unit.

Sarcoma of the pulmonary trunk associated with hemorrhagic tendency: A case report and review of the literature

The authors present their findings in the case of a man who died with a primary leimyosarcoma of the pulmonary trunk. The tumor extended to the right pulmonary artery, and in both lungs subpleural metastases were noted. The hilar lymph nodes were negative and no distant metastases were found. This is the twentieth reported case in the literature of primary sarcoma of the pulmonary artery, with a different clinical history from the previously reported cases. The difficulty of differentiation, between tumors of the heart base and those arising from the pulmonary artery is discussed.

Thallium-201 Myocardial Imaging in Acute Myocardial Infarction

Thallium-201 scintigraphy has proven to be an early and highly sensitive technique to detect myocardial perfusion abnormalities in patients with acute myocardial infarction [1, 2]. During the early phase of acute myocardial infarction, patients may be hemodynamically and electrically unstable. Therefore, scintigraphy is performed preferably at the bed side in the Coronary Care Unit using a mobile gamma camera. Additionally, in order to shorten imaging time in these often critically ill patients, we recommend injecting no less than 2 mCi of 201T1. Using this dosage, the imaging time per view will be approximately five minutes. Routinely, three views are taken: the first view is a supine 45° left-anterior-oblique view, followed by a supine anterior view and finally a left-lateral view, the latter with the patient turned on the right side[3].

Mechanisms of Thallium-201 Myocardial Accumulation

Thallium is a metallic element of group IIIA of the periodic table with biological similarities to potassium. Thallium was first used successfully for external imaging of the human heart by Kawana et al. [1]. In 1970 these investigators reported on the use of a mixture of short-lived thallium isotopes, mainly 199T1, for myocardial imaging. Lebowitz et al. [2] reported in 1975 the production of 201T1 and suggested that this might be a more favorable isotope for clinical imaging with the Anger scintillation camera. Scintiscans obtained in the goat, indicated that the relative myocardial concentration was sufficient to allow external imaging [3]. In the same year we reported the feasibility of myocardial imaging in patients with and without acute myocardial infarction [4].

Thallium-201 Myocardial Imaging in Unstable Agina and Variant Angina

Scintigraphic myocardial perfusion defects with 201T1 may represent either myocardial infarction or a region of transient ischemia. The results of repeated imaging in patients with acute myocardial infarction suggested that during the initial acute phase, in addition to necrotic tissue, surrounding transient ischemic tissue may be visualized [1]. Moreover, scintigraphic defects, indistinguishable from those seen in (acute) myocardial infarction can be obtained following exercise induced ischemia [2–6] or ischemia resulting from coronary spasm in variant angina [19]. An important portion of coronary care unit admissions includes patients who have repeated episodes of myocardial ischemia, i.e., patients with unstable angina. Therefore, it is of clinical relevance in the coronary care unit to evaluate the potential role of 201T1 scintigraphy in patients with unstable angina. In the present chapter we will discuss 1) the pattern of 201T1 scintigraphy in patients with unstable angina; and 2) the potential predictive value of 201T1 scintigraphy in identifying patients with unstable angina who have a poorer prognosis or greater tendency to subsequently develop acute myocardial infarction. All patients with unstable angina pectoris were purposely studied during the pain free period. It seemed conceivable that injecting 201T1 during an anginal attack would result in a high percentage of scintigraphic defects and probably diminish a potential discriminative value of the method. Moreover, in clinical practice the majority of patients arrive at the coronary care unit some time after the last anginal attack. If a diagnostic test performed at this time could distinguish high and low risk patients, important therapeutic decisions might be made at the earliest possible times.

Thallium-201 Myocardial Imaging as a Selection Method for the Coronary Care Unit

In many patients admitted to the coronary care unit, the diagnosis of acute myocardial infarction is evident at the time of arrival at the hospital. However, among the patients referred to a coronary care unit a significant number has complaints which are determined later not to be caused by acute coronary artery insufficiency. In many of these patients, the history and the initial electrocardiogram will provide sufficient information to recognize the noncar-diac etiology of the complaints. Nevertheless, a substantial group of patients still remains in whom initial evaluation provides a questionable history and a nondiagnostic electrocardiogram : in these patients admission and further observation for at least 24 hours in the coronary care unit seems unavoidable to rule out acute myocardial infarction or ischemia. In order to maximize efficient management and use of the coronary care unit, early and proper characterization of patients in whom the diagnosis remains in question is essential.