Myocardial perfusion scintigraphy: the evidence.

This review summarises the evidence for the role of myocardial perfusion scintigraphy (MPS) in patients with known or suspected coronary artery disease. It is the product of a consensus conference organised by the British Cardiac Society, the British Nuclear Cardiology Society and the British Nuclear Medicine Society and is endorsed by the Royal College of Physicians of London and the Royal College of Radiologists. It was used to inform the UK National Institute of Clinical Excellence in their appraisal of MPS in patients with chest pain and myocardial infarction. MPS is a well-established, non-invasive imaging technique with a large body of evidence to support its effectiveness in the diagnosis and management of angina and myocardial infarction. It is more accurate than the exercise ECG in detecting myocardial ischaemia and it is the single most powerful technique for predicting future coronary events. The high diagnostic accuracy of MPS allows reliable risk stratification and guides the selection of patients for further interventions, such as revascularisation. This in turn allows more appropriate utilisation of resources, with the potential for both improved clinical outcomes and greater cost-effectiveness. Evidence from modelling and observational studies supports the enhanced cost-effectiveness associated with MPS use. In patients presenting with stable or acute chest pain, strategies of investigation involving MPS are more cost-effective than those not using the technique. MPS also has particular advantages over alternative techniques in the management of a number of patient subgroups, including women, the elderly and those with diabetes, and its use will have a favourable impact on cost-effectiveness in these groups. MPS is already an integral part of many clinical guidelines for the investigation and management of angina and myocardial infarction. However, the technique is underutilised in the UK, as judged by the inappropriately long waiting times and by comparison with the numbers of revascularisations and coronary angiograms performed. Furthermore, MPS activity levels in this country fall far short of those in comparable European countries, with about half as many scans being undertaken per year. Currently, the number of MPS studies performed annually in the UK is 1,200/million population/year. We estimate the real need to be 4,000/million/year. The current average waiting time is 20 weeks and we recommend that clinically appropriate upper limits of waiting time are 6 weeks for routine studies and 1 week for urgent studies.

Transient disappearance of left bundle branch block pattern: an unusual ECG presentation of acute pulmonary embolism.

A 61 year old man developed acute pulmonary embolism while in hospital. His previous and admission electrocardiograms (ECGs) showed a typical left bundle branch block (LBBB) pattern. Immediately after the onset of acute pulmonary embolism, LBBB disappeared from his body surface ECG with sinus bradycardia, normalisation of QRS duration, prolonged QT interval, and marked T abnormalities to the right precordial leads. Recovery from pulmonary embolism resulted in reappearance of his left bundle branch pattern. Delayed conduction of the previously unaffected right bundle branch resulting in roughly equivalent onset of ventricular activation is the most likely reason. Rate dependent LBBB is also discussed.

Changes in cardiorespiratory fitness, psychological wellbeing, quality of life, and vocational status following a 12 month cardiac exercise rehabilitation programme.

OBJECTIVE: To examine and evaluate improvements in cardiorespiratory fitness, psychological wellbeing, quality of life, and vocational status in postmyocardial infarction patients during and after a comprehensive 12 month exercise rehabilitation programme. SUBJECTS: The sample population comprised 124 patients with a clinical diagnosis of myocardial infarction (122 men and two women). INTERVENTIONS: 62 patients were randomly allocated to a regular weekly aerobic training programme, three times a week for 12 months, and compared with 62 matched controls who did not receive any formal exercise training. A five year follow up questionnaire/interview was subsequently conducted on this population to determine selected vocational/lifestyle changes. RESULTS: Significant improvements in cardiorespiratory fitness (p < 0.01-0.001), psychological profiles (p < 0.05-0.001), and quality of life scores (p < 0.001) were recorded in the treatment population when compared with their matched controls. Although there were no significant differences in mortality, a larger percentage of the regular exercisers resumed full time employment and they returned to work earlier than the controls. Controls took lighter jobs, lost more time from work, and suffered more non-fatal reinfarctions (p < 0.05-0.01). CONCLUSIONS: Regularly supervised and prolonged aerobic exercise training improves cardiorespiratory fitness, psychological status, and quality of life. The trained population also had a reduction in morbidity following myocardial infarction, and significant improvement in vocational status over a five year follow up period.

Sustained improvement in left ventricular function after successful coronary angioplasty.

The short and long term effects of successful percutaneous transluminal coronary angioplasty on left ventricular function, at rest and on exercise were investigated in 49 patients. Thirty-four had had no previous infarction (group 1) and 15 had (group 2). Technetium-99m gated blood pool images were obtained at rest and during exercise before, six weeks after, and a mean of fifteen months after successful angioplasty. Before angioplasty the mean (SD) ejection fraction fell significantly on exercise in both groups from 58 (10)% to 53 (13)% in group 1 and from 48 (10)% to 40 (16)% in group 2. This change was paralleled by a worsening wall motion score (from 0.6 (0.4) to 1.6 (1.2) in group 1 and from 2.3 (1.9) to 3.3 (2.4) in group 2). Six weeks after the procedure there was little change in resting ejection fraction but it increased significantly on exercise (to 62 (11)% in group 1 and to 53 (13)% in group 2). There was a concomitant significant improvement in the exercise wall motion score (to 0.4 (0.6) in group 1 and to 1.8 (1.1) in group 2). This improvement in exercise ejection fraction and wall motion was maintained at later follow up with no significant deterioration in either variable and a clearly sustained improvement in ejection fraction (60 (10)% in group 1 and 51 (10)% in group 2) and wall motion score (0.2 (0.2) in group 1 and 1.3 (0.8) in group 2) compared with values before angioplasty. The initial improvement in left ventricular function on exercise after successful angioplasty was maintained for at least 9-24 months both in patients with previous myocardial infarction and in those without.

Osteomyelitis complicating Streptococcus milleri endocarditis.

A patient with osteomyelitis of the spine complicating bacterial endocarditis due to Streptococcus milleri is discussed. To our knowledge, this is the first time this organism has been associated with this complication.

Eligibility for thrombolytic therapy in acute myocardial infarction.

In a district general hospital's coronary care unit (CCU) 197 patients with chest pain were admitted over a 6-month period and in 131 an acute myocardial infarction (AMI) was confirmed. 67 (51%) were eligible for thrombolytic therapy, on criteria laid down for a trial of streptokinase. Criteria for thrombolysis were not fulfilled in 41 (31%) and 12 patients (9%) had contraindications. These results suggest that around half of all patients with AMI and about one-third of patients presenting with chest pain and admitted to a CCU would be suitable for thrombolytic therapy. These data do not support the view that such therapy may be applicable to only a small minority of patients with AMI.

Acquired pulmonary stenosis due to pleomorphic adenocarcinoma.

Acquired pulmonary stenosis was diagnosed in a 53 year old woman presenting with the unusual feature of an oral murmur. Mediastinotomy showed extensive malignant tissue surrounding the pulmonary artery, although a mediastinal mass was not evident on chest radiographs. Histological examination confirmed a pleomorphic adenocarcinoma, which has not previously been reported as causing acquired pulmonary stenosis.

Effect of GL enzyme (a highly purified form of hyaluronidase) on mortality after myocardial infarction.

The influence of intravenous GL enzyme (hyaluronidase) on the outcome of myocardial infarction was assessed in a controlled trial among 483 patients presenting within 6 h of the onset of symptoms. There was a consistent trend towards reduced mortality throughout the period of follow-up among GL enzyme treated patients. When the fate of all patients entering the trial was considered, irrespective of final diagnosis, the reduction in mortality at 6 months (27 of 240 GL enzyme patients, 45 of 243 placebo) was statistically significant (p = 0.025).

Reappraisal of lignocaine therapy in management of myocardial infarction.

The use of lignocaine in the prevention of ventricular fibrillation among patients admitted to a coronary care unit has been reviewed over the 12-year period 1967 to 1978 inclusive. The practice of suppressing warning ventricular ectopic activity has gradually been abandoned with the result that whereas in 1967 to 1968 33 per cent of all patients received lignocaine therapy, in 1972 to 1973 the number had fallen to 15 per cent, and in 1977 to 1978 to 4 per cent. The incidence of ventricular fibrillation was not significantly changed at 9.1, 7.7, and 7.8 per cent, respectively. Approximately 80 per cent of all patients suffering ventricular fibrillation within the coronary care unit were initially resuscitated and approximately 50 per cent survived hospital admission. Death was rarely a result of recurrent ventricular fibrillation and for the most part took the form of pump failure or late unexpected death. Experience suggests that the use of lignocaine to suppress ventricular ectopic activity observed in the first few hours of admission to hospital with acute myocardial infarction has no therapeutic value.