| 1. |
- Risenfors, M, et al.
(författare)
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Early thrombolytic therapy in suspected acute myocardial infarction : role of the electrocardiogram: results from the TEAHAT Study
- 1991
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Ingår i: Journal of Internal Medicine. - : Wiley-Blackwell Publishing Ltd.. - 0954-6820 .- 1365-2796. ; 734:suppl 1, s. 19-25
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Tidskriftsartikel (refereegranskat)abstract
- In a placebo-controlled trial in which rt-PA was administered to patients within 2 h and 45 min after the onset of symptoms indicative of acute myocardial infarction (AMI), 352 patients were randomized. Standard 12-lead electrocardiograms (ECGs) were recorded at inclusion and repeatedly during admission and at follow-up after 1 month and 1 year. In patients who presented with ST-segment elevation, the infarction rate was high (88%), whereas in patients without ST-elevation the infarction rate was low (21%), and infarct size, as assessed by serum enzyme activities, was small in this group. There were only minor differences between rt-PA- and placebo-treated patients with regard to ST-segment changes and Q-wave development, whereas the R-wave amplitude was higher after 1 month in patients who were given rt-PA. The infarction rate was not altered by rt-PA, but there was a shift towards a reduction in Q-wave infarction in patients who were treated with rt-PA. When a score system, as suggested by Palmeri et al., intended to reflect the ultimate infarct size, was applied, a significantly lower score was found in infarction patients who were treated with rt-PA as compared to placebo (3.95 +/- 0.35 vs. 2.95 +/- 0.29, P = 0.03), indicating limitation of infarct size. In summary, early treatment with rt-PA resulted in less frequent Q-wave infarction and a reduction in the electrocardiographically estimated infarct size.
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| 2. |
- Risenfors, M, et al.
(författare)
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Early treatment with thrombolysis and betablockade in suspected acute myocardial infarction : results from the TEAHAT Study
- 1991
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Ingår i: Journal of Internal Medicine. - : Wiley-Blackwell Publishing Ltd.. - 0954-6820 .- 1365-2796. ; 734:suppl 1, s. 35-42
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Tidskriftsartikel (refereegranskat)abstract
- Independent trials of early administration of beta-blockers and thrombolytic agents have shown beneficial effects on both short- and long-term prognoses in acute myocardial infarction (AMI). The effects of a combination of the two strategies have not been thoroughly documented. Three hundred and fifty-two patients, of less than 75 years of age, with chest pain indicative of AMI, and onset less than 2 h and 45 min before first examination, were randomized to treatment with rt-PA or placebo. All patients without contraindication were given intravenous metoprolol 15 mg acutely and then 200 mg orally daily. Treatment was started either at the prehospital stage or in hospital. Thirty-seven per cent of patients had contraindications to beta-blockade, the most frequent of which were heart rate less than 60 beats min-1 and hypotension. The remaining 63% were given intravenous beta-blockade. No side-effects of metoprolol, alone or in combination with rt-PA, were observed during the prehospital phase. Overall, toleration of the treatment was good. Reduction in enzymatically estimated infarct size by rt-PA was more pronounced in patients who were also treated with metoprolol (41%, P less than 0.001) than in those with contraindications to beta-blockade (15%, NS). Patients who were also treated with metoprolol also had a lower incidence of Q-wave infarctions, congestive heart failure and ventricular fibrillation than those who were not given intravenous beta-blockade. In conclusion, toleration of intravenous administration of rt-PA and metoprolol was good, and this was also the case in the prehospital phase.
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| 3. |
- Tägil, Kristina, et al.
(författare)
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A decision support system improves the interpretation of myocardial perfusion imaging.
- 2008
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 35:9, s. 1602-1607
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The aim of this study was to investigate the influence of a computer-based decision support system (DSS) on performance and inter-observer variability of interpretations regarding ischaemia and infarction in myocardial perfusion scintigraphy (MPS). METHODS: Seven physicians independently interpreted 97 MPS studies, first without and then with the advice of a DSS. Four physicians had long experience and three had limited experience in the interpretation of MPS. Each study was interpreted regarding myocardial ischaemia and infarction in five myocardial regions. The patients had undergone a gated MPS using a 2-day stress/gated rest (99m)Tc sestamibi protocol. The gold standard used was the interpretations made by one experienced nuclear medicine specialist on the basis of all available clinical and image information. RESULTS: The sensitivity for ischaemia of the seven readers increased from 81% without the DSS to 86% with the DSS (p = 0.01). The increase in sensitivity was higher for the three inexperienced physicians (9%) than for the four experienced physicians (2%). There was no significant change in specificity between the interpretations. The interpretations of ischaemia made with the advice of the DSS showed less inter-observer variability than those made without advice. CONCLUSION: This study shows that a DSS can improve performance and reduces the inter-observer variability of interpretations in myocardial perfusion imaging. Both experienced and, especially, inexperienced physicians can improve their interpretation with the advice from such a system.
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| 4. |
- Andersson, Bert, 1952, et al.
(författare)
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Heart rate dependency of cardiac performance in heart failure patients treated with metoprolol.
- 1999
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Ingår i: European heart journal. - 0195-668X. ; 20:8, s. 575-83
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Tidskriftsartikel (refereegranskat)abstract
- To investigate whether a low heart rate is necessary to maintain improvement in myocardial function after long-term treatment with a beta-blocker in patients with heart failure.Forty-eight patients with congestive heart failure were investigated: 30 patients with dilated cardiomyopathy participating in a placebo-controlled trial (15 on placebo, 15 on metoprolol), and 18 patients treated by metoprolol in an open protocol. Investigations of spontaneous heart rate and of matched paced heart rates were performed at baseline and after 3, 6 and 12 months of follow-up by radionuclide angiography. There were significant signs of improvement in systolic indices of the spontaneous heart rate in the metoprolol-treated group (peak ejection rate: 0.98 to 1.32 end-diastolic volume.s-1, P = 0.015) as compared to placebo (1.14 to 1.19 end-diastolic volume.s-1, not significant). Similar effects were observed during the matched paced heart rate (peak ejection rate: metoprolol 0.91 to 1.38 end-diastolic volume.s-1, P = 0.037; placebo 1.22 to 1.12 end-diastolic volume.s-1, not significant). No effects were observed in the early peak filling rate. Left ventricular volumes decreased during metoprolol treatment, both for the spontaneous heart rate and during matched pacing.These data imply that beta-blocker treatment improves the force-frequency relationship of myocardial performance. A lower heart rate is not necessary to maintain cardiac function on a short-term basis, once myocardial recovery has occurred.
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| 5. |
- Andersson, Bert, 1952, et al.
(författare)
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The link between acute haemodynamic adrenergic beta-blockade and long-term effects in patients with heart failure. A study on diastolic function, heart rate and myocardial metabolism following intravenous metoprolol.
- 1993
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Ingår i: European heart journal. - 0195-668X. ; 14:10, s. 1375-85
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Tidskriftsartikel (refereegranskat)abstract
- The present study was performed to find possible mechanisms linking the early effects of beta-blockade with the observed long-term effects in patients with heart failure. In 57 patients with heart failure, 13 +/- 3.1 mg of metoprolol was given intravenously. The patients were investigated by invasive haemodynamics (n = 34), including collection of myocardial metabolic data during atrial pacing stress (n = 16), by radionuclide angiography during physiological atrial pacing (n = 13), and by a bedside evaluation (n = 10). Diastolic function, measured by early peak filling rate, followed changes in heart rate, but was similar when heart rate was held constant by atrial pacing before and after beta-blockade. Following beta-blockade and slower heart rates, diastolic filling volumes were redistributed to late diastole. Metoprolol induced a parallel decrease in coronary sinus flow and myocardial oxygen consumption. Myocardial oxygen consumption following beta-blockade decreased both during spontaneous rhythm (25 +/- 15 to 16 +/- 8.8 ml min-1; P = 0.006), and during atrial pacing stress (30 +/- 13 to 23 +/- 11 ml.min-1; P = 0.004). Cardiac index decreased owing to reduction of heart rate (2.3 +/- 1.0 to 1.9 +/- 0.64 l.min-1.m2; P = 0.0003), while left ventricular filling pressure was unchanged. Ejection fraction and ventricular volumes were unaltered following atrial pacing or beta-blockade. There was a reflex increase in noradrenaline concentration after beta-blockade injection (0.96 +/- 0.66 to 1.20 +/- 0.91 nmol.l-1; P = 0.002), whereas myocardial noradrenaline overflow was unchanged. There was a trend towards an increase in myocardial lactate consumption after beta-blockade administration during atrial pacing stress. It is suggested that the surprisingly good tolerability seen after acute administration of beta-blockers to patients with severe heart failure may be explained by prolongation of the diastolic filling phase, which outweighs the negative inotropic effects. The reduced myocardial metabolic demand may allow the failing myocardium to recover and explain the excellent long-term effect on heart function following beta-blockade treatment.
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| 8. |
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| 9. |
- Tägil, Kristina, et al.
(författare)
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Use of neural networks to improve quality control of interpretations in myocardial perfusion imaging
- 2008
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Ingår i: International Journal of Cardiovascular Imaging. - : Springer Science and Business Media LLC. - 1875-8312 .- 1569-5794 .- 1573-0743. ; 24:8, s. 841-848
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Tidskriftsartikel (refereegranskat)abstract
- Background: The aim of this study was to explore the feasibility of using a technique based on artificial neural networks for quality assurance of image reporting. The networks were used to identify potentially suboptimal or erroneous interpretations of myocardial perfusion scintigrams (MPS). Methods: Reversible perfusion defects (ischaemia) in each of five myocardial regions, as interpreted by one experienced nuclear medicine physician during his daily routine of clinical reporting, were assessed by artificial neural networks in 316 consecutive patients undergoing stress/rest 99mTc-sestamibi myocardial perfusion scintigraphy. After a training process, the networks were used to select the 20 cases in each region that were more likely to have a false clinical interpretation. These cases, together with 20 control cases in which the networks detected no likelihood of false clinical interpretation, were presented in random order to a group of three experienced physicians for a consensus re-interpretation; no information regarding clinical or neural network interpretations was provided to the re-evaluation panel. Results: The clinical interpretation and the re-evaluation differed in 53 of the 200 cases. Forty-six of the 53 cases (87%) came from the group selected by the neural networks, and only seven (13%) were control cases (P < 0.001). The disagreements between clinical routine interpretation by an experienced nuclear medicine expert and artificial networks were related to small and mild perfusion defects and localization of defects. Conclusion: The results demonstrate that artificial neural networks can identify those myocardial perfusion scintigrams that may have suboptimal image interpretations. This is a potentially highly cost-effective technique, which could be of great value, both in daily practice as a clinical decision support tool and as a tool in quality assurance.
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| 10. |
- Ulmert, David, et al.
(författare)
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A novel automated platform for quantifying the extent of skeletal tumour involvement in prostate cancer patients using the bone scan index
- 2012
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Ingår i: European Urology. - : Elsevier BV. - 0302-2838 .- 1873-7560. ; 62:1, s. 78-84
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Tidskriftsartikel (refereegranskat)abstract
- Background: There is little consensus on a standard approach to analysing bone scan images. The Bone Scan Index (BSI) is predictive of survival in patients with progressive prostate cancer (PCa), but the popularity of this metric is hampered by the tedium of the manual calculation. Objective: Develop a fully automated method of quantifying the BSI and determining the clinical value of automated BSI measurements beyond conventional clinical and pathologic features. Design, setting, and participants: We conditioned a computer-assisted diagnosis system identifying metastatic lesions on a bone scan to automatically compute BSI measurements. A training group of 795 bone scans was used in the conditioning process. Independent validation of the method used bone scans obtained ≤3 mo from diagnosis of 384 PCa cases in two large population-based cohorts. An experienced analyser (blinded to case identity, prior BSI, and outcome) scored the BSI measurements twice. We measured prediction of outcome using pretreatment Gleason score, clinical stage, and prostate-specific antigen with models that also incorporated either manual or automated BSI measurements. Measurements: The agreement between methods was evaluated using Pearson's correlation coefficient. Discrimination between prognostic models was assessed using the concordance index (C-index). Results and limitations: Manual and automated BSI measurements were strongly correlated (ρ = 0.80), correlated more closely (ρ = 0.93) when excluding cases with BSI scores ≥10 (1.8%), and were independently associated with PCa death (p < 0.0001 for each) when added to the prediction model. Predictive accuracy of the base model (C-index: 0.768; 95% confidence interval [CI], 0.702-0.837) increased to 0.794 (95% CI, 0.727-0.860) by adding manual BSI scoring, and increased to 0.825 (95% CI, 0.754-0.881) by adding automated BSI scoring to the base model. Conclusions: Automated BSI scoring, with its 100% reproducibility, reduces turnaround time, eliminates operator-dependent subjectivity, and provides important clinical information comparable to that of manual BSI scoring. © 2012 European Association of Urology.
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