Richard Underwood

Myocardial infarction redefined - A consensus document of The Joint European Society of Cardiology/American College of Cardiology Committee f or the redefinition of myocardial infarction

This document was developed by a consensus conference initiated by Kristian Thygesen, MD, and Joseph S. Alpert, MD, after formal approval by Lars Rydén, MD, President of the European Society of Cardiology (ESC), and Arthur Garson, MD, President of the American College of Cardiology (ACC). All of the participants were selected for their expertise in the field they represented, with approximately one-half of the participants selected from each organization. Participants were instructed to review the scientific evidence in their area of expertise and to attend the consensus conference with prepared remarks. The first draft of the document was prepared during the consensus conference itself. Sources of funding appear in Appendix A. The recommendations made in this document represent the attitudes and opinions of the participants at the time of the conference, and these recommendations were revised subsequently. The conclusions reached will undoubtedly need to be revised as new scientific evidence becomes available. This document has been reviewed by members of the ESC Committee for Scientific and Clinical Initiatives and by members of the Board of the ESC who approved the document on April 15, 2000.*

A comparison of three radionuclide myocardial perfusion tracers in clinical practice: the ROBUST study.

Abstract. There are no large studies available to guide the selection of thallium (Tl), methoxyisobutylisonitrile (MIBI) or tetrofosmin (Tf) for myocardial perfusion imaging. Our objective was to compare the technical and clinical performance of the three in routine clinical practice. We randomised 2,560 patients to receive Tl, MIBI or Tf. A 1-day stress/rest protocol was used for MIBI and Tf. Tracer uptake was scored using a 17-segment model, quality and artefact scores were assigned, and ratios of heart (H), liver (L), subdiaphragmatic (S) and lung activity were measured. Mean quality scores (stress/rest) were Tl 2.13/2.16, MIBI 2.18/2.39, Tf 2.18/2.42 (P=ns stress and <0.00001 rest). For attenuation artefact, Tl>MIBI=Tf (P<0.05) and for low-count artefact Tl>MIBI>Tf (P<0.001). For H/S, Tl>MIBI=Tf, for H/L Tl>MIBI=Tf, and for H/lung Tl<MIBI=Tf. Stress defects in the patients with reversible or mixed perfusion defects were more severe for Tl than for the other tracers (mean summed score out of 68: Tl 52.3, MIBI 55.7, Tf 54.4, P<0.01), but mean rest scores were more similar (Tl 58.7, MIBI 60.7, Tf 59.4, P=0.02). In the subset of 137 patients undergoing diagnostic perfusion studies without prior infarction, angiography or revascularisation, overall sensitivity for the detection of coronary disease defined by subsequent angiography was 91% with a specificity of 87%. There were no significant differences between the tracers with regard to sensitivity and specificity. In conclusion: There are technical differences between the tracers. Overall image quality score is superior using technetium, with less low-count artefact and less attenuation. Stress defect depth and extent are slightly greater using thallium, with no difference between MIBI and tetrofosmin. All three tracers perform well in clinical terms, with high sensitivity and specificity for angiographic stenosis and no differences in accuracy between the tracers.

Clinical value, cost-effectiveness, and safety of myocardial perfusion scintigraphy: a position statement

Mortality rates due to coronary artery disease (CAD) have declined in recent years as result of improved prevention, diagnosis, and management. Nonetheless, CAD remains the leading cause of death worldwide with most casualties expected to occur in developing nations. Myocardial perfusion scintigraphy (MPS) provides a highly cost-effective tool for the early detection of obstructive CAD in symptomatic individuals and contributes substantially to stratification of patients according to their risk of cardiac death or nonfatal myocardial infarction. MPS also provides valuable information that assists clinical decision-making with regard to medical treatment and intervention. A large body of evidence supports the current applications of MPS, which has become integral to several guidelines for clinical practice.

Application of flow measurements by magnetic resonance velocity mapping to congenital heart disease

Abstract Measurement of flow in the systemic and pulmonary circulations is one of the main reasons for performing cardiac catheterization in patients with congenital heart disease. We have previously reported a magnetic resonance method of flow measurement that involves the acquisition of velocity maps 1,2 using a field-echo sequence with even echo rephasing (FEER). 3,4 It depends on the fact that a magnetic resonance signal has both amplitude and phase and that phase can be encoded to give a measure of flow velocity. Stationary tissues have zero phase and are shown as mid-gray, but flowing blood has a phase shift, which is proportional to its velocity in a defined direction and is displayed as a darker or lighter shade.

Comparison of magnetic resonance imaging with echocardiography and radionuclide angiography in assessing cardiac function and anatomy following mustard's operation for transposition of the great arteries

The Mustard operation in infancy and childhood has successfully palliated many patients with transposition of the great arteries who have now survived to adulthood. Right ventricular dysfunction and tricuspid regurgitation are important determinants of late morbidity and mortality. The value of noninvasive magnetic resonance imaging (MRI) in the assessment of cardiac function and anatomy 9 to 20 years after this procedure has been investigated, and compared with findings on echocardiography, radionuclide ventriculography and angiography in 17 adult patients. Ejection fractions measured by MRI were higher compared with radionuclide ventriculography. The correlation for the left ventricle was closer (r = 0.75) than for the right ventricle (r = 0.49). Tricuspid regurgitation was assessed by Doppler echocardiography and by MRI using the right/left ventricular stroke volume ratio. The mean stroke volume ratio in those with Doppler evidence of tricuspid regurgitation was 1.6:1 compared to 1.1:1 in those without, and this difference reached significance (p less than 0.01). The anatomy of the great arteries was clearly visible in all patients. Five patients had a residual ventricular septal defect which, with the exception of 1 small defect, was easily visualized. The intraatrial baffle was best seen in transverse slices, and the systemic venous connection showed as a relatively narrow channel lying in the posterior part of the cavity. In general, baffle anatomy was easier to assess on 2-dimensional echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison between cine magnetic resonance velocity mapping and first-pass radionuclide angiocardiography for quantitating intracardiac shunts

Abstract We conclude that first-pass radionuclide angio-cardiography has limited value when measuring Qp/Qs in our group of patients, and that magnetic resonance imaging with velocity mapping is an excellent alternative technique that should be considered, particularly in patients with complex congenital disease and right-to-left shunt, or when poor bolus quality is anticipated.

Evaluation of Fontan's operation by magnetic resonance imaging

Abstract Fontan-type procedures for tricuspid atresia 1–3 and the modifications used for other complex cyanotic cardiac malformations 4,5 should be judged by the complications and long-term state of patients. 6 The most important complication is insidious obstruction. Early recognition of this is vital since it can lead to arrhythmias and loss of atrial and ventricular function. At catheterization attention must be paid to small gradients as low as 2 or 3 mm Hg. A reliable noninvasive method for assessing the atriopulmonary connection as well as the cardiac function applicable to outpatients is necessary for proper management. Magnetic resonance imaging (MRI) has been used as a noninvasive method of assessing congenital heart disease, both pre- and postoperatively. 7–10 This study assesses its value for demonstrating the anatomy of the atriopulmonary connection and recognizing obstruction compared to 2-dimensional echocardiography and the findings at catheterization and operation.

A comparison of resting images from two myocardial perfusion tracers

We have compared stress-redistribution and delayed rest thallium-201 with rest technetium-99m methoxyisobutylisonitrile (MIBI) tomograms in order to compare the tracers for the assessment of myocardial viability and to validate a rapid protocol combining the two tracers. We studied 30 consecutive patients with known or suspected coronary artery disease [group 1: 16 with normal left ventricular function, mean left ventricular ejection fraction (LVEF) 55%, SD 6%; group 2: 14 with abnormal function, mean LVEF 28%, SD 8%].201Tl was injected during infusion of adenosine followed by acquisition of conventional stress and redistribution tomograms. On a separate day,201Tl was injected at rest with imaging 4 h later.99mTc-MIBI was then given at rest and imaging was performed. Three images were compared: redistribution201Tl, rest201Tl, and rest99mTc-MIBI. Tracer activity was classified visually and quantitatively in nine segments and segments with>50% activity were defined as containing clinically significant viable myocardium. Mean (±SD) global tracer uptake as a percentage of maximum was similar in group 1 (rest201Tl 69%±12%, redistribution201Tl 69%±15%, rest99mTc-MIBI 70%±13%, ANOVAP>0.05), but in group 2 mean tracer uptake was significantly greater in the rest201Tl images (59%±16%) than in redistribution201Tl images (53%±17%) or rest99mTc-MIBI images (53%±19%) (ANOVAP=0.02). Overall agreement for regional uptake score was excellent (κ from 0.79 to 0.84), although there were a significant number of segments with less uptake shown by redistribution201Tl and by rest99mTc-MIBI than by rest201Tl in group 2 (P<0.001). The number of segments with significant viable myocardium in group 1 was very similar between the three images (P>0.05) but in group 2 rest201Tl identified significantly more segments as viable than the other images (McNemarP<0.001). Thus201Tl and99mTc-MIBI provide similar information in patients without prior infarction and with normal left ventricular function (group 1), and a rapid protocol with stress201Tl injection and imaging followed immediately by rest99mTc-MIBI injection and imaging is feasible. In patients with abnormal left ventricular function and prior infarction (group 2),99mTc-MIBI may underestimate the extent of clinically significant viable myocardium.

Procedure guidelines for radionuclide myocardial perfusion imaging with single-photon emission computed tomography.

Myocardial perfusion scintigraphy uses an intravenously administered radiopharmaceutical to image myocardial viability and perfusion during stimulation of the perfusion system and at rest. The images are acquired using a gamma camera, and tomographic imaging is preferred over planar imaging because of the three-dimensional nature of the images and their superior contrast resolution. Comparison of myocardial distribution of the radiopharmaceutical after stress and at rest provides information on myocardial viability, inducible perfusion abnormalities and, when ECG-gated imaging is used, global and regional myocardial function.

Assessment of cardiac risk before peripheral vascular surgery: a comparison of myocardial perfusion imaging and long axis echocardiography at rest.

OBJECTIVE To compare resting long axis echocardiography with adenosine thallium-201 emission tomography in detecting myocardial ischaemic abnormalities and surgical related risk in patients before peripheral vascular surgery. DESIGN A prospective and blinded pre-operative examination of resting left ventricular minor and long axes and myocardial perfusion during adenosine vasodilation using thallium-201 emission tomography. SETTING A tertiary referral centre for cardiac and vascular disease equipped with invasive, non-invasive and surgical facilities. SUBJECTS 65 patients (40 male) with significant peripheral vascular disease, mean age 63+/-10 (S.D.) years, and 21 normal subjects of similar age. RESULTS Thallium-201 myocardial perfusion tomography was abnormal in 50/65 patients; 27 had fixed, 23 reversible abnormalities (19 of whom had both). Long axis was considered abnormal if one or more of two systolic long axis disturbances, reduced extent of total excursion <1 cm at any of the three (left, septal and posterior left ventricular) sites or prolonged shortening >1 mm after A2, and two diastolic abnormalities, delayed onset of lengthening >80 ms after A2 or reduced peak lengthening velocity <4.5 cm/s, was present. Long axis score (maximum 12) was based on the presence or absence of these four disturbances at each of the three sites. Myocardial perfusion imaging with thallium-201 classified the patients into three different groups according to their liability to low, moderate or high surgical risk (summed stress perfusion score of 36). Thirteen of 50 patients were identified as subjects at high surgical risk, with a perfusion score of 22/36 and below. Twelve of these demonstrated significantly greater impairment of systolic and diastolic long axis function, compared to those at low surgical risk, with a total long axis echo score of 6/12 or more. Seventeen of 18 patients identified as being at low surgical risk, with a perfusion score of 32/36 and above, had total long axis score of less than 6/12. The remaining 19 moderate risk patients had a wide range of long axis scores. In the 65 patients studied there were two post-operative deaths, one post-discharge death due to cerebrovascular accident, and one due to renal failure. CONCLUSION The combination of both systolic and diastolic long axis disturbances in patients with peripheral vascular disease can be used to predict the thallium assessment of surgical risk. Long axis echocardiography may thus have value as a screening test before non-cardiac surgery as well as providing a means of monitoring myocardial perfusion.