Recent developments in non-invasive cardiology
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《英国医生杂志》
1 Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London SW3 6NP
Correspondence to: S K Prasad s.prasad@rbh.nthames.nhs.uk
Introduction
Cardiovascular magnetic resonance imaging has improved the detection of heart disease. Accurate diagnosis provides the basis of treatment options and of monitoring response to treatment. It also gives important prognostic information that can be difficult to glean from the history and examination alone. Conventional procedures such as echocardiography often produce suboptimal images due to poor echo windows with limited spatial resolution. In particular, the apex of the left ventricle is difficult to visualise, resulting in missed diagnoses such as apical hypertrophic cardiomyopathy.1 X ray angiography is invasive and associated with morbidity and mortality as well as exposure to ionising radiation. Cardiovascular magnetic resonance yields high resolution, high contrast images by mapping the radio signals absorbed and emitted by hydrogen nuclei in a powerful magnetic field. No x rays are involved. The contrast agent gadolinium is sometimes used to increase the signal. Gadolinium is safe, even in patients with severe renal failure. Scans can be oriented in any plane of the body and are not limited by acoustic windows. Because of its three dimensional nature, magnetic resonance imaging has become the ideal method for measuring ventricular mass and volume.2 Some patients are not suitable for the procedure, such as those with cardiac pacemakers or defibrillators. Scanning should also be avoided in patients with metallic fragments near a vital structure, such as the retina, or with brain aneurysm clips. Patients with claustrophobia may be difficult to scan, although small doses of benzodiazepine can help. Pregnant women can be scanned, although preferably not in the first trimester.
Recent advances
Cardiovascular magnetic resonance imaging is the newest technique for non-invasive cardiology
It assesses cardiac function, mass, and volume and can detect myocardial infarction and fibrosis
Computed tomography is used to quantify coronary calcium, high scores being related to increased risk, but its use remains controversial
Myocardial perfusion scintigraphy single photon emission computed tomography is cost effective in investigating patients with suspected coronary disease
Ambulatory blood pressure monitoring is now a valuable technique for guiding practice in hypertension
The level of B natriuretic peptide increases with ventricular dysfunction, thus providing prognostic information
Cardiovascular magnetic resonance imaging has a rapidly increasing role in cardiology (box 1) and is routinely used to assess anatomy, cardiovascular function, and blood flow. It is also valuable in angiography, where it has supplanted invasive techniques other than for assessing the coronary circulation.
Infarction and viability
Gadolinium accumulates in myocardial scar and fibrotic tissue and provides high resolution images, something that has never before been possible in vivo. Myocardial infarction can be detected with exquisite sensitivity, which has the potential to improve the management of chest pain syndromes (fig 1) and to predict functional improvement after revascularisation.3 Emerging practical applications include adjudication when other techniques give equivocal results (for example, borderline abnormal results on electrocardiography, minor motion wall abnormalities on echocardiography), and the assessment of myocardial viability.4 5 These findings correlate well with positron emission tomography6 but without the drawbacks of poorer spatial resolution, cost, and radiation. Such studies should be considered when there is uncertainty about previous infarction or about the benefits of revascularisation.
Fig 1 Gadolinium enhanced images of patient with lateral wall myocardial infarction. Four chamber view of heart (A), with bright signal in lateral wall of left ventricle (LV). Signal results from gadolinium late enhancement as result of accumulation of contrast agent in scar tissue. (B) Corresponding short axis cut through left ventricle
Coronary angiography
The role of magnetic resonance imaging in the detection of coronary disease and characterisation of atheroma is still under investigation, but shows promise. Around 72% of patients have been accurately diagnosed as having any coronary artery disease and 87% as having left main vessel or three vessel disease.7 Uniquely, cardiovascular magnetic resonance can be used to examine the composition and size of carotid and coronary plaques and has the potential to identify plaques vulnerable to rupture.8 Cardiovascular magnetic resonance is now used to identify the course of anomalous coronary arteries, which are associated with sudden death, and for this application the technique is regarded as the ideal.9 It is not recommended for routine detection of coronary artery disease as its spatial resolution is inferior to that of coronary angiography.
Myocardial perfusion imaging
Perfusion cardiovascular magnetic resonance imaging is being developed. This involves fast imaging of the myocardium during the passage of a bolus of gadolinium. The procedure takes less than 20 minutes, involves no ionising radiation, and has much higher resolution than conventional techniques such as scintigraphy single photon emission computed tomography and positron emission tomography. In a study of patients with angina but with normal coronary arteries (syndrome X), subendocardial perfusion gave abnormal results with cardiovascular magnetic resonance imaging but not with scintigraphy single photon emission.10 Perfusion imaging may lead to better diagnosis and treatment of patients with normal coronary angiograms (10-20% of coronary angiograms). Early work on perfusion cardiovascular magnetic resonance imaging in coronary disease seems promising.11
Box 1: Current clinical applications of cardiovascular magnetic resonance imaging
General—measurement of cardiac volume and function; if echocardiography is unsatisfactory
Great vessels—accurate sizing; detection of dissection, coarctation, stenosis; anomalous vessels
Congenital heart disease—check for concordance of atrioventricular or ventriculoarterial connections; check for great vessels connections; assessment of conduits; assessment of complex anatomy
Ischaemic heart disease—detection of regional wall motion abnormalities or infarction; assessment of viability
Cardiomyopathy—identification of hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy; detection of fibrosis or scarring; risk stratification; quantification of iron overload in thalassemia
Left ventricular mass—accurate assessment in hypertension; assessment of response to therapy
Valvular disease—quantification of regurgitation
Pericardium—assessment of thickening
Cardiac masses—characterisation of tissue; assessment of extent of tumour
X ray computed tomography in ischaemic heart disease
A difficult challenge in clinical practice is evaluating the differential importance of coronary lesions in patients with multivessel disease. Single photon emission computed tomography (SPECT) is the current standard for assessing the haemodynamic effects of coronary stenoses. It relies on the difference in distribution of a radioactive tracer, such as thallium, at rest and after stress. In patients with myocardial ischaemia, uptake of tracer is reduced after stress and improves at rest. Single photon emission computed tomography is more specific and sensitive in the diagnosis of ischaemia than is exercise electrocardiography, and the extent and severity of the abnormality is strongly predictive of future cardiac events. This information can be used to direct revascularisation strategies such as angioplasty or bypass surgery. Single photon emission computed tomography is also useful in the non-invasive evaluation of patients, particularly women, with equivocal or suboptimal exercise test results.
Major advances have been recently implemented with single photon emission computed tomography. Firstly, image gating has allowed the simultaneous assessment of perfusion and wall motion by linking cardiac motion to each point in the cardiac cycle on the electrocardiogram. This improves specificity in areas affected by attenuation artefacts, while providing information on ventricular volumes and function.17 Secondly, cost effectiveness is now established, and strategies that include the technique early in the work-up of patients with suspected coronary disease have been shown to be beneficial in terms of clinical outcome and cost.18 Thirdly, recent work has established the technique's benefit in avoiding unnecessary admissions to hospital in patients with acute coronary syndromes,19 and the acceptance that normal or near normal perfusion results usually obviate the need for invasive coronary angiography because of low hard annual event rates of < 1% (fig 3). In contrast, patients with abnormal scans have a 12-fold greater annual event rate (7.4%).20
Fig 3 Nuclear perfusion scan showing noticeably impaired perfusion in all territories except for basal septum. Results also offer quantitative analysis of left ventricular volume and estimation of ejection fraction
B natriuretic peptide in heart failure
Moon JC, Fisher NG, McKenna WJ, Pennell DJ. Detection of apical hypertrophic cardiomyopathy by cardiovascular magnetic resonance in patients with non-diagnostic echocardiography. Heart 2004;90: 645-9.
Bellenger NG, Burgess MI, Ray SG, Lahiri A, Coats AJ, Cleland JG, et al. Comparison of left ventricular ejection fraction and volumes in heart failure by echocardiography, radionuclide ventriculography and cardiovascular magnetic resonance; are they interchangeable? Eur Heart J 2000;21: 1387-96.
Beek AM, Kühl HP, Bondarenko O, Twisk JW, Hofman MB, van Dockum WG, et al. Delayed contrast-enhanced magnetic resonance imaging for the prediction of regional functional improvement after acute myocardial infarction. J Am Coll Cardiol 2003;42: 895-901.
Kim RJ, Wu E, Rafael A, Chen EL, Parker MA, Simonetti O, et al. The use of contrast-enhanced magnetic resonance imaging to identify reversible myocardial dysfunction. N Engl J Med 2000;343: 1445-53.
Gerber BL, Garot J, Bluemke DA, Wu KC, Lima JA. Accuracy of contrast-enhanced magnetic resonance imaging in predicting improvement of regional myocardial function in patients after acute myocardial infarction. Circulation 2002;106: 1083-9.
Klein C, Nekolla SG, Bengel FM, Momose M, Sammer A, Haas F, et al. Assessment of myocardial viability with contrast-enhanced magnetic resonance imaging: comparison with positron emission tomography. Circulation 2002;105: 162-7.
Kim WY, Danias PG, Stuber M, Flamm SD, Plein S, Nagel E, et al. Coronary magnetic resonance angiography for the detection of coronary stenoses. N Engl J Med 2001;345: 1863-9.
Yuan C, Zhang SX, Polissar NL, Echelard D, Ortiz G, Ellington E, et al. Identification of fibrous cap rupture with magnetic resonance imaging is highly associated with recent transient ischemic attack or stroke. Circulation 2002;105; 181-5.
Taylor AM, Thorne SA, Rubens MB, Jhooti P, Keegan J, Gatehouse PD, et al. Coronary artery imaging in grown-up congenital heart disease: complementary role of MR and x-ray coronary angiography. Circulation 2000;101: 1670-8.
Panting JR, Gatehouse PD, Yang GZ, Grothues F, Firmin DN, Collins P, et al. Abnormal subendocardial perfusion in cardiac syndrome-X detected by cardiovascular magnetic resonance imaging. N Engl J Med 2002;346: 1948-53.
Nagel E, Klein C, Paetsch I, Hettwer S, Schnackenburg B, Wegscheider K, et al. Magnetic resonance perfusion measurements for the noninvasive detection of coronary artery disease. Circulation 2003;108(4): 432-7.
Rich S, McLaughlin VV. Detection of subclinical cardiovascular disease: the emerging role of electron beam computed tomography. Prev Med 2002;34: 1-10.
Rumberger JA, Simons DB, Fitzpatrick LA, Sheedy PF, Schwartz RS. Coronary artery calcium area by electron-beam computed tomography and coronary atherosclerotic plaque area. A histopathologic correlative study. Circulation 1995;92: 2157-62.
Raggi P, Callister TQ, Cooil B, He ZX, Lippolis NJ, Russo DJ, et al. Identification of patients at increased risk of first unheralded acute myocardial infarction by electron-beam computed tomography. Circulation 2000;101: 850-5.
Detrano RC, Wong ND, Doherty TM, Shavelle RM, Tang W, Ginzton LE, et al. Coronary calcium does not accurately predict near term future coronary events in high risk adults. Circulation 1999;99: 2633-8.
O'Rourke RA, Brundage BH, Froelicher VF, Greenland P, Grundy SM, Hachamovitch R, et al. American College of Cardiology/American Heart Association expert consensus document on electron-beam computed tomography for the diagnosis and prognosis of coronary artery disease. Circulation 2000;102: 126-40.
Taillefer R, DePuey EG, Udelson JE, Beller GA, Benjamin C, Gagnon A. Comparison between the end-diastolic images and the summed images of gated 99mTc-sestamibi SPECT perfusion study in detection of coronary artery disease in women. J Nucl Cardiol 1999;6: 169-76.
Underwood SR, Godman B, Salyani S, Ogle JR, Ell PJ. Economics of myocardial perfusion imaging in Europe—the EMPIRE study. Eur Heart J 1999;20: 157-66.
Klocke FJ, Baird MG, Lorell BH, Bateman TM, Messer JV, Berman DS, et al. ACC/AHA/ASNC guidelines for the clinical use of cardiac radionuclide imaging—executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/ASNC Committee to Revise the 1995 Guidelines for the Clinical Use of Cardiac Radionuclide Imaging). J Am Coll Cardiol 2003;42(7): 1318-33.
Shaw LJ, Iskandrian AE, Hachamovitch R, Germano G, Lewin HC, Bateman TM, et al. Evidence-based risk assessment in noninvasive imaging. J Nucl Med 2001;42: 1424-36.
Maisel A. B type natriuretic peptide levels: diagnostic and prognostic in congestive heart failure. Circulation 2002;105: 2328.
Krishnaswamy P, Lubien E, Clopton P, Koon J, Kazanegra R, Wanner E, et al. Utility of B-natriuretic peptide levels in identifying patients with left ventricular systolic or diastolic dysfunction. Am J Med 2001;111: 274-9.
Chen HH, Burnett JC. Natriuretic peptides in the pathophysiology of congestive heart failure. Curr Cardiol Rep 2000;2: 198-205.
Harrison A, Morrison LK, Krishnaswamy P. B-type natriuretic peptide predicts future cardiac events in patients presenting to the emergency department with dyspnea. Ann Emerg Med 2002;39: 131-8.
Troughton RW, Frampton CM, Yandle TG, Espiner EA, Nicholls MG, Richards AM. Treatment of heart failure guided by plasma aminoterminal brain natriuretic peptide (N-BNP) concentrations. Lancet 2000;355: 1126-30.
Richards AM, Doughty R, Nicholls MG, MacMahon S, Sharpe N, Murphy J, et al. Plasma N-terminal pro-brain natriuretic peptide and adrenomedullin: prognostic utility and prediction of benefit from carvedilol in chronic ischemic left ventricular dysfunction. Australia-New Zealand Heart Failure Group. J Am Coll Cardiol 2001;37: 1781-7.
Maisel AS, Krishnaswamy P, Nowak RM, McCord J, Hollander JE, Duc P, et al. Rapid measurement of B-type natriuretic peptide in the emergency diagnosis of heart failure. N Engl J Med 2002;347: 161-7.
Hobbs FDR, Davis RC, Roalfe AK, Davies MK, Kenkre JE. Reliability of N-terminal pro-brain natriuretic peptide assay in diagnosis of heart failure: cohort study in representative and high risk community populations. BMJ 2002;324: 1498-500.
Heidenreich PA, Gubens MA, Fonarow GC, Konstam MA, Stevenson LW, Shekelle PG. Cost-effectiveness of screening with B-type natriuretic peptide to identify patients with reduced left ventricular ejection fraction. J Am Coll Cardiol 2004;43: 1019-26.(Sanjay K Prasad, consulta)
Correspondence to: S K Prasad s.prasad@rbh.nthames.nhs.uk
Introduction
Cardiovascular magnetic resonance imaging has improved the detection of heart disease. Accurate diagnosis provides the basis of treatment options and of monitoring response to treatment. It also gives important prognostic information that can be difficult to glean from the history and examination alone. Conventional procedures such as echocardiography often produce suboptimal images due to poor echo windows with limited spatial resolution. In particular, the apex of the left ventricle is difficult to visualise, resulting in missed diagnoses such as apical hypertrophic cardiomyopathy.1 X ray angiography is invasive and associated with morbidity and mortality as well as exposure to ionising radiation. Cardiovascular magnetic resonance yields high resolution, high contrast images by mapping the radio signals absorbed and emitted by hydrogen nuclei in a powerful magnetic field. No x rays are involved. The contrast agent gadolinium is sometimes used to increase the signal. Gadolinium is safe, even in patients with severe renal failure. Scans can be oriented in any plane of the body and are not limited by acoustic windows. Because of its three dimensional nature, magnetic resonance imaging has become the ideal method for measuring ventricular mass and volume.2 Some patients are not suitable for the procedure, such as those with cardiac pacemakers or defibrillators. Scanning should also be avoided in patients with metallic fragments near a vital structure, such as the retina, or with brain aneurysm clips. Patients with claustrophobia may be difficult to scan, although small doses of benzodiazepine can help. Pregnant women can be scanned, although preferably not in the first trimester.
Recent advances
Cardiovascular magnetic resonance imaging is the newest technique for non-invasive cardiology
It assesses cardiac function, mass, and volume and can detect myocardial infarction and fibrosis
Computed tomography is used to quantify coronary calcium, high scores being related to increased risk, but its use remains controversial
Myocardial perfusion scintigraphy single photon emission computed tomography is cost effective in investigating patients with suspected coronary disease
Ambulatory blood pressure monitoring is now a valuable technique for guiding practice in hypertension
The level of B natriuretic peptide increases with ventricular dysfunction, thus providing prognostic information
Cardiovascular magnetic resonance imaging has a rapidly increasing role in cardiology (box 1) and is routinely used to assess anatomy, cardiovascular function, and blood flow. It is also valuable in angiography, where it has supplanted invasive techniques other than for assessing the coronary circulation.
Infarction and viability
Gadolinium accumulates in myocardial scar and fibrotic tissue and provides high resolution images, something that has never before been possible in vivo. Myocardial infarction can be detected with exquisite sensitivity, which has the potential to improve the management of chest pain syndromes (fig 1) and to predict functional improvement after revascularisation.3 Emerging practical applications include adjudication when other techniques give equivocal results (for example, borderline abnormal results on electrocardiography, minor motion wall abnormalities on echocardiography), and the assessment of myocardial viability.4 5 These findings correlate well with positron emission tomography6 but without the drawbacks of poorer spatial resolution, cost, and radiation. Such studies should be considered when there is uncertainty about previous infarction or about the benefits of revascularisation.
Fig 1 Gadolinium enhanced images of patient with lateral wall myocardial infarction. Four chamber view of heart (A), with bright signal in lateral wall of left ventricle (LV). Signal results from gadolinium late enhancement as result of accumulation of contrast agent in scar tissue. (B) Corresponding short axis cut through left ventricle
Coronary angiography
The role of magnetic resonance imaging in the detection of coronary disease and characterisation of atheroma is still under investigation, but shows promise. Around 72% of patients have been accurately diagnosed as having any coronary artery disease and 87% as having left main vessel or three vessel disease.7 Uniquely, cardiovascular magnetic resonance can be used to examine the composition and size of carotid and coronary plaques and has the potential to identify plaques vulnerable to rupture.8 Cardiovascular magnetic resonance is now used to identify the course of anomalous coronary arteries, which are associated with sudden death, and for this application the technique is regarded as the ideal.9 It is not recommended for routine detection of coronary artery disease as its spatial resolution is inferior to that of coronary angiography.
Myocardial perfusion imaging
Perfusion cardiovascular magnetic resonance imaging is being developed. This involves fast imaging of the myocardium during the passage of a bolus of gadolinium. The procedure takes less than 20 minutes, involves no ionising radiation, and has much higher resolution than conventional techniques such as scintigraphy single photon emission computed tomography and positron emission tomography. In a study of patients with angina but with normal coronary arteries (syndrome X), subendocardial perfusion gave abnormal results with cardiovascular magnetic resonance imaging but not with scintigraphy single photon emission.10 Perfusion imaging may lead to better diagnosis and treatment of patients with normal coronary angiograms (10-20% of coronary angiograms). Early work on perfusion cardiovascular magnetic resonance imaging in coronary disease seems promising.11
Box 1: Current clinical applications of cardiovascular magnetic resonance imaging
General—measurement of cardiac volume and function; if echocardiography is unsatisfactory
Great vessels—accurate sizing; detection of dissection, coarctation, stenosis; anomalous vessels
Congenital heart disease—check for concordance of atrioventricular or ventriculoarterial connections; check for great vessels connections; assessment of conduits; assessment of complex anatomy
Ischaemic heart disease—detection of regional wall motion abnormalities or infarction; assessment of viability
Cardiomyopathy—identification of hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy; detection of fibrosis or scarring; risk stratification; quantification of iron overload in thalassemia
Left ventricular mass—accurate assessment in hypertension; assessment of response to therapy
Valvular disease—quantification of regurgitation
Pericardium—assessment of thickening
Cardiac masses—characterisation of tissue; assessment of extent of tumour
X ray computed tomography in ischaemic heart disease
A difficult challenge in clinical practice is evaluating the differential importance of coronary lesions in patients with multivessel disease. Single photon emission computed tomography (SPECT) is the current standard for assessing the haemodynamic effects of coronary stenoses. It relies on the difference in distribution of a radioactive tracer, such as thallium, at rest and after stress. In patients with myocardial ischaemia, uptake of tracer is reduced after stress and improves at rest. Single photon emission computed tomography is more specific and sensitive in the diagnosis of ischaemia than is exercise electrocardiography, and the extent and severity of the abnormality is strongly predictive of future cardiac events. This information can be used to direct revascularisation strategies such as angioplasty or bypass surgery. Single photon emission computed tomography is also useful in the non-invasive evaluation of patients, particularly women, with equivocal or suboptimal exercise test results.
Major advances have been recently implemented with single photon emission computed tomography. Firstly, image gating has allowed the simultaneous assessment of perfusion and wall motion by linking cardiac motion to each point in the cardiac cycle on the electrocardiogram. This improves specificity in areas affected by attenuation artefacts, while providing information on ventricular volumes and function.17 Secondly, cost effectiveness is now established, and strategies that include the technique early in the work-up of patients with suspected coronary disease have been shown to be beneficial in terms of clinical outcome and cost.18 Thirdly, recent work has established the technique's benefit in avoiding unnecessary admissions to hospital in patients with acute coronary syndromes,19 and the acceptance that normal or near normal perfusion results usually obviate the need for invasive coronary angiography because of low hard annual event rates of < 1% (fig 3). In contrast, patients with abnormal scans have a 12-fold greater annual event rate (7.4%).20
Fig 3 Nuclear perfusion scan showing noticeably impaired perfusion in all territories except for basal septum. Results also offer quantitative analysis of left ventricular volume and estimation of ejection fraction
B natriuretic peptide in heart failure
Moon JC, Fisher NG, McKenna WJ, Pennell DJ. Detection of apical hypertrophic cardiomyopathy by cardiovascular magnetic resonance in patients with non-diagnostic echocardiography. Heart 2004;90: 645-9.
Bellenger NG, Burgess MI, Ray SG, Lahiri A, Coats AJ, Cleland JG, et al. Comparison of left ventricular ejection fraction and volumes in heart failure by echocardiography, radionuclide ventriculography and cardiovascular magnetic resonance; are they interchangeable? Eur Heart J 2000;21: 1387-96.
Beek AM, Kühl HP, Bondarenko O, Twisk JW, Hofman MB, van Dockum WG, et al. Delayed contrast-enhanced magnetic resonance imaging for the prediction of regional functional improvement after acute myocardial infarction. J Am Coll Cardiol 2003;42: 895-901.
Kim RJ, Wu E, Rafael A, Chen EL, Parker MA, Simonetti O, et al. The use of contrast-enhanced magnetic resonance imaging to identify reversible myocardial dysfunction. N Engl J Med 2000;343: 1445-53.
Gerber BL, Garot J, Bluemke DA, Wu KC, Lima JA. Accuracy of contrast-enhanced magnetic resonance imaging in predicting improvement of regional myocardial function in patients after acute myocardial infarction. Circulation 2002;106: 1083-9.
Klein C, Nekolla SG, Bengel FM, Momose M, Sammer A, Haas F, et al. Assessment of myocardial viability with contrast-enhanced magnetic resonance imaging: comparison with positron emission tomography. Circulation 2002;105: 162-7.
Kim WY, Danias PG, Stuber M, Flamm SD, Plein S, Nagel E, et al. Coronary magnetic resonance angiography for the detection of coronary stenoses. N Engl J Med 2001;345: 1863-9.
Yuan C, Zhang SX, Polissar NL, Echelard D, Ortiz G, Ellington E, et al. Identification of fibrous cap rupture with magnetic resonance imaging is highly associated with recent transient ischemic attack or stroke. Circulation 2002;105; 181-5.
Taylor AM, Thorne SA, Rubens MB, Jhooti P, Keegan J, Gatehouse PD, et al. Coronary artery imaging in grown-up congenital heart disease: complementary role of MR and x-ray coronary angiography. Circulation 2000;101: 1670-8.
Panting JR, Gatehouse PD, Yang GZ, Grothues F, Firmin DN, Collins P, et al. Abnormal subendocardial perfusion in cardiac syndrome-X detected by cardiovascular magnetic resonance imaging. N Engl J Med 2002;346: 1948-53.
Nagel E, Klein C, Paetsch I, Hettwer S, Schnackenburg B, Wegscheider K, et al. Magnetic resonance perfusion measurements for the noninvasive detection of coronary artery disease. Circulation 2003;108(4): 432-7.
Rich S, McLaughlin VV. Detection of subclinical cardiovascular disease: the emerging role of electron beam computed tomography. Prev Med 2002;34: 1-10.
Rumberger JA, Simons DB, Fitzpatrick LA, Sheedy PF, Schwartz RS. Coronary artery calcium area by electron-beam computed tomography and coronary atherosclerotic plaque area. A histopathologic correlative study. Circulation 1995;92: 2157-62.
Raggi P, Callister TQ, Cooil B, He ZX, Lippolis NJ, Russo DJ, et al. Identification of patients at increased risk of first unheralded acute myocardial infarction by electron-beam computed tomography. Circulation 2000;101: 850-5.
Detrano RC, Wong ND, Doherty TM, Shavelle RM, Tang W, Ginzton LE, et al. Coronary calcium does not accurately predict near term future coronary events in high risk adults. Circulation 1999;99: 2633-8.
O'Rourke RA, Brundage BH, Froelicher VF, Greenland P, Grundy SM, Hachamovitch R, et al. American College of Cardiology/American Heart Association expert consensus document on electron-beam computed tomography for the diagnosis and prognosis of coronary artery disease. Circulation 2000;102: 126-40.
Taillefer R, DePuey EG, Udelson JE, Beller GA, Benjamin C, Gagnon A. Comparison between the end-diastolic images and the summed images of gated 99mTc-sestamibi SPECT perfusion study in detection of coronary artery disease in women. J Nucl Cardiol 1999;6: 169-76.
Underwood SR, Godman B, Salyani S, Ogle JR, Ell PJ. Economics of myocardial perfusion imaging in Europe—the EMPIRE study. Eur Heart J 1999;20: 157-66.
Klocke FJ, Baird MG, Lorell BH, Bateman TM, Messer JV, Berman DS, et al. ACC/AHA/ASNC guidelines for the clinical use of cardiac radionuclide imaging—executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/ASNC Committee to Revise the 1995 Guidelines for the Clinical Use of Cardiac Radionuclide Imaging). J Am Coll Cardiol 2003;42(7): 1318-33.
Shaw LJ, Iskandrian AE, Hachamovitch R, Germano G, Lewin HC, Bateman TM, et al. Evidence-based risk assessment in noninvasive imaging. J Nucl Med 2001;42: 1424-36.
Maisel A. B type natriuretic peptide levels: diagnostic and prognostic in congestive heart failure. Circulation 2002;105: 2328.
Krishnaswamy P, Lubien E, Clopton P, Koon J, Kazanegra R, Wanner E, et al. Utility of B-natriuretic peptide levels in identifying patients with left ventricular systolic or diastolic dysfunction. Am J Med 2001;111: 274-9.
Chen HH, Burnett JC. Natriuretic peptides in the pathophysiology of congestive heart failure. Curr Cardiol Rep 2000;2: 198-205.
Harrison A, Morrison LK, Krishnaswamy P. B-type natriuretic peptide predicts future cardiac events in patients presenting to the emergency department with dyspnea. Ann Emerg Med 2002;39: 131-8.
Troughton RW, Frampton CM, Yandle TG, Espiner EA, Nicholls MG, Richards AM. Treatment of heart failure guided by plasma aminoterminal brain natriuretic peptide (N-BNP) concentrations. Lancet 2000;355: 1126-30.
Richards AM, Doughty R, Nicholls MG, MacMahon S, Sharpe N, Murphy J, et al. Plasma N-terminal pro-brain natriuretic peptide and adrenomedullin: prognostic utility and prediction of benefit from carvedilol in chronic ischemic left ventricular dysfunction. Australia-New Zealand Heart Failure Group. J Am Coll Cardiol 2001;37: 1781-7.
Maisel AS, Krishnaswamy P, Nowak RM, McCord J, Hollander JE, Duc P, et al. Rapid measurement of B-type natriuretic peptide in the emergency diagnosis of heart failure. N Engl J Med 2002;347: 161-7.
Hobbs FDR, Davis RC, Roalfe AK, Davies MK, Kenkre JE. Reliability of N-terminal pro-brain natriuretic peptide assay in diagnosis of heart failure: cohort study in representative and high risk community populations. BMJ 2002;324: 1498-500.
Heidenreich PA, Gubens MA, Fonarow GC, Konstam MA, Stevenson LW, Shekelle PG. Cost-effectiveness of screening with B-type natriuretic peptide to identify patients with reduced left ventricular ejection fraction. J Am Coll Cardiol 2004;43: 1019-26.(Sanjay K Prasad, consulta)