Editorial
Impact of SPECT myocardial perfusion imaging on cardiac care Expert Review of Cardiovascular Therapy Downloaded from informahealthcare.com by Nyu Medical Center on 10/12/14 For personal use only.
Expert Rev. Cardiovasc. Ther. Early online, 1–3 (2014)
Peter Lugomirski Author for correspondence: Division of Cardiology, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada [email protected]
Benjamin JW Chow Division of Cardiology, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada
Terrence D Ruddy Division of Cardiology, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada
Single photon emission computed tomography myocardial perfusion imaging is a powerful modality for the assessment of coronary artery disease. It is useful in the diagnosis of CAD, prognostication of CAD and the determination of viability. It acts as guide for therapy and has the ability to assess effectiveness of therapy. The use of SPECT myocardial perfusion imaging has also been shown to be cost–effective compared to other modalities in cardiology.
Significant technological advances have led to a significant increase in available noninvasive and invasive tests in clinical cardiology. These noninvasive tests include single-photon emission computed tomography (SPECT), positron emission tomography (PET), computed tomography (CT), MRI and 3D echocardiography. The new invasive tests include intravascular ultrasound, fractional flow reserve and optical coherence tomography. Although these tests use different techniques, some have overlapping capabilities and are used to answer similar clinical questions. SPECT myocardial perfusion imaging (MPI) remains to be the mainstay in the noninvasive evaluation of myocardial ischemia from obstructive coronary artery disease (CAD) and can be assessed using SPECT, PET, MRI and CT. SPECT is the most readily available MPI modality and has diagnostic and prognostic value. SPECT is a cost–effective modality that can be used to guide therapy and identify patients who may benefit from more invasive strategies. Traditionally, ECG stress testing has been advocated as a first-line test for patients with suspected CAD, normal ECGs and the ability to exercise. However, its diagnostic accuracy is suboptimal with a sensitivity and specificity of 68 and 77%, respectively. The sensitivity of ECG stress testing for single-vessel disease is lower at 50–55% [1].
The diagnostic accuracy of SPECT MPI has been well established and provides significant incremental information over ECG stress testing. In a meta-analysis of 33 studies, SPECT MPI had a sensitivity of 88% and specificity of 74%, with a normalcy rate of 91% [2]. The normalcy rate is a surrogate for specificity and is important because it accounts for verification bias. For example, patients who have a ‘normal SPECT MPI’ are less likely to be referred for invasive angiography than those with an abnormal study. Such bias in downstream testing results in a decrease in specificity. Therefore, normalcy rate (rate of normal studies in ‘normal patients’) accounts for such bias. When used in conjunction with SPECT MPI, there is no significant difference in diagnostic accuracy between exercise and pharmacological stress [2]. However, there is significant prognostic information gained from exercise stress. Exercise stress provides important information about exercise tolerance, arrhythmias, hemodynamic response to exertion and the presence of ST depression. Therefore, when possible, SPECT MPI should be combined with exercise stress. Compared to stress echocardiography, MPI is more sensitive for single-vessel and multi-vessel CAD [3]. SPECT MPI is especially useful for detecting ischemia in patients with resting regional wall motion abnormalities and conduction
KEYWORDS: clinical cardiology • coronary artery disease • myocardial perfusion imaging • SPECT
informahealthcare.com
10.1586/14779072.2014.965148
Ó 2014 Informa UK Ltd
ISSN 1477-9072
1
Expert Review of Cardiovascular Therapy Downloaded from informahealthcare.com by Nyu Medical Center on 10/12/14 For personal use only.
Editorial
Lugomirski, Chow & Ruddy
abnormalities and in patients with difficult echocardiographic windows such as obese patients and patients with COPD. SPECT MPI also offers important prognostic information. A normal scan has an excellent negative predictive value for future adverse cardiac events with very low annual rate of cardiovascular death or non-fatal myocardial infarction (0.6% per year) [4]. The low rates of adverse events are similarly low in higher pre-test risk populations such as those with diabetes [5]. This allows the clinician to confidently reassure the patient and avoid additional investigations. Conversely, the risk of adverse events increases exponentially, with the severity of perfusion abnormalities. Patients with a mildly abnormal scan have an event rate of 1.8% per year, while patients with moderate to severely abnormal scans have an event rate of approximately 7.0% per year [6]. Additional features that identify patients at high-risk include a large defect size, defects in multiple vascular territories, transient ischemic dilation, increased lung uptake or resting left ventricular (LV) ejection fraction
Impact of SPECT myocardial perfusion imaging on cardiac care Expert Review of Cardiovascular Therapy Downloaded from informahealthcare.com by Nyu Medical Center on 10/12/14 For personal use only.
Expert Rev. Cardiovasc. Ther. Early online, 1–3 (2014)
Peter Lugomirski Author for correspondence: Division of Cardiology, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada [email protected]
Benjamin JW Chow Division of Cardiology, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada
Terrence D Ruddy Division of Cardiology, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada
Single photon emission computed tomography myocardial perfusion imaging is a powerful modality for the assessment of coronary artery disease. It is useful in the diagnosis of CAD, prognostication of CAD and the determination of viability. It acts as guide for therapy and has the ability to assess effectiveness of therapy. The use of SPECT myocardial perfusion imaging has also been shown to be cost–effective compared to other modalities in cardiology.
Significant technological advances have led to a significant increase in available noninvasive and invasive tests in clinical cardiology. These noninvasive tests include single-photon emission computed tomography (SPECT), positron emission tomography (PET), computed tomography (CT), MRI and 3D echocardiography. The new invasive tests include intravascular ultrasound, fractional flow reserve and optical coherence tomography. Although these tests use different techniques, some have overlapping capabilities and are used to answer similar clinical questions. SPECT myocardial perfusion imaging (MPI) remains to be the mainstay in the noninvasive evaluation of myocardial ischemia from obstructive coronary artery disease (CAD) and can be assessed using SPECT, PET, MRI and CT. SPECT is the most readily available MPI modality and has diagnostic and prognostic value. SPECT is a cost–effective modality that can be used to guide therapy and identify patients who may benefit from more invasive strategies. Traditionally, ECG stress testing has been advocated as a first-line test for patients with suspected CAD, normal ECGs and the ability to exercise. However, its diagnostic accuracy is suboptimal with a sensitivity and specificity of 68 and 77%, respectively. The sensitivity of ECG stress testing for single-vessel disease is lower at 50–55% [1].
The diagnostic accuracy of SPECT MPI has been well established and provides significant incremental information over ECG stress testing. In a meta-analysis of 33 studies, SPECT MPI had a sensitivity of 88% and specificity of 74%, with a normalcy rate of 91% [2]. The normalcy rate is a surrogate for specificity and is important because it accounts for verification bias. For example, patients who have a ‘normal SPECT MPI’ are less likely to be referred for invasive angiography than those with an abnormal study. Such bias in downstream testing results in a decrease in specificity. Therefore, normalcy rate (rate of normal studies in ‘normal patients’) accounts for such bias. When used in conjunction with SPECT MPI, there is no significant difference in diagnostic accuracy between exercise and pharmacological stress [2]. However, there is significant prognostic information gained from exercise stress. Exercise stress provides important information about exercise tolerance, arrhythmias, hemodynamic response to exertion and the presence of ST depression. Therefore, when possible, SPECT MPI should be combined with exercise stress. Compared to stress echocardiography, MPI is more sensitive for single-vessel and multi-vessel CAD [3]. SPECT MPI is especially useful for detecting ischemia in patients with resting regional wall motion abnormalities and conduction
KEYWORDS: clinical cardiology • coronary artery disease • myocardial perfusion imaging • SPECT
informahealthcare.com
10.1586/14779072.2014.965148
Ó 2014 Informa UK Ltd
ISSN 1477-9072
1
Expert Review of Cardiovascular Therapy Downloaded from informahealthcare.com by Nyu Medical Center on 10/12/14 For personal use only.
Editorial
Lugomirski, Chow & Ruddy
abnormalities and in patients with difficult echocardiographic windows such as obese patients and patients with COPD. SPECT MPI also offers important prognostic information. A normal scan has an excellent negative predictive value for future adverse cardiac events with very low annual rate of cardiovascular death or non-fatal myocardial infarction (0.6% per year) [4]. The low rates of adverse events are similarly low in higher pre-test risk populations such as those with diabetes [5]. This allows the clinician to confidently reassure the patient and avoid additional investigations. Conversely, the risk of adverse events increases exponentially, with the severity of perfusion abnormalities. Patients with a mildly abnormal scan have an event rate of 1.8% per year, while patients with moderate to severely abnormal scans have an event rate of approximately 7.0% per year [6]. Additional features that identify patients at high-risk include a large defect size, defects in multiple vascular territories, transient ischemic dilation, increased lung uptake or resting left ventricular (LV) ejection fraction
