Accuracy of dobutamine technetium 99m sestamibi SPECT imaging for the diagnosis of single-vessel coronary artery disease: Comparison with echocardiography

Accuracy of myocardial perfusion imaging in detecting multivessel coronary artery disease: A cardiac CZT study

BACKGROUND

Myocardial perfusion imaging (MPI) performed on traditional single-photon emission computed-tomography cameras has been shown to have a sub-optimal accuracy in detecting multivessel coronary artery disease (CAD).

METHODS

Six-hundred and ninety-five patients were submitted to MPI on a novel cadmium-zinc-telluride (CZT) camera and coronary angiography. A coronary stenosis >70% was considered obstructive. In every patient, the summed stress score (SSS) was computed. Moreover, the regional stress scores were also calculated for every coronary territory.

RESULTS

Four-hundred and forty-one patients had obstructive CAD in one (28%), two (19%), or three (17%) vessels. At per-patient analysis, the SSS showed a significant accuracy in detecting obstructive CAD (AUC 0.87, P < .001). Specifically, its accuracy was maintained also in patients with double (AUC 0.83; P < .001) or triple-vessels disease (AUC 0.79, P < .001), where CZT was able to correctly identify CAD extent in 64% of patients. On a per-vessel basis, CZT confirmed its high accuracy in detecting obstructive CAD (AUC 0.88, P < .001), independently from the involved coronary vessel.

CONCLUSIONS

MPI performed on a CZT camera is highly accurate in detecting obstructive CAD, independently from the coronary artery involved and the overall disease burden.

Detection of single-vessel coronary artery disease by dipyridamole stress echocardiography: no longer a problem?

We aimed to evaluate whether addition of myocardial contrast echocardiography (MCE) perfusion data improves the sensitivity of stress echocardiography for detection of single-vessel coronary artery disease (svCAD) and to compare the diagnostic value of MCE and single-photon emission computed tomography (SPECT) for detection of svCAD.

METHODS

One hundred and three patients with suspected or known stable CAD underwent dipyridamole (0.84 mg kg(-1) intravenously over 4 min)-atropine (up to 1 mg intravenously) stress echocardiography combined with MCE. Wall motion abnormalities (WMA) and perfusion defects were assessed visually. Presence of CAD was detected by coronary angiography.

RESULTS

Single-vessel coronary artery disease defined as >or=70% stenosis was detected in 30% of patients, whereas 26% of patients had svCAD defined as >or=50% stenosis. Presence of inducible WMA had 35% and 26% sensitivity for detection of svCAD defined as >or=70% and >or=50% stenosis, respectively. Concomitant evaluation of MCE increased the sensitivity to 74% (P = 0.005) and 56% (P = 0.053), respectively, using any inducible abnormality (WMA or perfusion defects) as a criterion. Presence of any (inducible or fixed) WMA had 77% and 59% sensitivity for detection of svCAD defined as >or=70% and >or=50% stenosis, respectively. In case of such criterion for stress test positivity, the improvement in sensitivity provided by addition of MCE (to 94% and 78%, respectively) did not reach statistical significance.

CONCLUSIONS

Addition of MCE perfusion analysis during stress echocardiographical examination based on evaluation of inducible abnormalities improves the test sensitivity for detection of svCAD. This benefit is less apparent when fixed WMA and perfusion defects are incorporated into the stress test positivity criterion.

Emerging cardiovascular imaging techniques to non-invasively detect coronary artery disease

The current reference standard for the non-invasive detection of coronary artery disease (CAD) in patients who present with symptoms suggestive of CAD is either an exercise or pharmacologic stress radionuclide examination. Although useful, this test is limited by its relatively poor spatial resolution, high cost and need for ionizing radiation. Alternative non-invasive tests that are now clinically available include rest or pharmacologic stress echocardiography, pharmacologic stress during magnetic resonance perfusion imaging and multislice computed tomographic coronary angiography. This paper will present the advantages and disadvantages of stress techniques, and new developments that will further improve the accuracy of these tests.

New technologies applied to stress echocardiography: myocardial contrast echocardiography

The development of new echocardiographic contrast agents that can be injected intravenously and can opacify left-sided cardiac chambers has offered a contribution in the field of stress-echocardiography for two main reasons: (1) the improvement of visualization of the endocardial border and thus facilitating recognition of wall motion abnormalities during pharmacological stress or physical exercise; and (2) the obtaining of information on myocardial perfusion during stress examinations. This review will consider: (1) the improvement of diagnostic accuracy during pharmacological stress or physical exercise obtained with the administration of echo-contrast agents; (2) the results of major studies for comparison of the myocardial contrast echocardiography technique versus single-photon emission computed tomography (SPECT) and coronary angiography; (3) the added value for studying perfusion other than wall motion analysis during stress echo; and (4) the advantages and limitations of different stress modalities. New multicenter studies should now definitively clarify the choice of the best contrast agents and create protocols for myocardial contrast echocardiography using different methods of image acquisition in order to unify the diagnostic process before a 'label approved' for perfusion of contrast echocardiographic agents. Finally, caution should be considered when contrast agents are used in the acute phase of myocardial infarction or ischemia.

Dobutamine myocardial scintigraphy for the prediction of cardiac events after heart transplantation

BACKGROUND

The long-term outcome after heart transplantation (HTx) is essentially influenced by the occurrence and extent of cardiac allograft vasculopathy (CAV). Single photon emission computed tomography-myocardial perfusion imaging (SPECT-MPI) has been shown to be a useful and cost-effective non-invasive method in patients with known or suspected coronary artery disease, but its role in detecting CAV remains unclear.

AIM

To evaluate the accuracy and predictive value of dobutamine MPI in patients after HTx during a 12-month follow-up.

METHODS

Seventy-seven patients (60 males, 17 females) underwent a total of 216 dobutamine MPI examinations over a period of 5 years. Examinations were obtained an average of 89+/-42 months after orthotopic HTx according to a 1-day protocol using 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) with and without attenuation correction. For the present study, findings from 77 MPI examinations (one MPI examination per patient) were analysed visually and semiquantitatively using a 20-segment model. Summed stress scores (SSS) and summed rest scores (SRS) were calculated and receiver operating characteristic (ROC) analysis was performed to detect optimum threshold values. Patients were followed up for 12 months and cardiac events were registered.

RESULTS

Cardiac events were observed in 10 of the 77 patients. Good interobserver agreement was found for global visual and SRS-/SSS-based analysis (kappa=0.74 and 0.66, respectively). SSS was superior to SRS in the detection of cardiac events. ROC analysis showed an optimized SSS threshold value of three. For predicting a cardiac event during the 12-month follow-up, global visual and semiquantitative analysis reached sensitivities of 90% and 90%, specificities of 72% and 88%, accuracies of 74% and 87%, positive predictive values of 32% and 53% and negative predictive values of 98% and 98%, respectively. The sensitivity, specificity, accuracy and positive and negative predictive values for MPI to detect clinically relevant coronary artery stenoses (> or =50%) at conventional coronary angiography were 83%, 87%, 86%, 56% and 96%, respectively.

CONCLUSIONS

Non-invasive dobutamine MPI reliably identifies patients at risk for subsequent cardiac events in cases of CAV, with a high negative predictive value of 98% and an accuracy of 87%.

Noninvasive diagnosis of coronary artery disease in patients with diabetes by dobutamine stress real-time myocardial contrast perfusion imaging

OBJECTIVE

The aim of this study was to assess the accuracy of real-time myocardial contrast perfusion imaging (MCPI) during dobutamine stress in the diagnosis and localization of coronary artery disease (CAD) in patients with diabetes. Myocardial contrast echocardiography is a new technique that allows evaluation of myocardial perfusion. Its utility in diabetic patients has not been defined.

RESEARCH DESIGN AND METHODS

Dobutamine-atropine stress test was performed in conjunction with MCPI using Optison or Definity at rest and at peak stress in 128 patients with diabetes and suspected CAD who underwent coronary angiography within 1 month. CAD was defined as > or =50% stenosis in one or more coronary artery. MCPI was considered diagnostic of CAD in the presence of reversible perfusion abnormalities. The normalcy rate of MCPI was additionally determined in 18 asymptomatic nondiabetic patients with low probability.

RESULTS

CAD was detected in 101 (79%) patients by angiography. Reversible perfusion abnormalities were detected in 90 patients with and 13 patients without CAD. The overall sensitivity of MCPI was 89% (95% CI 83-95), specificity 52% (33-71), and accuracy 81% (75-88). Reversible abnormalities were detected in two or more vascular distributions in 44 of 56 patients with multivessel CAD and in 8 of 63 patients without (sensitivity 68%, specificity 87%, positive predictive value 84%, and accuracy 79%). Regional sensitivity was 75% (65-85) for left anterior descending CAD, 71% (60-83) for left circumflex, and 67% (55-78) for right CAD. MCPI was normal in 16 of the 18 patients with low clinical probability of CAD (normalcy rate 89%).

CONCLUSIONS

MCPI is a useful noninvasive technique for the diagnosis and localization of CAD in diabetic patients. The extent of perfusion abnormalities can identify patients with multivessel CAD with a moderate sensitivity and high specificity.

Comparative accuracy of real-time myocardial contrast perfusion imaging and wall motion analysis during dobutamine stress echocardiography for the diagnosis of coronary artery disease

OBJECTIVE

This study sought to compare the accuracy of myocardial contrast echocardiography (MCE) and wall motion analysis (WMA) during submaximal and peak dobutamine stress echocardiography (DSE) for the diagnosis of coronary artery disease (CAD).

BACKGROUND

The relative merits of MCE and WMA for the detection of CAD during DSE have not been studied in a large number of patients.

METHODS

We studied 170 patients who underwent dobutamine (up to 50 microg/kg/min)-atropine stress testing and coronary angiography. The WMA and MCE (using repeated boluses of Optison [Mallinckrodt, St. Louis, Missouri] or Definity [Bristol-Myers Squibb, New York, New York]) were performed at rest, at intermediate stress (65% to 75% of maximal heart rate), and at peak stress. The diagnosis of CAD (>/=50% stenosis in >/=1 coronary artery) was based on reversible wall motion and perfusion abnormalities.

RESULTS

Coronary artery disease was detected in 127 (75%) patients. Sensitivity of MCE was higher than that of WMA at maximal stress (91% vs. 70%; p = 0.001) and at intermediate stress (84% vs. 20%; p = 0.0001). Specificity was lower for MCE compared with WMA (51% vs. 74%; p = 0.01). Overall accuracy was higher for MCE than for WMA (81% vs. 71%; p = 0.01). Sensitivity for detection of CAD based on abnormalities in >/=2 vascular regions was higher for MCE than for WMA (67% vs. 28%; p < 0.01).

CONCLUSIONS

The majority of inducible perfusion abnormalities occur at an intermediate phase of the stress test, without wall motion abnormalities. Myocardial contrast echocardiography provides better sensitivity than WMA, particularly in patients with submaximal stress and in identifying patients with multivessel CAD.

Use of pharmaceuticals in noninvasive cardiovascular diagnosis

A number of pharmaceuticals are employed as diagnostic agents for cardiovascular diseases. Four groups of agents are reviewed here: 1) vasoactive substances employed as adjuncts to physical maneuvers in diagnosis of structural heart disease; 2) vasodilators used to produce heterogeneity of coronary flow; 3) sympathomimetic agents simulating the effects of exercise on the heart for the purpose of detection of coronary artery stenosis; and 4) ultrasonic contrast agents used to enhance myocardial imaging for the assessment of segmental wall motion. In the first group are amyl nitrate, a vasodilator, and methoxamine and phenylephrine, both vasopressors. The vasodilators of the second group are dipyridamole and adenosine. When combined with scintigraphic perfusion imaging or with echocardiographic assessment of segmental wall motion, these agents can detect single- or multiple-vessel coronary artery disease with sensitivity and specificity comparable to submaximal exercise. They are especially useful for preoperative risk assessment before noncardiac surgery. The sympathomimetic agents of the third group, dobutamine and arbutamine, increase myocardial contractility and heart rate, and dilate the peripheral vasculature. As with the vasodilators, when combined with nuclear or echocardiographic techniques they are equivalent to exercise in detection of coronary disease. They are especially useful in patients with bronchospastic disease and for assessment of myocardial viability. Agents from groups 2 and 3 have acceptable side-effect and safety profiles. The last group reviewed includes echocardiographic contrast agents that, in this investigative setting, are employed to enhance detection of segmental wall motion when used with agents from groups 2 and 3.