Dobutamine-atropine stress myocardial perfusion SPECT imaging in the diagnosis of graft stenosis after coronary artery bypass grafting

Diagnostic and Management Strategies in Patients with Late Recurrent Angina after Coronary Artery Bypass Grafting

PURPOSE OF REVIEW

This review will outline the current evidence on the anatomical, functional, and physiological tools that may be applied in the evaluation of patients with late recurrent angina after coronary artery bypass grafting (CABG). Furthermore, we discuss management strategies and propose an algorithm to guide decision-making for this complex patient population.

RECENT FINDINGS

Patients with prior CABG often present with late recurrent angina as a result of bypass graft failure and progression of native coronary artery disease (CAD). These patients are generally older, have a higher prevalence of comorbidities, and more complex atherosclerotic lesion morphology compared to CABG-naïve patients. In addition, guideline recommendations are based on studies in which post-CABG patients have been largely excluded. Several invasive and non-invasive diagnostic tools are currently available to assess graft patency, the hemodynamic significance of native CAD progression, left ventricular function, and myocardial viability. Such tools, in particular the latest generation coronary computed tomography angiography, are part of a systematic diagnostic work-up to guide optimal repeat revascularization strategy in patients presenting with late recurrent angina after CABG.

Comparison of the Diagnostic Performance of Myocardial Perfusion Scintigraphy with and Without Attenuation Correction

Objectives:

Myocardial perfusion scintigraphy (MPS) is an important diagnostic test for detecting of coronary artery stenosis (CAS); however, tissue attenuation can lead to a difference in accuracy. We evaluated the diagnostic accuracy of attenuation-corrected (AC) and non-attenuation-corrected (NC) MPS for the detection of CAS.

Methods:

We retrospectively recruited patients who underwent invasive coronary angiography within 10 months after Tc-99m sestamibi MPS. The AC and NC perfusion images were analyzed separately, and each myocardial segment was scored based on relative uptake from 0 to 4. The summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) were calculated. The diagnostic performances were analyzed using the area under the curve (AUC) of the receiver operating characteristic curve.

Results:

From 117 patients, significant coronary stenosis was present in 66 patients (56%). The SSS and SRS obtained from NC-images were higher than those from AC, supporting the presence of attenuation artifacts in NC images. The AUC of SSS and SDS were significantly higher than those of SRS in both AC- and NC-images, but no significant difference was found between the AUC of SSS, and those of SDS. The optimal cut-offs were >12 for AC-SSS, >15 for NC-SSS, >4 for AC-SDS and >3 for NC-SDS. There was no statistically significant difference in the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy among AC-SSS, NC-SSS, AC-SDS, and NC-SDS.

Conclusion:

NC-based Tc-99m-sestamibi MPS promised comparable accuracy to AC images by using different cut-off values for diagnosis.

Invasive angiography and revascularization in patients with stable angina following prior coronary artery bypass grafting: Results from the East Denmark heart registry

BACKGROUND

There are limited data to guide the optimum approach to patients presenting with angina after coronary artery bypass grafting (CABG). Although often referred for invasive angiography, the effectiveness of this is unknown; angina may also result from diffuse distal or micro-vascular coronary disease and it is not known how often targets for intervention are identified.

METHODS

Retrospective review of 50,460 patients undergoing angiography in East Denmark between January 2010 and December 2014. Clinical and procedural data were prospectively stored in a regional electronic database. Follow-up data were available for all patients, by means of records linked to each Danish social security number.

RESULTS

In patients with prior CABG and stable angina (n = 2,309), diagnostic angiography led to revascularization in 574 (24.9%) cases. Chronic kidney disease (HR 1.93 [1.08-3.44], P = 0.027), significant angina (HR 1.49 [1.18-1.88], P = 0.006 for angina class ≥ II, and HR 2.04 [1.61-2.58], P < 0.001 for angina class ≥ III) and a positive pre-procedural stress test (HR 2.56 [1.42-4.60], P < 0.001) were independent predictors of revascularization. Stress testing was, however, used less frequently than in patients without prior CABG (17.2% vs. 24.2%, P < 0.001). The positive predictive values for subsequent revascularization were 47.8%, 51.4%, and 66.9% for exercise ECG, stress echocardiography, and myocardial perfusion scintigraphy (MPS), respectively.

CONCLUSIONS

Invasive angiography leads to revascularization in a quarter of patients with angina and prior CABG; the threshold for referral may be too low. Non-invasive stress testing predicts the need for revascularization but appears underused and MPS, in particular, may better identify patients likely to require revascularization. © 2016 Wiley Periodicals, Inc.

The evolution and investigation of native coronary arteries in patients after coronary stent implantation: a study by 320-detector CT angiography

To study the role of 320-detector coronary computed tomography angiography (CTA) in assessing native coronary arteries in patients treated with coronary stents. 123 patients with coronary stenting received both CTA and conventional coronary angiography (CCA) within 1 day. The clinical parameters, coronary calcium scoring, CTA and CCA were analyzed to determine the prevalence of significant stenosis of native coronary arteries (SSNCA), the predictive value of CTA and the factors correlating with SSNCA and newly developed SSNCA after stenting (NDSSNCAS), with CCA as the standard of reference, using both vessel-based analysis (VBA) and patient-based analysis (PBA). Both the source and the reconstructed images were analyzed by CTA. All native coronary arteries were interpretable independent of cardiac motion. CTA showed a sensitivity/specificity of 93.5%/97.3% and 92.5%/92.5% in diagnosing SSNCA in VBA and PBA, respectively. The significant factors related to SSNCA were higher calcium scores (P = 0.003), a higher serum glucose level (P = 0.048), a greater number of vessels without previous stent placement (P = 0.003) and fewer stents implanted within the vessels (P = 0.003). The risk factors showed no significant correlation from PBA on SSNCA or from NDSSNCAS on either VBA or PBA. CTA demonstrates excellent correlation with CCA. The prevalence of SSNCA is significantly correlated with the presence of higher calcium scores in the arteries, a higher serum glucose level, a greater number of vessels without previous stent placement and fewer stents implanted within the vessels; PBA on SSNCA and NDSSNCAS on both VBA and PBA showed no significance.

Diagnostic performance of 320-slice multidetector computed tomography coronary angiography in patients after coronary artery bypass grafting

Objectives

To evaluate the diagnostic performance of 320-slice computed tomography coronary angiography (CTA) in the evaluation of patients with prior coronary artery bypass grafting (CABG). Invasive coronary angiography (ICA) served as the standard of reference, using a quantitative approach.

Methods

CTA studies were performed using CT equipment with 320 detector-rows, each 0.5 mm wide, and a gantry rotation time of 0.35 s. All grafts, recipient and nongrafted vessels were deemed interpretable or uninterpretable. The presence of significant (≥50%) stenosis and occlusion were determined on vessel and patient basis. Results were compared to ICA using quantitative coronary angiography.

Results

A total of 40 patients (28 men, 76 ± 15 years), with 89 grafts, were included in the study. On a graft analysis, the sensitivity, specificity, positive and negative predictive values in the evaluation of significant stenosis were 96%, 92%, 83% and 98% respectively. The diagnostic accuracy for the assessment of recipient and nongrafted vessels was 89% and 80%, respectively. The diagnostic accuracy for the assessment of graft, recipient and nongrafted vessel occlusion was 96%, 92% and 100%, respectively.

Conclusions

320-slice CTA allows accurate non-invasive assessment of significant graft, recipient vessel and nongrafted vessel stenosis in patients with prior CABG.

Noninvasive Diagnosis of Coronary Artery Bypass Graft Disease by Dobutamine Stress Real-time Myocardial Contrast Perfusion Imaging

BACKGROUND

The aim of this study was to assess the accuracy of real-time myocardial contrast perfusion imaging (MCPI) during dobutamine stress echocardiography, for the diagnosis of coronary artery bypass graft disease.

METHODS

MCPI was performed using commercially available ultrasound contrast agents (Optison or Definity) at rest and at peak dobutamine-atropine stress in 64 patients with previous coronary artery bypass graft. Significant disease was defined as 70% or greater stenosis in one or more grafts or a native nongrafted coronary artery. MCPI was considered diagnostic in the presence of reversible perfusion abnormalities (RPA).

RESULTS

Significant stenosis (>or=70% by quantitative angiography) in one or more grafts was detected in 49 patients (77%). RPA were detected in 44 of these patients (sensitivity 90%, confidence interval [CI] 81-98). Significant stenosis was detected in 74 of the 176 bypass grafts (42%). RPA were detected in the distribution of 55 diseased grafts and 21 nondiseased grafts (regional sensitivity 74%, CI 64-84; specificity 79%, CI 71-87; and accuracy 77%, CI 71-84). RPA were detected in two or more vascular distributions in 25 of 33 patients with multivessel stenotic lesions and in 4 of 31 patients without (sensitivity 76%, CI 61-90; specificity 87%, CI 75-99; and accuracy 81%, CI 72-91).

CONCLUSION

Dobutamine stress MCPI is a useful technique for the evaluation of coronary artery bypass graft disease.

Myocardial perfusion scintigraphy: the evidence

This review summarises the evidence for the role of myocardial perfusion scintigraphy (MPS) in patients with known or suspected coronary artery disease. It is the product of a consensus conference organised by the British Cardiac Society, the British Nuclear Cardiology Society and the British Nuclear Medicine Society and is endorsed by the Royal College of Physicians of London and the Royal College of Radiologists. It was used to inform the UK National Institute of Clinical Excellence in their appraisal of MPS in patients with chest pain and myocardial infarction. MPS is a well-established, non-invasive imaging technique with a large body of evidence to support its effectiveness in the diagnosis and management of angina and myocardial infarction. It is more accurate than the exercise ECG in detecting myocardial ischaemia and it is the single most powerful technique for predicting future coronary events. The high diagnostic accuracy of MPS allows reliable risk stratification and guides the selection of patients for further interventions, such as revascularisation. This in turn allows more appropriate utilisation of resources, with the potential for both improved clinical outcomes and greater cost-effectiveness. Evidence from modelling and observational studies supports the enhanced cost-effectiveness associated with MPS use. In patients presenting with stable or acute chest pain, strategies of investigation involving MPS are more cost-effective than those not using the technique. MPS also has particular advantages over alternative techniques in the management of a number of patient subgroups, including women, the elderly and those with diabetes, and its use will have a favourable impact on cost-effectiveness in these groups. MPS is already an integral part of many clinical guidelines for the investigation and management of angina and myocardial infarction. However, the technique is underutilised in the UK, as judged by the inappropriately long waiting times and by comparison with the numbers of revascularisations and coronary angiograms performed. Furthermore, MPS activity levels in this country fall far short of those in comparable European countries, with about half as many scans being undertaken per year. Currently, the number of MPS studies performed annually in the UK is 1,200/million population/year. We estimate the real need to be 4,000/million/year. The current average waiting time is 20 weeks and we recommend that clinically appropriate upper limits of waiting time are 6 weeks for routine studies and 1 week for urgent studies.

Long-term outcome of a residual scar from myocardial infarction after coronary artery bypass grafting: a 100-month study using myocardial perfusion scintigraphy

The prognosis for patients with a residual scar from myocardial infarction (MI) after coronary artery bypass grafting surgery (CABG) has not been fully evaluated, so the present study retrospectively evaluated such patients with stress myocardial single photon emission computed tomography (SPECT) at 100 months after CABG. The study group consisted of 24 subjects (23 males, 1 female; mean age, 59+/-9 years) in whom CABG had been performed more than 100 months (mean follow-up period 135+/-25 months) previously. The 24 subjects were classified into 3 groups according to their summed stress score (SSS) and summed reversibility score (SRS) in the early period after CABG. Eight subjects with MI (SSS> or =2 and SRS<2) were classified into the group MI, 8 subjects with ischemic myocardium (SSS> or =2 and SRS> or =2) was classified into the group RE, and 8 subjects with normal perfusion (SSS<2 and SRS<2) was classified into group N. None of the subjects in group MI required revascularization. Cardiac events occurred in 4 of the group RE patients and all required revascularization. As to the SPECT scoring system, the long-term SSS of group MI (6.4+/-3.1) was not different from that in the early periods (4.3+/-4.0; NS). However, the long-term SSS values of group RE (8.8+/-6.2) were significantly greater than those soon after CABG (3.4+/-1.8; p=0.03). In group N, there was also no difference in the SSS values between the early period (0.3+/-0.5) and the long-term period (0.0+/-0.0; NS). Patients with a residual scar from MI in the early period after CABG did not worsen over a period of 100 months. Moreover, there was no significant difference in the SPECT score in the segment with the residual scar in the short or long term after CABG. However, the extent of reversibility was directly associated with the presence of clinical events. Therefore scintigraphic imaging remains an important and clinically relevant risk stratification tool. Stress myocardial SPECT, early after CABG, can be used to predict the possibility of future cardiac events or the need for revascularization.