Diagnostic and prognostic testing to evaluate coronary artery disease in patients with diabetes mellitus

Increased expression of Sonic hedgehog restores diabetic endothelial progenitor cells and improves cardiac repair after acute myocardial infarction in diabetic mice

Damaged endothelial progenitor cells (EPCs) are associated with poor prognosis in diabetic myocardial infarction (DMI). Our previous studies revealed that an impaired Sonic hedgehog (Shh) pathway contributes to insufficient function in diabetic EPCs; however, the roles of the Shh pathway in diabetic EPC apoptosis under basal and hypoxic/ischemic conditions remain unknown. Therefore, the present study investigated whether Shh revitalized diabetic EPCs and consequently improved the deteriorative status of DMI. For this purpose, streptozotocin injection was used in male C57/BL6 mice to induce type-1 diabetes, and diabetic EPCs were isolated from the bone marrow. Apoptosis, cell function, and protein expression were investigated in EPCs in vitro. Mouse hearts were injected with adenovirus Shh-modified diabetic EPCs (DM-EPC^Shh) or control DM-EPC^Null immediately after coronary artery ligation in vivo. Cardiac function, capillary numbers, fibrosis, and cell apoptosis were then detected. First, the in vitro results demonstrated that the apoptosis of diabetic EPCs was reduced following treatment with Shh protein for 24 h, under normal or hypoxic conditions. BMI1 proto-oncogene (Bmi1), an antiapoptotic protein found in several cells, was reduced in diabetic EPCs under normal or hypoxic conditions, but was upregulated after Shh protein stimulation. When Bmi1-siRNA was administered, the antiapoptotic effect of Shh protein was significantly reversed. In addition, p53, a Bmi1-targeted gene, was demonstrated to mediate the antiapoptotic effect of the Shh/Bmi1 pathway in diabetic EPCs. The Shh/Bmi1/p53 axis also enhanced the diabetic EPC function. In vivo, Shh-modified diabetic EPCs exhibited increased EPC retention and decreased apoptosis at 3 days post-DMI. At 14 days post-DMI, these cells presented enhanced capillary density, reduced myocardial fibrosis and improved cardiac function. In conclusion, the present results demonstrated that the Shh pathway restored diabetic EPCs through the Shh/Bmi1/p53 axis, suppressed myocardial apoptosis and improved myocardial angiogenesis, thus reducing cardiac fibrosis and finally restoring myocardial repair and cardiac function in DMI. Thus, the Shh pathway may serve as a potential target for autologous cell therapy in diabetic myocardial ischemia.

Impact of Diabetes Mellitus on the Evaluation of Stable Chest Pain Patients: Insights From the PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) Trial

Background

The impact of diabetes mellitus on the clinical presentation and noninvasive test (NIT) results among stable outpatients presenting with symptoms suggestive of coronary artery disease (CAD) has not been well described.

Methods and Results

The PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) trial enrolled 10 003 patients with known diabetic status, of whom 8966 were tested as randomized and had interpretable NIT results (1908 with diabetes mellitus, 21%). Differences in symptoms and NIT results were evaluated using logistic regression. Patients with diabetes mellitus (versus without) were similar in age (median 61 versus 60 years) and sex (female 54% versus 52%), had a greater burden of cardiovascular comorbidities, and had a similar likelihood of nonchest pain symptoms (29% versus 27%). The Diamond‐Forrester/Coronary Artery Surgery Study score predicted that patients with diabetes mellitus (versus without) had similar likelihood of obstructive CAD (low 1.8% versus 2.7%; intermediate 92.3% versus 92.6%; high 5.9% versus 4.7%). Physicians estimated patients with diabetes mellitus to have a higher likelihood of obstructive CAD (low to very low: 28.3% versus 40.1%; intermediate 63.9% versus 55.9%; high to very high 7.8% versus 4.0%). Patients with diabetes mellitus (versus without) were more likely to have a positive NIT result (15% versus 11%; adjusted odds ratio, 1.23; P=0.01).

Conclusions

Stable chest pain patients with and without diabetes mellitus have similar presentation and pretest likelihood of obstructive CAD; however, physicians perceive that patients with diabetes mellitus have a higher pretest likelihood of obstructive CAD, an assessment supported by increased risk of a positive NIT. Further evaluation of diabetes mellitus's influence on CAD assessment is required.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01174550.

Vascular imaging in diabetes

Diabetes is a global epidemic affecting individuals of all socioeconomic backgrounds. Despite intensive efforts, morbidity and mortality secondary to the micro- and macrovascular complications remain unacceptably high. As a result, the use of imaging modalities to determine the underlying pathophysiology, early onset of complications, and disease progression has become an integral component of the management of such individuals. Echocardiography, stress echocardiography, and nuclear imaging have been the mainstay of noninvasive cardiovascular imaging tools to detect myocardial ischemia, but newer modalities such as cardiac MRI, cardiac CT, and PET imaging provide incremental information not available with standard imaging. While vascular imaging to detect cerebrovascular and peripheral arterial disease non-invasively has traditionally used ultrasound, CT- and MRI-based techniques are increasingly being employed. In this review, we will provide an outline of recent studies utilizing non-invasive imaging techniques to assist in disease diagnosis as well as monitoring disease progression. In addition, we will review the evidence for newer modalities such as MR spectroscopy, 3D intravascular ultrasound, and optical coherence tomography that provide exquisite detail of metabolic function and coronary anatomy not available with standard imaging, but that have not yet become mainstream.

Coronary artery disease screening in type II diabetic patients: prognostic value of rest and stress echocardiography

AIM

Presence of inducible ischemia in type II diabetic patients is associated with an adverse outcome, but less is known about prognostic value of resting wall motion abnormalities (WMA).

MATERIALS AND METHODS

From October 2006 to May 2008, 278 patients underwent to CAD screening, according to ADA criteria, by dobutamine stress echocardiography (DSE). Between July and September 2009, all patients were contacted to verify the occurrence of new cardiac events.

RESULTS

Resting-WMA were present in 63 patients; 88 subjects showed inducible ischemia. During the follow-up, we observed 24 new cardiac events; patients with a good outcome showed less frequently resting WMA (19 vs 50%). Inducible ischemia (71% vs 28%; p<0.001) and a more extensive area of inducible ischemia, expressed by a higher value of peak WMSI (1.63±0.45 vs 1.17±0.31; p<0.0001), were more frequent in patients with adverse outcome. A Cox regression analysis showed that only a higher peak WMSI (HR 6.645, 95% CI 2.782-15.874, p<0.0001) was associated with a bad outcome. Event-free survival was lower in presence of rest WMA (79% vs 94%, p<0.0001) and a higher peak WMSI (66% vs 95%, p<0.0001).

CONCLUSIONS

In diabetic patients presence of an extensive inducible ischemia was independently associated with a worst outcome; resting WMA were associated with reduced event-free survival.

Diagnostic accuracy of exercise stress testing for coronary artery disease: a systematic review and meta-analysis of prospective studies

BACKGROUND

Exercise stress testing offers a non-invasive, less expensive way of risk stratification prior to coronary angiography, and a negative stress test may actually avoid angiography. However, previous meta-analyses have not included all exercise test modalities, or patients without known Coronary artery disease (CAD).

METHODS AND RESULTS

We systematically reviewed the literature to determine the diagnostic accuracy of exercise stress testing for CAD on angiography. MEDLINE (January 1966 to November 2009), MEDION (1966 to July 2009), CENTRAL (1966 to July 2009) and EMBASE (1980-2009) databases were searched for English language articles on diagnostic accuracy of exercise stress testing. We included prospective studies comparing exercise stress testing with a reference standard of coronary angiography in patients without known CAD. From 6,055 records, we included 34 studies with 3,352 participants. Overall, we found published studies regarding five different exercise testing modalities: treadmill ECG, treadmill echo, bicycle ECG, bicycle echo and myocardial perfusion imaging. The prevalence of CAD ranged from 12% to 83%. Positive and negative likelihood ratios of stress testing increased in low prevalence settings. Treadmill echo testing (LR+ = 7.94) performed better than treadmill ECG testing (LR+ = 3.57) for ruling in CAD and ruling out CAD (echo LR- = 0.19 vs. ECG LR- = 0.38). Bicycle echo testing (LR+ = 11.34) performed better than treadmill echo testing (LR+ = 7.94), which outperformed both treadmill ECG and bicycle ECG. A positive exercise test is more helpful in younger patients (LR+ = 4.74) than in older patients (LR+ = 2.8).

CONCLUSIONS

The diagnostic accuracy of exercise testing varies, depending upon the age, gender and clinical characteristics of the patient, prevalence of CAD and modality of test used. Exercise testing, whether by echocardiography or ECG, is more useful at excluding CAD than confirming it. Clinicians have concentrated on individualising the treatment of CAD, but there is great scope for individualising the diagnosis of CAD using exercise testing.

[Incidence and prognostic value of ischemic heart disease in high risk cardiovascular asymptomatic diabetic patients detected by gated myocardial perfusion SPECT study]

AIM

To determine the clinical utility of the gated myocardial perfusion SPECT to detect silent ischemia in asymptomatic diabetic patients without previous coronary events and to evaluate the prognosis of this population.

MATERIAL AND METHODS

A retrospective study of 56 asymptomatic diabetics referred for a gated myocardial perfusion SPECT for diagnosis of ischemic disease was performed. The criteria for ischemia were: mild SDS<4, moderate SDS 4-8, severe SDS>8. A multivariable statistical analysis was carried out to identify possible predictive variables of an abnormal SPECT. The cardiovascular events were recorded up to December-2010.

RESULTS

A high proportion of the 56 patients had an abnormal perfusion study (46.4%), there being moderate-severe ischemia in 10.7%, necrosis with ischemia in 5.4% and necrosis in 7.1%. We found no statistical differences in the type of stress used (treadmill or dipyridamole). The patients had a high combination of cardiovascular risk factors. In the multivariate analysis, diabetic nephropathy was the only factor related to an abnormal SPECT (p=0.043). The events recorded in the follow-up were: 2 early revascularizations, 5 cardiology admissions, 10 non-cardiac related deaths. The existence of ischemia in the SPECT was significantly related to the appearance of cardiovascular events (p<0.05).

CONCLUSION

A gated myocardial perfusion SPECT in asymptomatic diabetics with high combination of cardiovascular risk factors detects silent ischemia in a significant proportion and this seems to be related to future coronary events. Diabetic nephropathy implies a greater likelihood of abnormal studies. However, the screening criteria in this population still need to be established for better performance and lower cost.