Diagnostic role of coronary calcium scoring in the rapid access chest pain clinic: prospective evaluation of NICE guidance.

BACKGROUND: Coronary artery calcium (CAC) imaging by unenhanced computed X-ray tomography (CT) is recommended as an initial diagnostic test for patients with stable chest pain symptoms but a low likelihood (10-29%) of underlying obstructive coronary artery disease (CAD) after clinical assessment. The recommendation has not previously been tested prospectively in a rapid access chest pain clinic (RACPC). METHODS: We recruited 300 consecutive patients presenting with stable chest pain to the RACPC of three hospitals. All patients underwent CAC imaging, followed by invasive coronary angiography (ICA) in patients with CAC ≥ 1000 Agatston units (Au) and CT coronary angiography (CTCA) in those with CAC <1000. Patients with 50-70% stenosis on CTCA underwent myocardial perfusion scintigraphy (MPS) while those with ≥ 70% stenosis underwent ICA. Obstructive CAD was defined as ≥ 70% stenosis on ICA or the presence of inducible ischaemia on MPS. Patients were followed up clinically for a mean of 17 (SD 6) months. RESULTS: The mean patient age was 60.6 (SD 9.6) years and 48% were males. Obstructive CAD was found in 56 (19%) patients, of whom 42 (14%) underwent revascularization. CAC was zero in 131 (44%) patients, of whom two (1.5%) had obstructive CAD and one (0.8%) underwent revascularization. The sensitivity, specificity, negative predictive value, and positive predictive value of CAC ≥ 1 for detection of obstructive CAD were 96, 53, 32, and 98%, respectively. None of the 57 patients with low pre-test probability of CAD and zero CAC had obstructive CAD or suffered a cardiovascular event during the follow-up. CONCLUSION: Patients with stable chest pain symptoms but a low likelihood of CAD can safely be diagnosed as not having obstructive CAD in the absence of detectable coronary calcification by unenhanced CT. Patients with CAC >400 Au have a high prevalence of obstructive CAD and further investigation with ICA or functional imaging may be warranted rather than CTCA. These findings support NICE guidance for the investigation of stable chest pain. ClinicalTrials gov identifier: NCT01464203.

Angioplasty of acquired pulmonary vein stenosis using covered stent.

One of the most serious complications post-catheter ablation of atrial fibrillation is the development of pulmonary vein stenosis. Controversy currently exists about the optimal treatment approach. The use of balloons and larger stents (~10 mm) results in more optimal outcome than just balloon angioplasty alone; however, even with stent implantation, recurrent restenosis may occur in 30 to 50% of patients. We report the case of a 28-year-old man who developed recurrent left inferior pulmonary vein stenosis following radiofrequency ablation for atrial fibrillation. This was initially stented with good result but soon after developed restenosis and required balloon angioplasty. Following the third episode of restenosis, stenting of the pulmonary vein was performed using a covered stent. The pulmonary vein has remained patent for the last 5 years.

Radiation dose of CT coronary angiography in clinical practice: objective evaluation of strategies for dose optimization.

BACKGROUND: CT coronary angiography (CTCA) is an evolving modality for the diagnosis of coronary artery disease. Radiation burden associated with CTCA has been a major concern in the wider application of this technique. It is important to reduce the radiation dose without compromising the image quality. OBJECTIVES: To estimate the radiation dose of CTCA in clinical practice and evaluate the effect of dose-saving algorithms on radiation dose and image quality. METHODS: Effective radiation dose was measured from the dose-length product in 616 consecutive patients (mean age 58 ± 12 years; 70% males) who underwent clinically indicated CTCA at our institution over 1 year. Image quality was assessed subjectively using a 4-point scale and objectively by measuring the signal- and contrast-to-noise ratios in the coronary arteries. Multivariate linear regression analysis was used to identify factors independently associated with radiation dose. RESULTS: Mean effective radiation dose of CTCA was 6.6 ± 3.3 mSv. Radiation dose was significantly reduced by dose saving algorithms such as 100 kV imaging (-47%; 95% CI, -44% to -50%), prospective gating (-35%; 95% CI, -29% to -40%) and ECG controlled tube current modulation (-23%; 95% CI, -9% to -34%). None of the dose saving algorithms were associated with a significant reduction in mean image quality or the frequency of diagnostic scans (P = non-significant for all comparisons). CONCLUSION: Careful application of radiation-dose saving algorithms in appropriately selected patients can reduce the radiation burden of CTCA significantly, without compromising the image quality.

Evaluation of graft patency by computed tomographic angiography in symptom-free post-coronary artery bypass surgery patients.

BACKGROUND: Accelerated atherosclerosis occurs in aortocoronary saphenous vein grafts, contributing to increased morbidity and mortality rates. We estimated the prevalence of asymptomatic graft failure in patients 5 years or more after coronary artery bypass grafting (CABG) using electron-beam computed tomographic angiography (EBA). METHODS AND RESULTS: EBA was performed in 45 symptom-free patients (mean age, 66 +/- 9 years; 87% male; mean time interval after CABG, 8 +/- 5 years). A total of 102 vein grafts and 37 internal mammary artery grafts were evaluated. Patients with graft stenosis or occlusion on EBA underwent myocardial perfusion scintigraphy and invasive angiography. Six grafts were unevaluable by EBA. Twenty patients had evidence of graft stenosis or occlusion on EBA. Of 20 asymptomatic patients with graft disease, 17 (85%) had abnormal myocardial perfusion, with moderate to severe reversible ischemia occurring in one third of subjects. Fourteen occluded and eleven stenosed vein grafts were correctly diagnosed by EBA. There were 2 false-positive EBA diagnoses of graft stenosis, resulting in a 100% positive predictive accuracy for detecting graft occlusion and 85% positive predictive accuracy for detecting graft stenosis. All occluded internal mammary artery grafts (n = 3) were accurately diagnosed. CONCLUSION: Computed tomographic coronary angiography permits reliable identification of bypass graft stenoses and occlusions in symptom-free patients more than 5 years after CABG. Future studies are needed to assess the prognostic benefit of early detection of graft disease and intervention in asymptomatic patients.

Determinants of progression of coronary artery calcification in type 2 diabetes role of glycemic control and inflammatory/vascular calcification markers.

OBJECTIVES: This study prospectively evaluated the relationship between cardiovascular risk factors, selected biomarkers (high-sensitivity C-reactive protein [hs-CRP], interleukin [IL]-6, and osteoprotegerin [OPG]), and the progression of coronary artery calcification (CAC) in type 2 diabetic subjects. BACKGROUND: Coronary artery calcification is pathognomonic of coronary atherosclerosis. Osteoprotegerin is a signaling molecule involved in bone remodeling that has been implicated in the regulation of vascular calcification and atherogenesis. METHODS: Three hundred ninety-eight type 2 diabetic subjects without prior coronary disease or symptoms (age 52 +/- 8 years, 61% male, glycated hemoglobin [HbA(1)c] 8 +/- 1.5) were evaluated serially by CAC imaging (mean follow-up 2.5 +/- 0.4 years). Progression/regression of CAC was defined as a change > or =2.5 between the square root transformed values of baseline and follow-up volumetric CAC scores. Demographic data, risk factors, glycemic control, medication use, serum hs-CRP, IL-6, and plasma OPG levels were measured at baseline and follow-up. RESULTS: Two hundred eleven patients (53%) had CAC at baseline. One hundred eighteen patients (29.6%) had CAC progression, whereas 3 patients (0.8%) had regression. Age, male gender, hypertension, baseline CAC, HbA(1)c >7, waist-hip ratio, IL-6, OPG, use of beta-blockers, calcium channel antagonists, angiotensin-converting enzyme (ACE) inhibitors, statins, and Framingham/UKPDS (United Kingdom Prospective Diabetes Study) risk scores were univariable predictors of CAC progression. In the multivariate model, baseline CAC (odds ratio [OR] for CAC >400 = 6.38, 95% confidence interval [CI] 2.63 to 15.5, p < 0.001), HbA(1)c >7 (OR 1.95, CI 1.08 to 3.52, p = 0.03), and statin use (OR 2.27, CI 1.38 to 3.73, p = 0.001) were independent predictors of CAC progression. CONCLUSIONS: Baseline CAC severity and suboptimal glycemic control are strong risk factors for CAC progression in type 2 diabetic subjects.

Risk stratification in uncomplicated type 2 diabetes: prospective evaluation of the combined use of coronary artery calcium imaging and selective myocardial perfusion scintigraphy.

AIMS: To determine the prevalence and clinical predictors of subclinical atherosclerosis and myocardial ischaemia in uncomplicated type 2 diabetes and assess their relationship to short-term outcome. METHODS AND RESULTS: Established risk factors and coronary artery calcium (CAC) scores were prospectively measured in 510 asymptomatic type 2 diabetic subjects (mean age 53+/-8 years, 61% males) without prior cardiovascular disease. Myocardial perfusion scintigraphy (MPS) was performed in all subjects with CAC > 100 Agatston units (AU) (n=127), and a random sample of the remaining patients with CAC < or = 100 AU (n=53). Significant CAC (> 10 AU) was found in 46.3%. Twenty events occurred (two coronary deaths, nine non-fatal myocardial infarctions, three acute coronary syndromes, three non-haemorrhagic strokes, and three late revascularisations) during a median follow-up of 2.2 years (25th-75th percentile = 1.9-2.5 years). The age, systolic blood pressure, the duration of diabetes, United Kingdom Prospective Diabetes Study risk score, CAC score, and extent of myocardial perfusion abnormality were significant predictors of time to cardiovascular events in a univariable Cox proportional hazard model. No cardiac events or perfusion abnormalities occurred in subjects with CAC < or = 10 AU up until 2 years of follow-up. CAC and MPS findings were synergistic for the prediction of short-term cardiovascular events. CONCLUSION: Subclinical atherosclerosis, measured by CAC imaging, is superior to the established cardiovascular risk factors for predicting silent myocardial ischaemia and short-term outcome. Further studies evaluating the impact of CAC imaging on clinical outcomes and its cost effectiveness are warranted.

Real-time myocardial contrast dobutamine stress echocardiography in coronary stenosis.

BACKGROUND: Simultaneous wall motion and myocardial perfusion analysis could offer advantages over either method alone. Diagnostic utility of combining these parameters during dobutamine stress echocardiography is evaluated in this study. METHODS: Myocardial contrast dobutamine stress echocardiography was performed on thirty-eight patients with single or double vessel coronary artery stenosis of >50%. Two-dimensional standard wall motion images were acquired at baseline, low, intermediate and peak stages of dobutamine stress echocardiography. Contrast enhanced wall motion and perfusion were assessed with Cadence Contrast Imaging (Sequoia C256, Acuson) and Optison infusion (GE Healthcare) at baseline and peak stages of the same protocol. Perfusion was analysed by identification of contrast defects and by measuring contrast replenishment time after destructive ultrasound pulses. RESULTS: The group consisted of 28 males and 10 females, mean age 60.9+/-9.7 years. Fifty-four out of one hundred and fourteen coronary arteries were affected by stenoses >50%. Standard wall motion analysis was assessable in 37 cases, one of which was inconclusive, while contrast wall motion and perfusion were assessable in 32 cases. Accuracy for coronary stenosis was 84% for standard wall motion (108 coronary territories), 82% for contrast wall motion (96 territories), 69% for peak stress contrast defects (83 territories), 91% for combined peak stress contrast defects and increased contrast replenishment time (85 territories), and 90% for all contrast modalities combined (96 territories). CONCLUSION: Combined wall motion and real-time perfusion assessment during dobutamine stress is feasible and at least equivalent to conventional stress echocardiography for detection of significant coronary stenosis.

Prevalence of silent myocardial ischemia in asymptomatic individuals with subclinical atherosclerosis detected by electron beam tomography.

BACKGROUND: Electron beam tomography coronary calcium imaging is an evolving technique for the early detection of coronary atherosclerosis, and recent studies have established its prognostic value in asymptomatic individuals. The relationship of coronary artery calcium scores (CAC) to obstructive coronary artery disease (CAD) has been poorly studied but is clinically relevant because it determines which individuals are likely to benefit from revascularization procedures. Hence, we prospectively evaluated the prevalence of myocardial ischemia in asymptomatic patients with cardiovascular risk factors and subclinical atherosclerosis. METHODS AND RESULTS: We studied 864 asymptomatic patients with no previous CAD but with cardiovascular risk factors, referred for electron beam tomography coronary calcium imaging to our institution over an 18-month period. From this group, 220 consecutive patients (85% men; mean age, 61 +/- 9 years; age range, 31-84 years) with moderate to severe atherosclerotic disease (coronary calcium score > or =100 Agatston units) were prospectively evaluated by technetium 99m sestamibi single photon emission computed tomography (SPECT). Patients were followed up (mean follow-up, 14 months) and data regarding their subsequent clinical management recorded. Of the 220 patients, 119 had moderate atherosclerosis (CAC score of 100-400 Agatston units) and 101 had severe atherosclerosis (CAC score > or =400 Agatston units). Abnormal SPECT findings were seen in 18% of patients with moderate atherosclerosis (n = 21) and 45% of patients with severe atherosclerosis (n = 45). Increasing severity of atherosclerosis was related to increasing ischemic burden (summed difference score = 1 +/- 0.2 for CAC score of 100-400 Agatston units and 3.2 +/- 0.5 for CAC score > or =400 Agatston units). In a multivariate linear regression model incorporating risk factors, CAC was the only predictor of silent ischemia. CONCLUSION: In comparison to previously published data, we detected a higher prevalence of silent ischemia even in patients with moderate coronary atherosclerosis (18%). This may reflect the differing risk factor profile of our patient population. When coronary calcium screening is used to preselect asymptomatic patients with cardiovascular risk factors for myocardial perfusion imaging, the optimum coronary calcium score threshold will depend on the population prevalence of risk factors and asymptomatic obstructive CAD.