ICare-ACS (Improving Care Processes for Patients With Suspected Acute Coronary Syndrome): A Study of Cross-System Implementation of a National Clinical Pathway.

BACKGROUND: Efforts to safely reduce length of stay for emergency department patients with symptoms suggestive of acute coronary syndrome (ACS) have had mixed success. Few system-wide efforts affecting multiple hospital emergency departments have ever been evaluated. We evaluated the effectiveness of a nationwide implementation of clinical pathways for potential ACS in disparate hospitals. METHODS: This was a multicenter pragmatic stepped-wedge before-and-after trial in 7 New Zealand acute care hospitals with 31 332 patients investigated for suspected ACS with serial troponin measurements. The implementation was a clinical pathway for the assessment of patients with suspected ACS that included a clinical pathway document in paper or electronic format, structured risk stratification, specified time points for electrocardiographic and serial troponin testing within 3 hours of arrival, and directions for combining risk stratification and electrocardiographic and troponin testing in an accelerated diagnostic protocol. Implementation was monitored for >4 months and compared with usual care over the preceding 6 months. The main outcome measure was the odds of discharge within 6 hours of presentation RESULTS: There were 11 529 participants in the preimplementation phase (range, 284-3465) and 19 803 in the postimplementation phase (range, 395-5039). Overall, the mean 6-hour discharge rate increased from 8.3% (range, 2.7%-37.7%) to 18.4% (6.8%-43.8%). The odds of being discharged within 6 hours increased after clinical pathway implementation. The odds ratio was 2.4 (95% confidence interval, 2.3-2.6). In patients without ACS, the median length of hospital stays decreased by 2.9 hours (95% confidence interval, 2.4-3.4). For patients discharged within 6 hours, there was no change in 30-day major adverse cardiac event rates (0.52% versus 0.44%; P=0.96). In these patients, no adverse event occurred when clinical pathways were correctly followed. CONCLUSIONS: Implementation of clinical pathways for suspected ACS reduced the length of stay and increased the proportions of patients safely discharged within 6 hours. CLINICAL TRIAL REGISTRATION: URL: https://www.anzctr.org.au/ (Australian and New Zealand Clinical Trials Registry). Unique identifier: ACTRN12617000381381.

Quantification of coronary plaque by 64-slice computed tomography: a comparison with quantitative intracoronary ultrasound.

BACKGROUND: Noninvasive assessment of coronary atherosclerotic plaque may be useful for risk stratification and treatment of atherosclerosis. MATERIALS AND METHODS: We studied 47 patients to investigate the accuracy of coronary plaque volume measurement acquired with 64-slice multislice computed tomography (MSCT), using newly developed quantification software, when compared with quantitative intracoronary ultrasound (QCU). Quantitative MSCT coronary angiography (QMSCT-CA) was performed to determine plaque volume for a matched region of interest (regional plaque burden) and in significant plaque defined as a plaque with > or =50% area obstruction in QCU, and compared with QCU. Dataset with image blurring and heavy calcification were excluded from analysis. RESULTS: In 100 comparable regions of interest, regional plaque burden was highly correlated (coefficient r = 0.96; P < 0.001) between QCU and QMSCT-CA, but QMSCT-CA overestimated the plaque burden by a mean difference of 7 +/- 33 mm3 (P = 0.03). In 76 significant plaques detected within the regions of interest, plaque volume determined by QMSCT-CA was highly correlated (r = 0.98; P < 0.001) with a slight underestimation of 2 +/- 17 mm3 (P = not significant) when compared with QCU. Calcified and mixed plaque volume was slightly overestimated by 4 +/- 19 mm3 (P = ns) and noncalcified plaque volume was significantly underestimated by 9 +/- 11 mm3 (P < 0.001) with QMSCT-CA. Overall, the limits of agreement for plaque burden/volume measurement between QCU and QMSCT-CA were relatively large. Reproducibility for the measurements of regional plaque burden with QMSCT-CA was good, with a mean intraobserver and interobserver variability of 0% +/- 16% and 4% +/- 24%, respectively. CONCLUSIONS: Quantification of coronary plaque within selected proximal or middle coronary segments without image blurring and heavy calcification with 64-slice CT was moderately accurate with respect to intravascular ultrasound and demonstrated good reproducibility. Further improvement in CT resolution is required for more reliable measurement of coronary plaques using quantification software.

Relationships between vascular calcification, calcium metabolism, bone density, and fractures.

Factors involved with calcium metabolism, such as serum calcium and phosphate and calcium intake, have been associated with vascular disease in different populations. We investigated whether this association is mediated via increased vascular calcification by assessing relationships between these factors and abdominal aortic calcification (AAC) and coronary artery calcification (CAC). A total of 1471 healthy postmenopausal women participated in a 5-year randomized, placebo-controlled trial of calcium 1 g/day, and 323 healthy middle-aged and older men participated in a 2-year randomized, placebo-controlled trial of calcium 600 or 1200 mg/day. AAC was assessed on vertebral morphometric images at baseline and follow-up. Based on computed tomography, 163 men had CAC assessed, on average, 1.5 years after study completion. In elderly women, AAC was positively related to serum calcium (p < .001), phosphate (p = .04), and the calcium-phosphate product (p = .003), but changes in AAC over time and incidence of cardiovascular events were not related to these variables. In middle-aged men, AAC and CAC were not consistently related to these variables. Neither dietary calcium intake nor calcium supplementation was associated with changes in the prevalence of AAC over time, and calcium supplementation also was not related to CAC scores in men. After adjusting for age, AAC was not associated with low bone mineral density (BMD) at baseline, changes in BMD over time, or fracture incidence. CAC also was not related to baseline BMD. In summary, serum calcium and phosphate are associated with AAC in older women, but dietary calcium intake and calcium supplementation were not associated with changes in AAC over 2 to 5 years.

Abdominal aortic calcification on vertebral morphometry images predicts incident myocardial infarction.

Abdominal aortic calcification (AAC) measured on spine X-rays is an established risk factor for cardiovascular disease. We investigated whether AAC assessed using vertebral morphometry and a recently developed scoring system (AAC-8) is reliable and associated with cardiovascular risk factors or events. A total of 1471 healthy postmenopausal women and 323 healthy middle-aged and older men participated in 5 and 2 year trials of calcium supplements, respectively. AAC-8 was assessed on vertebral morphometry images at baseline and follow-up. In addition, 163 men also had coronary artery calcification measured using computed tomography. Cardiovascular events during the trials were independently adjudicated. We found strong inter- and intrameasurer agreement for AAC-8 (kappa > 0.87). The prevalence of AAC increased with age (p < .01) in women and in men. AAC was associated with many established cardiovascular risk factors, with serum calcium in women (p = .002) and with higher coronary calcium scores in men (p = .03). Estimated 5 year cardiovascular risk increased with increasing AAC-8 score (p < .001) in women and in men. The presence of AAC independently predicted myocardial infarction (MI) in women [hazards ratio (HR) = 2.30, p = .007] and men (HR = 5.32, p = .04), even after adjustment for estimated cardiovascular risk in women. In women, AAC independently predicted cardiovascular events (MI, stroke, or sudden death) (HR = 1.74, p = .007), and changes in AAC-8 score over time were associated with MI and cardiovascular events, even after adjustment for estimated cardiovascular risk. In summary, scoring AAC on vertebral morphometric scans is a reproducible method of assessing cardiovascular risk that independently predicts incident MI and cardiovascular events, even after taking into account traditional cardiovascular risk factors.

Increased B-type natriuretic peptide is associated with an abnormal blood pressure response to exercise in asymptomatic aortic stenosis.

AIMS: Both raised plasma levels of B-type natriuretic peptide (BNP) and an abnormal exercise response predict adverse clinical outcomes in aortic stenosis (AS). This study examines the relationship between the response to treadmill exercise and plasma levels of BNP in AS. METHODS AND RESULTS: 34 asymptomatic patients with moderate or severe AS (mean valve area 0.96+/-0.3 cm(2)) and 15 age matched controls underwent echocardiography, treadmill exercise testing, and BNP analysis. Compared to control subjects, AS patients had a higher left ventricular mass index, (133+/-50 vs 106+/-24 g/m(2), p=0.03), higher E/E' ratio, (10.6+/-3.6 vs 6.7+/-1.8, p=<0.0001), higher ejection fraction, (65+/-6 vs 59+/-6%, p=0.03), elevated resting BNP (11.4+/-6.5 vs 7.4+/-4.0 pmol/L, p=0.03) and shorter exercise duration (8.2+/-3.0 min vs 10.9+/-2.6 min, p=0.002). AS patients with an increase in systolic BP of 20 mmHg (13.8+/-6.1 vs 8.6+/-6.0 pmol/L, p=0.003). The BNP measured at peak exercise was also associated with the BP response (p=0.003). The area under the receiver operator curve to predict an abnormal BP response to exercise was 0.82 for BNP measured at rest but only 0.46 for aortic valve area. There was a modest association between raised BNP and lower exercise capacity. CONCLUSION: In patients with AS there is an association between BNP and an abnormal BP response to exercise. Further study is needed to determine the incremental prognostic value of BNP and exercise testing in asymptomatic AS.

Papillary fibroelastoma of the aortic valve and coronary artery disease visualized by 64-slice CT.

BACKGROUND: A 75-year-old male with a history of myocardial infarction and recent transient ischemic attack was referred to a cardiology clinic for preoperative evaluation before a cystectomy. Transthoracic and transesophageal echocardiography revealed a mobile mass on the right coronary cusp of the aortic valve. Multislice CT demonstrated a significant narrowing in the proximal left anterior descending coronary artery. INVESTIGATIONS: Physical examination, chest radiography, laboratory testing, electrocardiography, transthoracic and transesophageal echocardiography, multislice-CT coronary angiography, pathological and histological examination of the surgically excised tissue. DIAGNOSIS: Papillary fibroelastoma of the aortic valve in conjunction with coronary artery disease. MANAGEMENT: Surgical excision of the mobile lesion and an end-to-side anastomosis of the left internal mammary artery to the left anterior descending coronary artery.

Longitudinal left ventricular contractile dysfunction after exercise in aortic stenosis.

OBJECTIVE: To determine whether longitudinal left ventricular systolic function measured by Doppler tissue imaging (DTI) after exercise can identify early left ventricular dysfunction in asymptomatic patients with moderate-severe aortic stenosis. DESIGN: Case-control study. SETTING: Outpatient cardiology departments. PATIENTS: 20 patients with aortic stenosis, with or without equivocal symptoms, a peak aortic valve velocity > or =3 m/s, and left ventricular ejection fraction >50% and 15 aged-matched normal controls. INTERVENTIONS: Echocardiogram performed at rest and immediately after treadmill exercise. MAIN OUTCOME MEASURES: The peak systolic velocity of the lateral mitral annulus (S') by DTI at rest and immediately after exercise, exercise capacity, exercise systolic blood pressure and the plasma level of B-type natriuretic peptide (BNP). RESULTS: For patients with aortic stenosis, mean (SD) aortic valve area was 0.95 (0.3) cm(2). At rest, S' was similar for patients with aortic stenosis and controls, respectively (8.5 (1.5) vs 9.1 (1.8) cm/s, p = 0.15). However, after exercise, S' (12.2 (3.2) vs 17 (2.8) cm/s, p<0.001) and the increase in S' between rest and exercise (4 (3) vs 7.9 (1.5) cm/s, p<0.001) were lower in patients with aortic stenosis. In patients with aortic stenosis, a smaller increase in S' after exercise was associated with lower exercise capacity (r = 0.5, p = 0.02), a smaller increase in exercise systolic blood pressure (r = 0.6, p = 0.005) and higher plasma level of BNP (r = 0.66, p = 0.002). CONCLUSION: In asymptomatic patients with moderate-severe aortic stenosis a lower than normal increase in peak systolic mitral annular velocity after treadmill exercise is a marker of early left ventricular systolic dysfunction.