Electron-beam computed tomography in the evaluation of patients with chest pain

Cardiac computed tomography in patients with symptomatic new-onset atrial fibrillation, rule-out acute coronary syndrome, but with intermediate pretest probability for coronary artery disease admitted to a chest pain unit

Background

Atrial fibrillation (AF) and coronary artery disease (CAD) may be encountered coincidently in a large portion of patients. However, data on coronary artery calcium burden in such patients are lacking. Thus, we sought to determine the value of cardiac computed tomography (CCT) in patients presenting with new-onset AF associated with an intermediate pretest probability for CAD admitted to a chest pain unit (CPU).

Methods

Calcium scores (CS) of 73 new-onset, symptomatic AF subjects without typical clinical, electrocardiographic, or laboratory signs of acute coronary syndrome (ACS) admitted to our CPU were analyzed. In addition, results from computed tomography angiography (CTA) were related to coronary angiography findings whenever available.

Results

Calcium scores of zero were found in 25%. Median Agatston score was 77 (interquartile range: 1–270) with gender- and territory-specific dispersal. CS scores above average were present in about 50%, high (> 400)-to-very high (> 1000) CS scores were found in 22%. Overall percentile ranking showed a relative accordance to the reference percentile distribution. Additional CTA was performed in 47%, revealing stenoses in 12%. Coronary angiography was performed in 22% and resulted in coronary intervention or surgical revascularization in 7%. On univariate analysis, CS > 50th percentile failed to serve as an independent determinant of significant stenosis during catheterization.

Conclusions

Within a CPU setting, relevant CAD was excluded or confirmed in almost 50%, the latter with a high proportion of coronary angiographies and subsequent coronary interventions, underlining the diagnostic value of CCT in symptomatic, non-ACS, new-onset AF patients when admitted to a CPU.

Cardiac Computed Tomography in Certified German Chest Pain Units

OBJECTIVE

The German Cardiac Society runs a nation-wide certification campaign for specialized chest pain units (CPUs). So far, cardiac computed tomography (CT) is not an integral part of such certification. The aim of our study was to analyze whether or not cardiac CT is nevertheless routinely used for further stratification in low-risk patients.

METHODS

For the time interval from January 2010 to April 2011, data were retrieved from the mandatory German CPU registry. Patients with and without cardiac CT during CPU index stay were compared.

RESULTS

Out of 5800 patients, 314 patients (5.4%) underwent cardiac CT during the index CPU stay. Unstable angina pectoris was the most common diagnosis when performing cardiac CT [34.4% vs. 17.7%; odds ratio (OR), 2.44; confidence interval (CI), 1.91-3.11; P < 0.001). Patients undergoing cardiac CT received significantly less often coronary angiography (31.8% vs. 54.8%; OR, 0.39; CI, 0.30-0.49; P < 0.001) or coronary revascularization (15.6% vs. 36.5%; OR, 0.32; CI, 0.23-0.46; P < 0.001). The use of cardiac CT did not prolong the length of stay in the CPU (20:48 vs. 20:25 h, P = 0.21).

CONCLUSIONS

Cardiac CT is underrepresented within the diagnostic work up in certified CPUs in Germany, although its use reduces unnecessary invasive diagnostics. The use of cardiac CT should be reconsidered during the next update of the CPU certification criteria.

Coronary artery calcium screening: current status and recommendations from the European Society of Cardiac Radiology and North American Society for Cardiovascular Imaging

Current guidelines and literature on screening for coronary artery calcium for cardiac risk assessment are reviewed for both general and special populations. It is shown that for both general and special populations a zero score excludes most clinically relevant coronary artery disease. The importance of standardization of coronary artery calcium measurements by multi-detector CT is discussed.

Diagnosis and Screening of Coronary Artery Disease

Diagnostic testing for CAD is aided by the calculation of the pretest probability using either the Diamond-Forrester score or the Morise score. Patients who have a low risk of CAD should not undergo testing. Exercise ECG testing should be reserved for patients who have pretest probabilities lower than 20%, because a negative test does not adequately reduce the posttest probability of significant CAD. For patients who are at intermediate risk, either nuclear perfusion imaging or stress echocardiography is an acceptable choice depending on local availability and practice. Due to its low specificity, CAC scoring is currently limited in its usefulness for the diagnosis of CAD in symptomatic patients. Currently, screening for CAD among patients at low risk should not extend beyond screening for traditional risk factors. Physicians should use the Framingham Risk Score to stratify patients into levels of 10-year risk for cardiac events. Due to its high rate of false positive tests and low sensitivity, exercise ECG is of limited value in screening. Among patients with higher levels of risk, in whom further risk stratification would be of use in making decisions about risk factor management, measurement of CAC either with EBCT or multidetector row CT scanning is a promising option, but more research is required before its use should become widespread. Measures of endothelial function are in development but lack data to support their widespread use currently.

Assessment of coronary arteries with CT

This article is designed to provide the reader information about the technical details of retrospective ECG-gated spiral 4SCT and its applications for the detection and quantification of coronary artery calcification, the detection of coronary artery stenoses, and the characterization of coronary atherosclerotic plaques.