Usefulness of routine use of multidetector coronary computed tomography in the "fast track" evaluation of patients with acute chest pain

Clinical applications of cardiac computed tomography: a consensus paper of the European Association of Cardiovascular Imaging-part I

Cardiac computed tomography (CT) was introduced in the late 1990's. Since then, an increasing body of evidence on its clinical applications has rapidly emerged. From an initial emphasis on its technical efficiency and diagnostic accuracy, research around cardiac CT has now evolved towards outcomes-based studies that provide information on prognosis, safety, and cost. Thanks to the strong and compelling data generated by large, randomized control trials, the scientific societies have endorsed cardiac CT as pivotal diagnostic test for the management of appropriately selected patients with acute and chronic coronary syndrome. This consensus document endorsed by the European Association of Cardiovascular Imaging is divided into two parts and aims to provide a summary of the current evidence and to give updated indications on the appropriate use of cardiac CT in different clinical scenarios. This first part focuses on the most established applications of cardiac CT from primary prevention in asymptomatic patients, to the evaluation of patients with chronic coronary syndrome, acute chest pain, and previous coronary revascularization.

Virtual (Computed) Fractional Flow Reserve: Future Role in Acute Coronary Syndromes

The current management of acute coronary syndromes (ACS) is with an invasive strategy to guide treatment. However, identifying the lesions which are physiologically significant can be challenging. Non-invasive imaging is generally not appropriate or timely in the acute setting, so the decision is generally based upon visual assessment of the angiogram, supplemented in a small minority by invasive pressure wire studies using fractional flow reserve (FFR) or related indices. Whilst pressure wire usage is slowly increasing, it is not feasible in many vessels, patients and situations. Limited evidence for the use of FFR in non-ST elevation (NSTE) ACS suggests a 25% change in management, compared with traditional assessment, with a shift from more to less extensive revascularisation. Virtual (computed) FFR (vFFR), which uses a 3D model of the coronary arteries constructed from the invasive angiogram, and application of the physical laws of fluid flow, has the potential to be used more widely in this situation. It is less invasive, fast and can be integrated into catheter laboratory software. For severe lesions, or mild disease, it is probably not required, but it could improve the management of moderate disease in 'real time' for patients with non-ST elevation acute coronary syndromes (NSTE-ACS), and in bystander disease in ST elevation myocardial infarction. Its practicability and impact in the acute setting need to be tested, but the underpinning science and potential benefits for rapid and streamlined decision-making are enticing.

The role of coronary CT angiography for acute chest pain in the era of high-sensitivity troponins

Accurate and efficient diagnostic triage for acute chest pain (ACP) remains one of the most challenging problems in the emergency department (ED). While the proportion of patients that present with myocardial infarction (MI), aortic dissection, or pulmonary embolism is relatively low, a missed diagnosis can be life threatening. Coronary computed tomography angiography (CCTA) has developed into a robust diagnostic tool in the triage of ACP over the past decade, with several trials showing that it can reliably identify patients at low risk of major adverse cardiovascular events, shorten the length of stay in the ED, and reduce cost associated with the triage of patients with undifferentiated chest pain. Recently, however, high-sensitivity troponin assays have been increasingly incorporated as a rapid and efficient diagnostic test in the triage of ACP due to their higher sensitivity and negative predictive value of myocardial infarction. As more EDs adopt high-sensitivity troponin assays into routine clinical practice, the role of CCTA will likely change. In this review, we provide an overview of CCTA and high-sensitivity troponins for evaluation of patients with suspected ACS in the ED. Moreover, we discuss the changing role of CCTA in the era of high-sensitivity troponins.

Cardiac CT in the Emergency Department: Contrasting Evidence from Registries and Randomized Controlled Trials

PURPOSE OF REVIEW

To compare outcomes between registries and randomized controlled trials of coronary computed tomographic angiography (CCTA)-based versus standard of care approaches to the initial evaluation of patients with acute chest pain.

RECENT FINDINGS

Randomized trials have demonstrated CCTA to be a safe and efficient tool for triage of low- to intermediate-risk patients presenting to the emergency department with chest pain. Recent studies demonstrate heterogeneous result using different standard of care approaches for evaluation of hard endpoints in comparison with standard evaluation. Also, there has been continued concern for increase in subsequent testing after coronary CTA. Although CCTA improves detection of coronary artery disease, it is uncertain if it will bring improvement of long-term health outcomes at this point of time. Careful analysis of the previous results and further investigation will be required to validate evaluation of hard endpoints.

Assessing Coronary Blood Flow Physiology in the Cardiac Catheterisation Laboratory

Background:

Contemporary management of coronary disease focuses on the treatment of stenoses in the major epicardial vessels. However, myocardial blood flow is known to be contingent on a range of factors in addition to the patency of the epicardial vessels. These include anatomical and physiological factors such as the extent of myocardium supplied by the vessel, systemic blood pres-sure, the natural variation in vascular tone in response to physiological needs which allows for coro-nary autoregulation and pathological factors such as the presence of downstream obstruction to flow due to disease of the small coronary vessels or myocardium. The assessment of clinical effectiveness and adequacy of coronary revascularisation requires the ability to comprehensively and accurately as-sess and measure myocardial perfusion.

Conclusion:

In this article, we review the current methods of evaluating coronary blood flow and my-ocardial perfusion in the cardiac catheterisation laboratory.

Clinical update. Computed Tomography — an Emerging Tool for Triple Rule-Out in the Emergency Department. A Review

New imaging tools have been developed in recent years to rapidly and accurately diagnose life-threatening diseases associated with high mortality rates, such as acute coronary syndromes, acute aortic dissection, or pulmonary embolism. The concept of using computed tomographic (CT) assessment in emergency settings is based on the possibility of excluding multiple acute pathologies within one scan. It can be used for patients complaining of acute chest pain of unclear etiology with the possible association of acute coronary dissection or pulmonary embolism, but only a low to moderate risk of developing an acute coronary syndrome. One of the benefits of this protocol is the possibility of decreasing the number of patients who are hospitalized for further investigations. The technique also allows the rapid triage of patients and the safe discharge of those who show negative results. The aim of this review is to summarize the current medical literature regarding the potential use of CT for the triple rule-out (TRO) of coronary etiologies.

Chest pain: coronary CT in the ER

Cardiac CT has developed into a robust clinical tool during the past 15 years. Of the fields in which the potential of cardiac CT has raised more interest is chest pain in acute settings. In fact, the possibility to exclude with high reliability obstructive coronary artery disease (CAD) in patients at low-to-intermediate risk is of great interest both from the clinical standpoint and from the management standpoint. Several other modalities, with or without imaging, have been used during the past decades in the settings of new onset chest pain or in acute chest pain for both diagnostic and prognostic assessment of CAD. Each one has advantages and disadvantages. Most imaging modalities also focus on inducible ischaemia to guide referral to invasive coronary angiography. The advent of cardiac CT has introduced a new practice diagnostic paradigm, being the most accurate non-invasive method for identification and exclusion of CAD. Furthermore, the detection of subclinical CAD and plaque imaging offer the opportunity to improve risk stratification. Moreover, recent advances of the latest generation CT scanners allow combining both anatomical and functional imaging by stress myocardial perfusion. The role of cardiac CT in acute settings is already important and will become progressively more important in the coming years.

Cardiac CT angiography for evaluation of acute chest pain

Chest pain is the second most common emergency department (ED) presentation in the United States. Cardiac computed tomography angiography (CCTA) now plays an important role in the evaluation of patients with suspected acute coronary syndrome in the ED setting. In this article, we review the available techniques focused on the use of CCTA to evaluate patients fosr coronary atherosclerosis for timely triage of acute chest pain.

Effect of Coronary Computed Tomography Angiography Disease Burden on the Incidence of Recurrent Chest Pain

Introduction. The purpose of this study is to investigate chest pain evaluations after initial coronary computed tomography angiography (CCTA) based upon coronary artery disease (CAD) burden. Methods. CCTA results of 1,518 patients were grouped based on the CCTA results into no CAD, nonobstructive CAD (<50% maximal diameter stenosis), or obstructive CAD (≥50% stenosis). Chest pain evaluation after initial CCTA and rates of major adverse cardiovascular events (MACE) defined as the incidence of all-cause mortality, nonfatal MI, ischemic stroke, and late revascularization (>90 days following CCTA) were evaluated. Results. MACE rates were higher with obstructive CAD compared to nonobstructive CAD and no CAD (8.9% versus 0.7%, P < 0.001; 8.9 versus 1.6%, P < 0.001). One hundred seventy-four patients (11.5%) underwent evaluation for chest pain after index CCTA with rates significantly higher with obstructive CAD compared to both nonobstructive CAD and no CAD (7.5% versus 13.9% versus 17.8%, P < 0.001). The incidence of repeat testing was more frequent in patients with obstructive CAD (no CAD 36.5% versus nonobstructive CAD 54.9% versus obstructive CAD 67.7%, P = 0.015). Conclusion. Absence of obstructive disease on CCTA is associated with lower rates of subsequent evaluations for chest pain and repeat testing with low MACE event rates over a 22-month followup.

Utility of coronary artery calcium scoring in the evaluation of patients with chest pain

Although coronary artery calcium (CAC) scoring has an established role in risk-stratifying asymptomatic patients at intermediate risk of coronary heart disease (CHD), its utility in the evaluation of patients with chest pain is uncertain. We conducted a literature review of articles investigating the utility of: (1) CAC scoring in elective patients with indeterminate chest pain symptoms, (2) CAC as a "gatekeeper" in the triage of patients presenting to the emergency department (ED) with chest pain, and (3) the cost-effectiveness of the use of CAC scoring in the ED. We also evaluated the predictive accuracy of the absence of CAC in a pooled analysis of applicable studies. Only studies evaluating patients classified as low or intermediate risk were included. Low to intermediate risk was established by Framingham risk scores, Thrombolysis in Myocardial Infarction scores, Diamond-Forrester classification, or by the absence of typical angina symptoms, ischemic electrocardiogram, positive cardiac biomarkers, or a prior history of CHD. In our pooled analysis, the presence of any CAC resulted in a high sensitivity (range 70%-100%) for predicting the presence of obstructive coronary disease among symptomatic patients subsequently referred for coronary angiography. More importantly, a CAC score of 0 in low- and intermediate-risk ED populations with chest pain had a high negative predictive value (99.4%) for CHD events over an average follow-up of 21 months. CAC scoring also seems cost-effective in this population. Although further research is needed, carefully selected ED patients with a normal electrocardiogram, normal cardiac biomarkers, and CAC = 0 may be considered for early discharge without further testing.

The role of non-invasive imaging in patients with suspected acute coronary syndrome

This article gives an overview of the role of imaging in the diagnosis and management of acute coronary syndrome.

Coronary CT angiography for acute chest pain triage: techniques for radiation exposure reduction; 128 vs. 64 multidetector CT

BACKGROUND

Coronary CT angiography (CCTA) is used daily in acute chest pain triage, although exposing patients to significant radiation dosage. CCTA using prospective ECG gating (PG CCTA) enables significant radiation reduction.

PURPOSE

To determine whether the routine use of 128 vs. 64 multidetector CT (MDCT) can increase the proportion of patients scanned using PG CCTA technique, lowering radiation exposure, without decreasing image quality.

MATERIAL AND METHODS

The study comprised 232 patients, 116 consecutive patients scanned using 128 MDCT (mean age 49 years, 79 men, BMI 28) and 116 consecutive patients (mean age 50 years, 75 men, BMI 28) which were scanned using 64 MDCT. PG CCTA was performed whenever technically permissible by each type of scanner: 64 MDCT = stable heart rate (HR) <60/min and weight <110 kg; 128 MDCT = stable HR < 70/min and weight <140 kg. All coronary segments were evaluated for image quality using a visual scale of 1-5. An estimated radiation dose was recorded.

RESULTS

PC CCTA was performed in 84% and 49% of the 128 and 64 MDCT groups, respectively (P < 0.0001). Average image quality score were 4.6 ± 0.3 and 4.7 ± 0.1 for the 128 and 64 MDCT, respectively (P = 0.08). The mean radiation dose exposure was 6.2 ± 4.8 mSv and 10.4 ± 7.5 mSv for the 128 and 64 MDCT, respectively (P = 0.008).

CONCLUSION

The 128 MDCT scanner enables utilization of PG CCTA technique in a greater proportion of patients, thereby decreasing the related radiation significantly, without hampering image quality.

Immediate computed tomography coronary angiography versus delayed outpatient stress testing for detecting coronary artery disease in emergency department patients with chest pain

Noninvasive testing for coronary artery disease (CAD) is warranted for symptomatic patients with intermediate pretest likelihood of CAD. Accomplishing testing in an emergency department (ED) environment is challenging. We compared two strategies of CAD testing in ED patients: immediate computed tomography coronary angiography (CTCA) versus delayed outpatient stress testing. We conducted a historical control cohort study comparing symptomatic ED patients without an acute coronary syndrome who warranted noninvasive CAD testing. Two cohorts (50 patients each) were defined by CAD testing strategy, immediate CTCA versus delayed stress testing. Outcomes were duration of ED stay, detection of CAD, and 3-month rates of readmission, myocardial infarction, (MI) or death. Median duration of stay was 417.5 minutes (interquartile range [IQR] 359.0-581.0) in the CT cohort and 400.0 minutes (IQR 338.0-471.0) in the control cohort (P = 0.53). CAD was detected in 14 CT cohort patients versus 1 in control (P = 0.0004), due to low follow-up in the control cohort (18 of 50, 36%). Obstructive CAD was diagnosed in 6 CT cohort patients versus 1 in control (P = 0.11). During 3 months of follow-up, four patients in each cohort were reevaluated in the ED for chest pain; no patients suffered MI or death. A strategy of immediate CTCA is superior to a delayed stress testing strategy for detecting CAD in ED patients with chest pain and prompting appropriate referrals for further management. Delayed stress testing was primarily ineffective due to low follow-up. Immediate CTCA can be used safely without altering the ED duration of stay.

Routine use of coronary computed tomography as initial diagnostic test for angina pectoris

BACKGROUND

Coronary computed tomography (CCT) detects coronary obstruction with high sensitivity and might be useful for diagnosis of angina pectoris.

AIM

In this pilot study, we sought to prospectively evaluate the performance of CCT as initial work up and determine the significance of this strategy according to the pretest likelihood of having coronary artery disease (CAD).

METHODS

One hundred and eighty patients with chest discomfort and suspected angina were prospectively referred for CCT with a 64-slice CT scan. Invasive coronary angiography (ICA) was performed on the basis of CCT findings (stenosis>50%). Patients were classified into tertiles according to estimated pretest probability of obstructive CAD using the Duke Clinical Score (low, intermediate and high). Strategy failure was defined as unnecessary ICA or major adverse cardiac event (MACE) within 6 months in patients without significant stenosis by CCT.

RESULTS

Pretest probability for CAD was 53 ± 29%. Significant stenosis was detected by CCT in 51 patients; 47 (26%) underwent ICA. Sixteen strategy failures were reported: 15 patients (10%) were referred for ICA that did not confirm significant coronary stenosis and one MACE occurred in a patient without significant stenosis by CCT. Strategy failures were 8% in low-probability, 1.7% in intermediate-probability and 15% in high-probability patients (P=0.03).

CONCLUSIONS

CCT as an initial step for angina diagnosis is most effective in patients with an intermediate probability of CAD. In patients with low or high likelihood, it is associated with a high rate of unnecessary ICA but not with adverse events.

Noninvasive anatomical coronary artery imaging versus myocardial perfusion imaging: which confers superior diagnostic and prognostic information?

Myocardial perfusion imaging (MPI) has been a valuable diagnostic and prognosticating tool for decades, but recently it has been challenged by the growing evidence about either comparable or superior diagnostic and prognostic value of computed tomography (CT)-based anatomical imaging modalities. Although there are some studies suggesting synergy and potential for combined use of these modalities to better diagnose coronary artery disease (CAD), it is important to evaluate these approaches separately, given cost and other restraints. This review compares the noninvasive anatomical imaging modalities of coronary artery calcium scoring and coronary CT angiography to the functional assessment modality of MPI in the diagnosis and prognostication of significant CAD in symptomatic patients. A large number of studies investigating this subject are analyzed with a critical look on the evidence, underlying the strengths and limitations. Although the overall findings of the presented studies are favoring the use of CT-based anatomical imaging modalities over MPI in the diagnosis and prognosticating of CAD, the lack of a high number of large- scale, multicenter randomized controlled studies limits the generalizability of this early evidence. Further studies comparing the short- and long-term clinical outcomes and cost-effectiveness of these tests are required to determine their optimal role in the management of symptomatic patients with suspected CAD.