Significant limitations exist for traditional noninvasive cardiac imaging with regard to equivocal or indeterminate findings that result in repetitive testing or unnecessary referral to invasive coronary angiography (ICA). Recent hardware and software advances in multislice computed tomography angiography have achieved high spatial and temporal resolution to allow accurate noninvasive assessment of coronary arteries. This poses a paradigm shift in management of patients with suspected coronary artery disease (CAD).
Multicenter studies showed that coronary computed tomography angiography (CCTA) has a very high diagnostic accuracy, and, in particular, a very high negative predictive value (>98%) in detecting coronary stenosis when compared with ICA. In addition to its diagnostic ability, recent evidence-based outcome data have also validated the value of CCTA in predicting cardiac events. Absence of CAD on CCTA conveys excellent prognosis, whereas increasing disease severity and extent are associated with worsening outcome. Furthermore, CCTA allows comprehensive assessment of coronary stenosis, plaque burden, left ventricular morphology, function, perfusion and viability. One concern with CCTA is the issue of ionizing radiation exposure. Recent technical progress allows dramatic reduction of radiation dose. The newest generation scanner is capable of producing CCTA of diagnostic quality with a dose of less than 1 mSv. A multisociety guideline for appropriate clinical indications for cardiac computed tomography was recently published.
When used appropriately, CCTA has been established as a valid noninvasive imaging alternative to ICA in selected patients at low to intermediate risk of CAD.
[Show abstract][Hide abstract] ABSTRACT: To investigate the added value of myocardial perfusion scintigraphy imaging (MPI) in consecutive patients with suspected coronary artery disease (CAD) and a recent, normal exercise electrocardiography (ECG).
This study was a retrospective analysis of consecutive patients referred for MPI during a 2-year period from 2006-2007 at one clinic. All eligible patients were suspected of suffering from CAD, and had performed a satisfactory bicycle exercise test (i.e., peak heart rate > 85% of the expected, age-predicted maximum) within 6 mo of referral, their exercise ECG was had no signs of ischemia, there was no exercise-limiting angina, and no cardiac events occurred between the exercise test and referral. The patients subsequently underwent a standard 2-d, stress-rest exercise MPI. Ischemia was defined based on visual scoring supported by quantitative segmental analysis (i.e., sum of stress score > 3). The results of cardiac catheterization were analyzed, and clinical follow up was performed by review of electronic medical files.
A total of 56 patients fulfilled the eligibility criteria. Most patients had a low or intermediate ATPIII pre-test risk of CAD (6 patients had a high pre-test risk). The referral exercise test showed a mean Duke score of 5 (range: 2 to 11), which translated to a low post-exercise risk in 66% and intermediate risk in 34%. A total of seven patients were reported with ischemia by MPI. Three of these patients had high ATPIII pre-test risk scores. Six of these seven patients underwent cardiac catheterization, which showed significant stenosis in one patient with a high pre-test risk of CAD, and indeterminate lesions in three patients (two of whom had high pre-test risk scores). With MPI as a gate keeper for catheterization, no significant, epicardial stenosis was observed in any of the 50 patients (0%, 95% confidence interval 0.0 to 7.1) with low to intermediate pre-test risk of CAD and a negative exercise test. No cardiac events occurred in any patients within a median follow up period of > 1200 d.
The added diagnostic value of MPI in patients with low or intermediate risk of CAD and a recent, normal exercise test is marginal.
World Journal of Cardiology (WJC) 03/2013; 5(3):54-9. DOI:10.4330/wjc.v5.i3.54 · 2.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the United States, chest pain is the second leading reason for patients to present to an emergency department (ED). Previously, those patients suspected to have acute coronary syndrome were monitored for 24 hours to determine the presence of serum biomarkers consistent with myocardial injury. However, more recently, imaging has been used to more efficiently triage these individuals and even discharge them directly from the ED. There are multiple cardiac imaging modalities; however, cardiac computed tomography now plays a significant role in the evaluation of patients with suspected acute coronary syndrome who present to the ED. In this review, we discuss the available state-of-the-art techniques for evaluating this cohort of patients, including clinical evaluation, serum biomarkers, and imaging options. Further, we analyze in detail evidence for the use of coronary computed tomography angiography to determine whether these patients can safely be discharged from the ED. Finally, we review some of the related future techniques that may become part of the accepted clinical management of these patients in the future.
[Show abstract][Hide abstract] ABSTRACT: The radiation risk of patients undergoing invasive cardiology remains considerable and includes skin injuries and cancer. To date, submillisievert coronary angiography has not been considered feasible.
In 2011, we compared results from 100 consecutive patients undergoing elective coronary angiography using the latest-generation flat-panel angiography system (FPS) with results from examinations by the same operator using 106 historic controls with a conventional image-intensifier system (IIS) that was new in 2002.
The median patient exposure parameters were measured as follows: dose-area product (DAP) associated with radiographic cine acquisitions (DAP(R)) and fluoroscopy (DAP(F)) scenes, radiographic frames and runs, and cumulative exposure times for radiography and fluoroscopy. On the FPS as compared to the traditional IIS, radiographic detector entrance dose levels were reduced from 164 to 80 nGy/frame and pulse rates were lowered from 12.5/s to 7.5/s during radiography and from 25/s to 4/s during fluoroscopy. The cardiologist's performance patterns remained comparable over the years: fluoroscopy time was constant and radiography time even slightly increased. Overall patient DAP decreased from 7.0 to 2.4 Gy × cm(2); DAP(R), from 4.2 to 1.7 Gy × cm(2); and DAP(F), from 2.8 to 0.6 Gy × cm(2). Time-adjusted DAP(R)/s decreased from 436 to 130 mGy × cm(2) and DAP(F)/s, from 21.6 to 4.4 mGy × cm(2). Cumulative patient skin dose with the FPS amounted to 67 mGy, and the median (interquartile range) of effective dose was 0.5 (0.3 … 0.7) mSv.
Consistent application of radiation-reducing techniques with the latest-generation flat-panel systems enables submillisievert coronary angiography in invasive cardiology.
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