Relation of plaque characteristics defined by coronary computed tomographic angiography to ST-segment depression and impaired functional capacity during exercise treadmill testing in patients suspected of having coronary heart disease

Comparison of Exercise Treadmill Testing With Cardiac Computed Tomography Angiography Among Patients Presenting to the Emergency Room With Chest Pain

Background—

The aims of our study were to (1) examine how data from exercise treadmill testing (ETT) can identify patients who have coronary plaque or stenosis, using CT angiography (CTA) as the reference standard, and (2) identify patient characteristics that may be used in selecting ETT versus CTA.

Methods and Results—

The Rule Out Myocardial Infarction Using Computer-Assisted Tomography (ROMICAT) trial was an observational cohort study of acute chest pain patients presenting to the emergency department with normal initial troponin and a nonischemic ECG. Univariate and multivariable analyses were performed to assess the relationship of baseline clinical data and ETT parameters with coronary plaque and stenosis on CTA. Of the 220 patients who had ETT (mean age, 51 years; 63% men), 21 (10%) had positive results. A positive ETT had a sensitivity of 30% and specificity of 93% to detect >50% stenosis. The sensitivity increased to 83% after excluding uninterpretable segments and evaluating the ability to detect a >70% stenosis. Predictors of plaque included older age, male sex, diabetes, hypertension, hyperlipidemia, lower functional capacity, and a lower Duke Treadmill Score. Both a positive ETT and a low Duke Treadmill Score were significant univariate and multivariable predictors of stenosis >50% on CTA Whereas the prevalence of stenosis by CTA was greater among patients with more risk factors, coronary stenosis was not present among men <40 years old or women <50 years old or individuals who achieved at least 13 metabolic equivalents on ETT.

Conclusions—

Among low- to intermediate-risk patients with acute chest pain, a positive ETT has a limited sensitivity but high specificity for the detection of >50% stenosis by CTA. Although patients with a high number of clinical risk factors are more likely to have obstructive coronary artery disease, those who are young or who would be expected to have a very high exercise capacity are unlikely to have coronary stenosis and therefore may benefit from initial ETT testing instead of CTA.

Influence of coronary computed tomography-angiography on patient management

AIM

To evaluate how coronary computed tomography-angiography (CCTA) altered the management and treatment of patients with suspected coronary artery disease (CAD).

METHODS

During 2009, we studied 792 consecutive patients with suspected CAD. CCTA was performed in all patients using a 64-slice dual-source CT scanner and standard scanning protocols.

RESULTS

After CCTA, obstructive CAD was excluded in 666 patients. During the 12-month clinical follow-up, 98.6% of these patients were free of major adverse cardiac events. Also, the indication for cardiac catheterization (CC) was revoked in 77.2% of patients. It was also revoked in all patients with low Morise pre-test risk, 80.7% with intermediate risk, and 72.6% with high risk. Medical therapy was changed in 54.7% of patients with confirmed CAD.

CONCLUSION

CCTA can reliably exclude significant CAD not only in patients with low and moderate risk, but also in those with high risk. It can also reliably replace CC in the majority of elective patients regardless of risk stratification. It can also be useful in risk reclassification and optimization of medical therapy in patients with CAD.

Utility of nonspecific resting electrocardiographic features for detection of coronary artery stenosis by computed tomography in acute chest pain patients: from the ROMICAT trial

Twelve-lead surface electrocardiography (ECG) and computed tomography (CT) are used to evaluate for myocardial ischemia and coronary artery disease (CAD), respectively. We aimed to determine features on resting ECG that predict coronary artery stenosis by cardiac CT. In 309 acute chest pain patients, we compared the initial triage resting ECG to contrast-enhanced 64-slice cardiac CT angiography. We assessed for 6 quantitative (QT interval, QTc interval, QTc > 440 ms, gender-specific QTc, QT dispersion and QRS duration) and 4 qualitative ECG parameters (ST depression >0.05 to ≤0.1 mV, T wave inversion ≥0.1 mV, T wave flattening, and any T wave abnormalities) and for the presence of coronary stenosis by CT (>50% luminal narrowing). Specificities of these ECG parameters were excellent (83.6-97.0%) while sensitivities were poor (12.2-29.3%). For coronary stenosis detection, the ECG features with the greatest performance were the presence of ST depression (positive likelihood ratio [LR+] 4.09) and T wave inversion (LR+ 4.58). In multivariable analyses, the risk for coronary stenosis increased by 33-41% for every 20 ms prolongation of the QTc interval after adjusting for age, gender, and cardiac risk factors or adjustment for Framingham risk score. Similarly, there was an increase of fourfold with the presence of ST depression >0.05 to ≤0.1 mV or T wave inversion ≥0.1 mV. In acute chest pain patients, resting ECG features of QTc interval prolongation, mild ST depression, and T wave inversion are independently associated with the presence of CT coronary stenosis and their presence suggests an increase risk of CAD.

Nonobstructive coronary artery disease as detected by 64-detector row cardiac computed tomographic angiography is associated with increased left ventricular mass

BACKGROUND

Cardiac computed tomographic angiography (CCTA) permits simultaneous assessment of coronary artery disease (CAD) and left ventricular mass (LVM). While increased LVM predicts mortality and is associated with obstructive CAD, the relationship of LVM with non-obstructive CAD is unknown.

METHODS

We evaluated 212 consecutive patients undergoing 64-detector row CCTA at 2 sites without evident cardiovascular disease or obstructive (≥70%) CAD by CCTA. LVM was measured by CCTA using Simpson's method of disks and indexed to body surface area (LVMI) and height to the allometric power of 2.7(LVM/ht2.7). CCTAs were evaluated by scoring a modified AHA 16-segment coronary artery model for none = 0 (0% stenosis), mild = 1 (1-49% stenosis) or moderate = 2 (50-69% stenosis). Overall CAD plaque burden was estimated by summing scores across all segments for a segment stenosis score (SSS, max = 32).

RESULTS

The mean age was 53.3 ± 12.8 with 52% female, 48% hypertensive, and 7.4% diabetic. The mean LVM was 109 ± 32.5 g; 58.5% had any coronary artery plaque. In multivariable linear regression, SSS was significantly associated with increased LVM, LVMI and LVM/ht2.7. LVM increased by 2.0 g for every 1-point increase in SSS (95% CI 0.06-3.4, p = 0.006). Agatston scores provided no additional predictive value for increased LVM above and beyond SSS.

CONCLUSION

Non-obstructive CAD visualized by CCTA is associated with increased LVM independent of effects of clinical risk factors and calcium scoring. Whether addition of LVM to stenosis assessment in patients undergoing CCTA enhances risk prediction of future CAD events warrants investigation.

Assessment of the relationship between stenosis severity and distribution of coronary artery stenoses on multislice computed tomographic angiography and myocardial ischemia detected by single photon emission computed tomography

BACKGROUND

The relationship between luminal stenosis measured by coronary CT angiography (CCTA) and severity of stress-induced ischemia seen on single photon emission computed tomographic myocardial perfusion imaging (SPECT-MPI) is not clearly defined. We sought to evaluate the relationship between stenosis severity assessed by CCTA and ischemia on SPECT-MPI.

METHODS AND RESULTS

ECG-gated CCTA (64 slice dual source CT) and SPECT-MPI were performed within 6 months in 292 patients (ages 26-91, 73% male) with no prior history of coronary artery disease. Maximal coronary luminal narrowing, graded as 0, ≥25%, 50%, 70%, or 90% visual diameter reduction, was consensually assessed by two expert readers. Perfusion defect on SPECT-MPI was assessed by computer-assisted visual interpretation by an expert reader using the standard 17 segment, 5 point-scoring model (stress perfusion defect of ≥5% = abnormal). By SPECT-MPI, abnormal perfusion was seen in 46/292 patients. With increasing stenosis severity, positive predictive value (PPV) increased (42%, 51%, and 74%, P = .01) and negative predictive value was relatively unchanged (97%, 95%, and 91%) in detecting perfusion abnormalities on SPECT-MPI. In a receiver operator curve analysis, stenosis of 50% and 70% were equally effective in differentiating between the presence and absence of ischemia. In a multivariate analysis that included stenosis severity, multivessel disease, plaque composition, and presence of serial stenoses in a coronary artery, the strongest predictors of ischemia were stenosis of 50-89%, odds ratio (OR) 7.31, P = .001, stenosis ≥90%, OR 34.05, P = .0001, and serial stenosis ≥50% OR of 3.55, P = .006.

CONCLUSIONS

The PPV of CCTA for ischemia by SPECT-MPI rises as stenosis severity increases. Luminal stenosis ≥90% on CCTA strongly predicts ischemia, while <50% stenosis strongly predicts the absence of ischemia. Serial stenosis of ≥50% in a vessel may offer incremental value in addition to stenosis severity in predicting ischemia.

Interobserver variations of plaque severity score and segment stenosis score in coronary arteries using 64 slice multidetector computed tomography: a substudy of the ACCURACY trial

BACKGROUND

Assessing the severity of coronary plaque for the risk stratification and management of coronary artery disease is important. Multidetector computed tomography has been shown to be a useful tool to measure coronary plaque; however, interreader variability is a concern.

OBJECTIVE

We measured interobserver variations of plaque severity score (PSS) and segment stenosis score (SSS) as measured by the total plaque severity score (TPS) and total segment stenosis score (TSS).

METHODS

Cardiac CT scans (n = 221) of the ACCURACY trial were interpreted by 3 different readers blinded to patient characteristics. PSS (mild, 1; moderate, 2; and severe, 3) and SSS (stenosis 1%-29%, 1; 30%-49%, 2; 50%-69%, 3; and ≥70%, 4) were calculated with the 15-segment American Heart Association model. TPS and TSS were determined by summing the segments for each interpreter. TPS and TSS were compared for correlation and variation among any 2 of the 3 readers.

RESULTS

A highly significant correlation was observed among any 2 of the 3 readers for both TPS and TSS. For TPS, the r = 0.91, 0.93, 0.94 (P < 0.001) for A vs B, B vs C, A vs C, respectively, and for TSS, r = 0.91, 0.92, 0.93 (P < 0.001) for A vs B, B vs C, A vs C, respectively. On Bland Altman plot, the mean difference between the scores of any 2 readers was 3.33 ± 3.93, 1.65 ± 2.88, and 1.68 ± 2.92 for TPS and 4.19 ± 4.73, 2.54 ± 4.02, and 1.65 ± 3.18 for TSS.

CONCLUSION

Semiquantitative measures of coronary plaque burden, including the TPS and TSS, can be determined with a high degree of interobserver agreement, suggesting their potential role as tools to aid in the assessment of coronary heart disease.

The present state of coronary computed tomography angiography a process in evolution

In the past 5 years since the introduction of 64-detector row cardiac computed tomography angiography (CCTA), there has been an exponential growth in the quantity of scientific evidence to support the feasibility of its use in the clinical evaluation of individuals with suspected coronary artery disease (CAD). Since then, there has been considerable debate as to where CCTA precisely fits in the algorithm of evaluation of individuals with suspected CAD. Proponents of CCTA contend that the quality and scope of the available evidence to date support the replacement of conventional methods of CAD evaluation by CCTA, whereas critics assert that clinical use of CCTA is not yet adequately proven and should be restricted, if used at all. Coincident with the scientific debate underlying the clinical utility of CCTA, there has developed a perception by many that the rate of growth in cardiac imaging is disproportionately high and unsustainable. In this respect, all noninvasive imaging modalities and, in particular, more newly introduced ones, have undergone a higher level of scrutiny for demonstration of clinical and economic effectiveness. We herein describe the latest available published evidence supporting the potential clinical and cost efficiency of CCTA, drawing attention not only to the significance but also the limitations of such studies. These points may trigger discussion as to what future studies will be both necessary and feasible for determining the exact role of CCTA in the workup of patients with suspected CAD.

Relation of coronary artery plaque location to extent of coronary artery disease studied by computed tomographic angiography

BACKGROUND

Distal coronary artery disease (CAD) is less amenable to surgery or stenting compared with proximal disease. However, little is known about the epidemiology of distal versus proximal CAD.

METHODS

We determined the prevalence and factors associated with proximal, mid, and distally located plaque in the left anterior descending, left circumflex, and right coronary arteries in 418 subjects without prior CAD history who underwent coronary computed tomographic angiography for symptoms or stress test results. Clinical characteristics and coronary artery calcium (CAC) scores were also determined.

RESULTS

Most subjects (88%) had plaque, but only 18% of plaques were associated with stenosis >50%. In subjects with single-vessel plaque, only 7% had distal plaque, whereas 75% had proximal plaque. With 3-vessel plaque, 70% had distal and 100% had proximal plaques. Of subjects with a single location of plaque along a vessel, most had proximal plaque (69%); isolated distal-vessel plaque was rare (2%). Distal plaque was dominantly found in association with both proximal and mid plaque (88%). After multivariable adjustment for demographics, traditional, and nontraditional risk factors, both increasing number of vessels with plaque and clinically significant CAC scores were independently associated with higher odds of distal plaque, whereas associations of traditional risk factors were weaker. Distal plaque was independently associated with stenosis > 50%.

CONCLUSION

These data support the concept that early lesions are most often proximal and that CAC scoring may be a poor screening tool for detecting proximal disease. Furthermore, distal lesions are more associated with advanced disease than with traditional cardiovascular risk factors.

The prognostic value of cardiac computed tomographic angiography

With advancements in temporal and spatial resolution, CT has excellent diagnostic characteristics for non-invasive evaluation of coronary artery disease in appropriate patients. Nevertheless, clinical usefulness of diagnostic testing requires not only high diagnostic accuracy but also risk stratification for patient management. Current guidelines for risk stratification of patients with coronary artery disease rely primarily upon functional testing; alternatively, anatomic risk stratification may also be performed with invasive coronary angiography. This article reviews current and emerging concepts in the prognostic value of cardiac CT angiography.

Risk assessment and predictive value of coronary artery disease testing

This review highlights and compares risk assessment, predictive accuracy, and economic outcomes for 3 commonly applied cardiac imaging procedures: stress myocardial perfusion SPECT or PET and coronary CT angiography (CCTA). This review highlights an expansive evidence base for stress myocardial perfusion imaging and reveals a decided advantage for higher-risk patients, notably those who have established coronary artery disease (CAD). It is likely that the use of CCTA will continue to expand, particularly for patients with more atypical symptoms and patients with a lower likelihood of CAD. Despite a high level of evidence, comparative research is not available across modalities that could definitively drive utilization of cardiac imaging modalities.