Baseline stress myocardial perfusion imaging results and outcomes in patients with stable ischemic heart disease randomized to optimal medical therapy with or without percutaneous coronary intervention

BACKGROUND

The COURAGE trial reported similar clinical outcomes for patients with stable ischemic heart disease (SIHD) receiving optimal medical therapy (OMT) with or without percutaneous coronary intervention (PCI). The current post hoc substudy analysis examined the relationship between baseline stress myocardial ischemia and clinical outcomes based on randomized treatment assignment.

METHODS

A total of 1,381 randomized patients (OMT n = 699, PCI + OMT n = 682) underwent baseline stress myocardial perfusion single-photon emission computed tomographic imaging. Site investigators interpreted the extent of ischemia by the number of ischemic segments using a 6-segment myocardial model. Patients were divided into those with no to mild (<3 ischemic segments) and moderate to severe ischemia (≥ 3 ischemic segments). Cox proportional hazards models were calculated to assess time to the primary end point of death or myocardial infarction.

RESULTS

At baseline, moderate to severe ischemia occurred in more than one-quarter of patients (n = 468), and the incidence was comparable in both treatment groups (P = .36). The primary end point, death or myocardial infarction, was similar in the OMT and PCI + OMT treatment groups for no to mild (18% and 19%, P = .92) and moderate to severe ischemia (19% and 22%, P = .53, interaction P value = .65). There was no gradient increase in events for the overall cohort with the extent of ischemia.

CONCLUSIONS

From the COURAGE trial post hoc substudy, the extent of site-defined ischemia did not predict adverse events and did not alter treatment effectiveness. Currently, evidence supports equipoise as to whether the extent and severity of ischemia impact on therapeutic effectiveness.

Association of left ventricular mechanical dyssynchrony with survival benefit from revascularization: a study of gated positron emission tomography in patients with ischemic LV dysfunction and narrow QRS

PURPOSE

LV mechanical dyssynchrony (LVMD) is a risk marker in narrow QRS cardiomyopathy, but its association with treatment outcome is not well defined. We determined the incremental prognostic value of LVMD in ischemic cardiomyopathy, and assessed its interaction with scar, myocardium in jeopardy and subsequent revascularization.

METHODS

Stress and rest (82)Rb gated PET were performed in 486 consecutive patients (66 ± 11 years of age, 82 % men, LV ejection fraction 26 ± 6 %) with ischemic cardiomyopathy and QRS <120 ms. LVMD was determined as the standard deviation (SD) of the regional time to minimum volume on phase analysis of the gated PET scan. A propensity score was determined to adjust for nonrandomized referral after imaging to coronary artery bypass grafting (CABG). In a Cox proportional hazards model used to determine the association between measures of LVMD and survival time, CABG was included as a time-dependent covariate and the use of an implantable cardiac defibrillator (ICD) after imaging was modeled as a stratification factor.

RESULTS

Over 1.9 ± 1.4 years, 96 patients (20 %) underwent CABG and 108 (22 %) died. LVMD was a predictor of mortality (HR 1.16. 95 % CI 1.03;1.30, per 10° increase in phase SD, p = 0.02) after adjusting for baseline covariates, prior ICD use, the use of postimaging CABG, and other imaging data. There was a significant interaction between phase SD and CABG. Nested Cox models showed that LVMD carried prognostic information incremental to clinical variables, ejection fraction and CABG.

CONCLUSION

LVMD is an independent predictor of all-cause mortality in ischemic cardiomyopathy, and may identify patients with a differential survival benefit from CABG versus medical therapy.

Abstract 101: Is The Question Of Viability Imaging In Patients With Left Ventricular Dysfunction Relevant? Predictors Of Post-viability Imaging Referral To Revascularization

Background . In light of the recent STICH trial results, the clinical practice of viability imaging in patients (pts) with reduced left ventricular (LV) function has been called to question. Whether measures of hibernating myocardium alter pt management is unknown. We explored the impact of the results of cardiac positron emission tomography (PET) perfusion and viability imaging on short-term referral to revascularization.

Methods . We identified 586 consecutive patients with LV ejection fraction (EF) <50% who underwent Rb-82 dipyridamole stress/rest perfusion imaging with fluorodeoxyglucose (FDG) PET between March, 2006 and May, 2009. Automated quantitative software with user defined limits was used to determine the amount of myocardium that was scar, ischemic, or hibernating based on these results. Early revascularization (EREV) was performed within 90 days of PET in 198 patients (34%). Multiple logistic regression was used to model the association between the results of PET imaging and EREV after adjusting for potential confounders.

Results . Overall, pts were 65±12 years, 23% female, with mean LVEF 31±12%. Expressed as %total myocardium, PET results revealed 6.0±8.1% scar, 9.1±8.5% ischemia, and 14.7%±11.6% hibernation (total defect size 29.8±16.6%). Logistic regression revealed that after adjusting for pt age, sex, prior MI, BMI, diabetes, beta-blocker use, race, residence location, prior REV, chest pain, and LV end-diastolic volumes, ischemia was the single most powerful predictor of EREV [adjusted odds ratio (OR) and 95%CI: 2.6 (2.0-3.3) per 10% ischemia], while hibernation was not a predictor of EREV (p=0.77). The presence of scar reduced EREV [0.48 (0.34-0.66) per 10% scar].

Conclusion. Although assessment of ischemia and hibernation is often considered to be a standard part of the evaluation of pts with LV dysfunction, hibernating myocardium extent measured by cardiac PET does not influence subsequent referral to revascularization.

Abstract 107: Predictors and Frequency of ICD Implantation for Primary Prevention in ICD Eligible Patients: Results from a Prospective Multicenter Registry

Background . The use of implantable cardiac defibrillators has been associated with improved survival in several well-defined patient (pt) subsets. Its utilization for primary prevention in eligible pts, however, is unclear. We sought to examine the frequency of ICD implantation (ICD-IMP) for primary prevention in a cohort prospectively enrolled in a prospective, multicenter registry of ICD candidates.

Methods . We identified 961 pts enrolled in the AdreView Myocardial Imaging for Risk Evaluation in Heart Failure (ADMIRE-HF) study, a prospective, multicenter study evaluating the prognostic usefulness of 123I-mIBG scintigraphy in a heart failure population. Inclusion criteria limited patients to those meeting guideline criteria for ICD implantation; these criteria included left ventricular ejection fraction ≤35% and New York Heart Association functional class II-III. We excluded pts with an ICD at the time of enrollment, leaving a study cohort of 934 patients. Pts were followed up for 24 months after enrollment. Pts undergoing ICD-IMP after enrollment for secondary prevention were censored at the time of intervention. The association between ICD-IMP utilization and demographic, clinical, laboratory, and imaging data was examined using Cox proportional hazards analysis (CPH).

Results . Of 934 pts, 196 (21%) were referred for ICD-IMP over a mean follow-up of 612±242 days. Implantations occurred 167±164 days after enrollment. Patients referred for ICD were younger (61±12 vs. 63±12), but did not differ with respect to proportion female (17% vs. 21%), African-American race (12% vs. 15%), diabetics (37% vs. 36%) (All p=NS). The frequency of ICD-IMP did not differ as a function of age, race, sex, LVEF, or imaging result (All p=NS). CPH revealed that a model including age, race, sex, diabetes, smoking, BMI, NYHA class, hypertension, heart failure etiology, and prior MI identified none of these as predictive of ICD-IMP.

Conclusion: This analysis of prospective registry data reveals that in patients who are guideline-defined candidates for ICD-IMP, only about one in five receive an ICD over a two year follow-up interval. Multivariable modeling failed to identify any factor associated with ICD use.

Abstract 279: The Impact of Heart Failure on Depression and Quality of Life is Greater in Men than Women

Background. Patients (pts) diagnosed with congestive heart failure (HF) have been reported to have more frequent depression and worsened health related quality of life (HRQOL). Although depression is more common in women than men in this condition, the impact of HF on depression and HRQOL in men versus women is unclear. We sought to examine the relationship between pt sex, HF diagnosis, and pt-perceived depression and HRQOL.

Methods. Depression (PHQ-9) and HRQOL (EQ5D) data were collected using tablet computers from pts presenting for routine outpatient cardiovascular assessment at our institution between November, 2010 and December, 2011. Demographic, clinical, and historical data was collected as per routine. We examined the association of pt sex and clinical diagnosis of HF with instrument results after adjusting for potential confounding information using mutliple linear regression.

Results. Of 3046 pts (age 61±15), 39% were female and 8.7% were diagnosed with HF. Overall, PHQ-9 was greater, and minor or major depression (PHQ-9≥10) was more frequent, in women than men (4.6±4.6 vs. 3.3±4.4; 14.0% vs. 8.9%, both p<0.05) and in HF pts than pts without HF (5.9±5.6 vs. 3.6±4.3, 22.0% versus 9.6%; both p<0.05). Similarly, HRQOL was worse in women than men (EQ-5D 0.80±0.18 vs. 0.87±0.16; p<0.01) and in HF pts than no HF (EQ-5D 0.76±0.18 vs. 0.85±0.17; p<0.01). However, the difference in PHQ-9 between pts with versus without HF was greater in men (6.23±6.06 vs. 3.02±4.06, p<0.01) than women (5.43±4.85 vs. 4.55±4.58, p=0.09). After adjusting for cardiovascular diagnoses, comorbidities, clinical and demographic data, multivariable modeling of PHQ-9 revealed a significant interaction between pt sex and HF diagnosis (p=0.001; see Figure) such that women had greater PHQ-9 scores compared to men without HF, but in the setting of HF, mens' PHQ-9 scores were greater. Modeling of EQ-5D also revealed that after risk-adjustment an interaction between HF diagnosis and sex was present with a similar pattern of findings.

Conclusion. Although depression is more frequent and severe in women compared to men, and in pts with versus without HF, HF appears to impact depression severity more in men compared to women.

Nomograms for estimating coronary artery disease prognosis with gated stress myocardial perfusion SPECT

BACKGROUND

Nomograms can be useful tools for estimating coronary artery disease (CAD) risk. We sought to devise risk-based nomograms for stress myocardial perfusion SPECT to include measures of % ischemic myocardium and left ventricular function.

METHODS

A total of 4,575 patients were consecutively and prospectively enrolled in the Myoview Prognosis Registry. Multivariable Cox proportional hazards model were employed to estimate CAD death or MI. Nomograms were devised from the results of the Cox models.

RESULTS

CAD death or MI rates worsened in a gradient manner by the % ischemic myocardium. Higher risk patients were those with a rest and/or post-stress LVEF ≤ 45%. A nomogram was developed to estimate 2-year CAD death or MI-free survival for exercising and pharmacologic stress patients by their post-stress LVEF and % ischemic myocardium MPS results. Patients undergoing pharmacologic stress with a rest and/or post-stress LVEF ≤ 45% with high risk ischemic findings had the lowest CAD death or MI event-free survival. For exercising patients with a preserved resting LVEF > 45%, 2-year CAD death or MI event-free survival ranged from 99.4% to 89% for 0% to ≥20% ischemic myocardium. Those at highest risk included patients undergoing pharmacologic stress with depressed LVEF. For pharmacologic stress patients with a resting LVEF ≤45%, 2-year CAD death or MI event-free survival ranged from 89% to 48% for 0% to ≥20% ischemic myocardium. For pharmacologic stress patients with a post-stress LVEF ≤ 45%, 2-year CAD death or MI event-free survival ranged from 88% to 46% for 0% to ≥20% ischemic myocardium. A validation cohort revealed moderate-strong correlation between observed and predicted survival (r = 0.71). Average discordance between observed and predicted survival was ≤2% but was greater for higher risk patients with lower predicted survival estimates.

CONCLUSIONS

Risk-based nomograms estimating important CAD outcomes may serve as a clinically useful tool to target therapeutic intervention for high risk patient subsets.

Is cardiac catheterization necessary before initial management of patients with stable ischemic heart disease? Results from a Web-based survey of cardiologists

BACKGROUND

It is unknown whether preconceived beliefs regarding the need for cardiac catheterization and revascularization in patients with stable ischemic heart disease (SIHD) would preclude a study randomizing patients with significant ischemia to a conservative strategy. Given the widespread practice of performing revascularization in patients with SIHD, we assessed the feasibility of conducting a randomized trial comparing initial invasive and conservative strategies in patients with SIHD and moderate or severe ischemia.

METHODS

An online survey to cardiologists queried their willingness to enroll a sample patient with frequent stable angina, >10% myocardial ischemia, and normal ejection fraction into a randomized trial with a 50% chance of being conservatively managed without cardiac catheterization.

RESULTS

Among 499 respondents, 57% (95% CI 53%-62%) were willing to enroll the patient. Among 207 cardiologists unwilling to enroll, 55% (95% CI 48%-61%) would be willing if they knew the patient did not have very high-risk features on stress imaging, yielding a total of 80% (95% CI 76%-83%) of cardiologists willing to enroll. No differences were observed among different types of cardiologists (interventional, invasive/noninterventional, and noninvasive). Seventy-one percent (95% CI 67%-75%) were more likely to try initial medical therapy after the publication of the Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation trial results.

CONCLUSIONS

Most surveyed cardiologists were willing to enroll SIHD patients with at least moderate ischemia into a trial with an initial noninvasive strategy arm. These findings support the feasibility of planning a large-scale trial to test the role of cardiac catheterization and revascularization in the initial management of SIHD patients with moderate or severe ischemia.

Prognostic value of automated vs visual analysis for adenosine stress myocardial perfusion SPECT in patients without prior coronary artery disease: a case-control study

PURPOSE

We aimed to evaluate the prognostic value of automated quantitative hypoperfusion parameters derived from adenosine stress myocardial perfusion SPECT (MPS) for predicting sudden or cardiac death (CD) in case-controlled patients with suspected coronary artery disease (CAD).

METHODS

We considered patients with available adenosine stress Tc-99m sestamibi MPS scans and follow-up information. 81 CD patients from a registry of 428 patients documented by the National Death Index were directly matched in a retrospective case-control design to patients without CD by key clinical parameters (age by deciles, gender, no early revascularization, pre-test likelihood categories, diabetes, and chest pain symptoms). Multivariable analysis of stress MPS total perfusion deficit (STPD) and major clinical confounders were used as predictors of CD. Visual 17-segment summed stress segmental scores (VSSS) obtained by an expert reader, were compared to STPD.

RESULTS

CD patients had higher stress hypoperfusion measures compared to controls [STPD: 7.0% vs 3.6% (P < .05), VSSS: 5.3 vs 2.1 (P < .05)]. By univariate analysis, STPD and VSSS have similar predictive power (the areas under receiver operator characteristics curves: STPD = 0.64, VSSS = 0.63; Kaplan-Meier models: χ(2) = 7.59, P = .0059 for STPD and χ(2) = 11.10, P = .0009 for VSSS). The multiple Cox proportional hazards regression models with continuous perfusion measures showed that STPD had similar power to normalized VSSS as a predictor for CD (χ(2) = 4.92; P = .027) vs (χ(2) = 8.90; P = .003).

CONCLUSIONS

Quantitative analysis is comparable to expert visual scoring in predicting CD in a case-controlled study.

Importance of residual myocardial ischemia after intervention in the genesis of cardiovascular events among patients with chronic coronary artery disease

Recent randomized clinical trials support the strategy of ischemia-guided management for patients with stable ischemic heart disease. The application of serial testing to examine the efficacy of therapeutic intervention for ischemia suppression and to document the extent and severity of ischemia provides an important means to guide clinical decision making. This review provides a synopsis of available evidence on serial testing and meaningful thresholds for application of paired rest/stress myocardial perfusion single photon emission computed tomography imaging.

Comparative Effectiveness of Exercise Electrocardiography With or Without Myocardial Perfusion Single Photon Emission Computed Tomography in Women With Suspected Coronary Artery Disease

Background—

There is a paucity of randomized trials regarding diagnostic testing in women with suspected coronary artery disease (CAD). It remains unclear whether the addition of myocardial perfusion imaging (MPI) to the standard ECG exercise treadmill test (ETT) provides incremental information to improve clinical decision making in women with suspected CAD.

Methods and Results—

We randomized symptomatic women with suspected CAD, an interpretable ECG, and ≥5 metabolic equivalents on the Duke Activity Status Index to 1 of 2 diagnostic strategies: ETT or exercise MPI. The primary end point was 2-year incidence of major adverse cardiac events, defined as CAD death or hospitalization for an acute coronary syndrome or heart failure. A total of 824 women were randomized to ETT or exercise MPI. For women randomized to ETT, ECG results were normal in 64%, indeterminate in 16%, and abnormal in 20%. By comparison, the exercise MPI results were normal in 91%, mildly abnormal in 3%, and moderate to severely abnormal in 6%. At 2 years, there was no difference in major adverse cardiac events (98.0% for ETT and 97.7% for MPI; P =0.59). Compared with ETT, index testing costs were higher for exercise MPI ( P <0.001), whereas downstream procedural costs were slightly lower ( P =0.0008). Overall, the cumulative diagnostic cost savings was 48% for ETT compared with exercise MPI ( P <0.001).

Conclusions—

In low-risk, exercising women, a diagnostic strategy that uses ETT versus exercise MPI yields similar 2-year posttest outcomes while providing significant diagnostic cost savings. The ETT with selective follow-up testing should be considered as the initial diagnostic strategy in symptomatic women with suspected CAD.

Clinical Trial Registration—

http://www.clinicaltrials.gov . Unique identifier: NCT00282711.

Cost-effectiveness of coronary computed tomography and cardiac stress imaging in the emergency department: a decision analytic model comparing diagnostic strategies for chest pain in patients at low risk of acute coronary syndromes

Emergency department presentations with chest pain are expensive and often unrelated to coronary artery disease (CAD). Coronary computed tomographic angiography (CTA) may allow earlier discharge of low-risk patients, resulting in cost savings. We modeled clinical and economic outcomes of diagnostic strategies in patients with chest pain and at low risk of CAD: exercise electrocardiography (ECG), stress single-photon emission computed tomography (SPECT), stress echocardiography, and a CTA strategy comprising an initial CTA scan with confirmatory SPECT for indeterminate results. Our results suggest that a 2-step diagnostic strategy of CTA with SPECT for intermediate scans is likely to be less costly and more effective for the diagnosis of a patient group at low risk of CAD and a prevalence of 2% to 30%. The CTA strategies were cost saving (lower costs, higher quality-adjusted life-years) compared with stress ECG, echocardiography, and SPECT. Confirming intermediate/indeterminate CTA scans with SPECT results in cost savings and quality-adjusted life-year gains due to reduced hospitalization of patients who returned false-positive initial CTA test. However, CTA may be associated with a higher event rate in negative patients than SPECT, and the diagnostic and prognostic information for the use of CTA in the emergency department is evolving. Large comparative, randomized, controlled trials of the different diagnostic strategies are needed to compare the long-term costs and consequences of each strategy in a population of defined low-risk patients in the emergency department.

The significance of transient ischemic dilation in the setting of otherwise normal SPECT radionuclide myocardial perfusion images

BACKGROUND

Transient ischemic dilation (TID) in the setting of an abnormal SPECT radionuclide myocardial perfusion imaging (MPI) study is considered a marker of severe and extensive coronary artery disease (CAD). However, the clinical significance of TID and its association with CAD in patients with an otherwise normal MPI study is unclear.

METHODS

From a database of patients who underwent MPI over a 9-year period, 96 without known cardiac history who had normal image perfusion patterns, and who underwent coronary angiography within 6 months, were identified. TID quantitative values were derived. To adjust for varying stress and image protocols, a TID index based on published threshold values was derived for each patient, with >1 considered as TID. We examined the relationship of TID to the presence/extent of CAD, and to a CAD prognostic index. TID was also correlated with patient survival. To address referral bias, survival in a separate cohort of 3,691 patients with a normal perfusion MPI who did not undergo angiography in the 6-month interval was correlated with the presence and severity of TID.

RESULTS

For 28 (29.2%) patients with normal MPI perfusion patterns but with TID, there was no increased incidence of CAD, multivessel or left main disease, or a higher prognostic index compared with no TID. In addition, there was no increased mortality associated with TID in both the angiography cohort and in the patients who did not undergo immediate angiography.

CONCLUSIONS

TID in patients with an otherwise normal SPECT MPI study does not increase the likelihood of CAD, its extent or severity, and is not associated with worsened patient survival.

Impact of ischaemia and scar on the therapeutic benefit derived from myocardial revascularization vs. medical therapy among patients undergoing stress-rest myocardial perfusion scintigraphy

AIMS

Although pre-revascularization ischaemia testing is recommended, the interaction between the extent of ischaemia and myocardial scar with performance of revascularization on patient survival is unclear.

METHODS AND RESULTS

We identified 13 969 patients who underwent adenosine or exercise stress SPECT myocardial perfusion scintigraphy (MPS). The percent myocardium ischaemic (%I) and fixed (%F) were calculated using 5 point/20-segment MPS scoring. Patients lost to follow-up (2.8%) were excluded leaving 13 555 patients [35% with history (Hx) of known coronary artery disease (CAD), 65% exercise stress, 61% male, age 66 ± 12]. Follow-up was performed at 12-18 months for early revascularization and at >7 years for all-cause death (ACD) (mean follow-up 8.7 ± 3.3 years). All-cause death was modelled using Cox proportional hazards modelling adjusting for logistic-based propensity scores, MPS, revascularization, and baseline characteristics. During FU, 3893 ACD (29%, 3.3%/year) and 1226 early revascularizations (9.0%) occurred. After risk-adjustment, a three-way interaction was present between %I, early revascularization, and HxCAD, such that %I identified a survival benefit with early revascularization in patients without prior myocardial infarction (MI), whereas no such benefit was present in patients with prior MI (overall model χ(2)= 3932, P < 0.001; interaction P < 0.021). Further modelling revealed that after excluding patients with scar >10% total myocardium, %I identified a survival benefit in all patients.

CONCLUSION

In this large observational series with long-term follow-up, patients with significant ischaemia and without extensive scar were likely to realize a survival benefit from early revascularization. In contrast, the survival of patients with minimal ischaemia was superior with medical therapy without early revascularization.

Comparison of long-term mortality risk following normal exercise vs adenosine myocardial perfusion SPECT

BACKGROUND

A higher frequency of clinical events has been observed in patients undergoing pharmacological vs exercise myocardial perfusion single-photon emission computed tomography (SPECT). While this difference is attributed to greater age and co-morbidities, it is not known whether these tests also differ in prognostic ability among patients with similar clinical profiles.

METHODS AND RESULTS

We assessed all-cause mortality rates in 6,069 patients, followed for 10.2 ± 1.7 years after undergoing exercise or adenosine SPECT. We employed propensity analysis to match exercise and adenosine subgroups by age, gender, symptoms, and coronary risk factors. Within our propensity-matched cohorts, adenosine patients had an annualized mortality rate event rates that was more than twice that of exercise patients (3.9% vs 1.6%, P < .0001). Differences in mortality persisted among age groups, including those <55 years old. In the exercise cohort, mortality was inversely related to exercise duration, with comparable mortality noted for patients exercising <3 min and those undergoing adenosine testing.

CONCLUSIONS

Among patients with normal stress SPECT tests, those undergoing adenosine testing manifest a mortality rate that is substantially higher than that observed among adequately exercising patients, but comparable to that observed among very poorly exercising patients. This elevated risk underscores an important challenge for managing patients undergoing pharmacological stress testing.

SPECT/PET myocardial perfusion imaging versus coronary CT angiography in patients with known or suspected CAD

Stress SPECT myocardial perfusion imaging (MPI) is the most commonly utilized stress imaging technique for patients with suspected or known coronary artery disease (CAD) and has a robust evidence base including the support of numerous clinical guidelines. Gated SPECT is a well-established noninvasive imaging modalities that is a core element in evaluation of patients with both acute and stable chest pain syndromes. Over the past decade, PET has become increasingly used for the same applications. By comparison, cardiac computed tomography (CT) is a more recently developed method, providing non-invasive approaches for imaging coronary atherosclerosis and coronary artery stenosis. Non-contrast CT for imaging the extent of coronary artery calcification (CAC), in clinical use since the mid-1990's, has a very extensive evidence base supporting its use in CAD prevention. While contrast-enhanced CT for noninvasive CT coronary angiography (CCTA) is relatively new, it has already developed an extensive base of evidence regarding diagnosing obstructive CAD and more recently evidence has emerged regarding its prognostic value. It is likely that non-contrast CT or CCTA for assessment of extent of atherosclerosis will become an increasing part of mainstream cardiovascular imaging practices as a first line test. In some patients, further ischemia testing with MPI will be required. Similarly, MPI will continue to be widely used as a first-line test, and in some patients, further anatomic definition of atherosclerosis with CT will also be appropriate. This review will provide a synopsis of the available literature on imaging that integrates both CT and MPI in strategies for the assessment of asymptomatic patients for their atherosclerotic coronary disease burden and risk as well as symptomatic patients for diagnosis and guiding management. We propose possible strategies through which imaging might be used to identify asymptomatic candidates for more intensive prevention and risk factor modification strategies as well as symptomatic patients who would benefit from referral to invasive coronary angiography for consideration of revascularization.