Disclosures None. Background. ED Testing. Imaging Options in Guiding Therapy for Evaluating CAD in the Emergency Room 10/1/15.

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1 Imaging Options in Guiding Therapy for Evaluating CAD in the Emergency Room Venkat R. Pasnoori, MD, MPH, FACC Providence Medical Group - Cardiology Disclosures None Background Ischemic Cascade 6-8 million annual presentations to ED with chest pain >50% patients with acute chest pain get admitted to hospital for comprehensive cardiac evaluation Less than one third are eventually diagnosed with CAD 2-4% patients with true ACS are inadvertently discharged home from ED Missing ACS is single biggest category for malpractice claims payouts in ED (25-40% of ED malpractice claims) Chest pain accounts for billion dollars in healthcare costs annually Regional flow heterogeneity and systolic dysfunction precede chest pain in the ischemic cascade Rest image during symptoms can detect or exclude flow heterogeneity or regional wall motion abnormalities Non-invasive imaging studies: regional flow heterogeneity has higher sensitivity for ACS while regional systolic dysfunction has a higher specificity If symptoms have abated, provocative stress testing may be necessary to exclude CAD Alternate approach to functional imaging is direct visualization of the coronary artery tree to detect obstructive CAD by CT angiography ED Testing High diagnostic sensitivity and high NPV for ACS are key attributes for testing strategies given the importance of capturing all ACS patients Since sensitivity and specificity vary inversely, this high sensitivity usually comes at the expense of some compromise in diagnostic specificity and PPV Low specificity can result in unnecessary downstream testing particularly ICA especially when applied to population with low prevalence of disease 1

2 Rest Imaging * Radionuclide myocardial perfusion imaging (rmpi) (Class I, AUC-A) * Echocardiography (Class I, AUC-A) * Coronary computed tomographic angiography (CCTA) (Class IIa, AUC-U for acute CP, A for nonacute symptoms likely ischemic unable to exercise) * Cardiovascular magnetic resonance (CMR) Rest imaging less helpful in diagnosing ACS in patients with prior MI Low risk patient with negative rest imaging can be managed as outpatient Stress Testing Recommended to provoke ischemia in low-intermediate risk patients with suspected ACS after at least 6-8 hours of observation without recurrent ischemic discomfort, unchanged EKG and two troponin levels at least 6 hours apart are normal Early outpatient stress test to be performed within 72 hours of ED discharge is reasonable alternative for reliable and compliant patient * Stress myocardial perfusion imaging (Class I, AUC-A): exercise vs pharmacologic stress, fast track protocols, stress only imaging * Stress echocardiography (Class I, AUC-A) * Stress PET * Stress CMR Current Recommendations Intermediate to high probability: hospital admission, early ICA/ revascularization Low to intermediate probability: - ongoing CP: resting rmpi or 2D echo (+/- contrast) - within 2 hours of symptoms: resting rmpi Possible ACS with prior MI: provocative stress testing Low to intermediate probability without CP after 6-8 hours of observation and negative troponins: provocative stress testing Low to intermediate probability, normal renal function, can lay still and hold breath, CCTA reasonable Functional testing Vs CCTA FT may be nonideal since patients often have been treated with antianginal agents and submaximal stress tests are not uncommon Fewer individuals with nonobstructive CAD who are at risk of incident MI and mortality are recognized with a selective referral strategy on the basis of functional testing than with coronary imaging Findings evoke concerns that current practice paradigm of stress testing followed by ICA is ineffective at identifying individuals who should start treatment for CAD CCTA is promising noninvasive method for identification and exclusion of CAD an may provide a diagnostic paradigm to curb unnecessary invasive testing Normal exercise or adenosine SPECT-MPI: cardiac event rate 0.6%/yr, warranty period months CONFIRM trial: Normal CCTA cardiac event rates 0.01% to 0.24%/yr, warranty period >5 yrs Diagnosis of Obstructive CAD CCTA for Acute Chest Pain in ED: RCT s 2

3 10/1/15 Anatomy-Based Revascularization Ischemia-Guided Revascularization: Observational Data 15,223 patients w/o known CAD followed for 2.1 years (IQR yrs). Propensity to adjust post-test referral to medical therapy or revascularization to simulate RCT High risk anatomic CAD inclusive of LM, 3VD and 2VD plus plad Anatomic-Physiologic Discordance Fractional Flow Reserve 20% patients with apparently significant stenoses are identified as having normal FFR s 13% patients thought to have nonsignificant stenoses have abnormal FFR s FFR guidance has been associated with 28% lower event rate compared with anatomic stenosis guided PCI alone Absence of this functional information is a potential limitation for CCTA Assessment of Lesion Ischemia by FFR is the only method to result in improved Event-Free Survival Recent meta-analysis: Patient level: sensitivity 89%, specificity 71%, AUC 0.89 (greater than CTA). Vessel level sensitivity 70%, specificity 90% 3

4 NXT Trial: FFRct Accuracy (Per-Patient) Per-Patient Diagnostic Performance Platform Trial Aim: To determine whether use of a CTA/FFRct guided strategy as compared to standard practice will reduce the rate of invasive angiograms that show no obstructive CAD, without increasing the occurrence of major cardiac events Enrolled a symptomatic intermediate risk population for whom testing is currently recommended Use of CT/FFRct in patients with planned ICA was associated with a reduction in the rate of finding no obstructive CAD at ICA from 73% to 12% - similar results in all subgroups - no differences in MACE or radiation exposure - no differences in revascularization rates Use of FFRct resulted in cancellation of 61% of ICA s and doubled the availability of functional data at PCI/CABG Primary Endpoint: Invasive Cath w/o Obstructive CAD Safety Endpoints and Data at Revascularization Diagnostic performance of Non-Invasive Imaging Vs FFR 4

5 Case Examples: Obstructive CAD Combined Multimodality Algorithm based around the use of CCTA for CP evaluation Thank You Fractional Flow Reserve FFRct FFRct: Computational fluid dynamics applied to standard CCTA acquisitions without need for additional imaging, modification of protocols, additional radiation doses or medication administration Recent meta-analysis: Patient level: sensitivity 89%, specificity 71%, AUC 0.89 (greater than CTA). Vessel level sensitivity 70%, specificity 90% FFRct may reduce the number of false-positive studies that identify anatomical CAD of no hemodynamic significance and identify lesions that may benefit from revascularization CCTA combined with FFR may optimize the prediction of the therapeutic benefit of intervention and has potential to serve as an effective gatekeeper to curb unnecessary ICA 5