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CT in cardiac emergencies

Dr MahendraCardiology,JIPMER

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Introduction• More than 9 million ED pts with acute chest pain are seen annually in the United

States alone.• health-care costs of $13 to $15 billion. • incidence of ACS in pts without a history of CV events with negative ECG and

cardiac biomarkers is low (between 1% and 8%). • consequences of missing occult ACS are a source of both morbidity and mortality

in such pts and significant malpractice litigation.

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Current Standard Diagnostic Testing• 1.exercise treadmill testing-• Symptom-limited exercise treadmill testing is recommended in pts who are capable of exercise.• not suitable in pts having left bundle-branch block, left ventricular hypertrophy, and paced

rhythms in baseline ECG. • study of 100 pts with acute chest pain one hour after admission• 23% had positive tests• 38% had negative tests • 39% had nondiagnostic tests • uncomplicated non–Q-wave AMI diagnosed in 2%, indicating limited feasibility of this test for early

triage

• Emergency room technetium-99m sestamibi imaging to rule out acute myocardial ischemicevents in patients with nondiagnostic electrocardiograms. J Am Coll Cardiol. 1993;22:1804 –1808.

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• Single-photon emission computed tomography (SPECT)-• complex, costly, and time-consuming (ie, 150 minutes for stress SPECT). • mostly not available 24/7.• High radiation exposure.• detects significant stenosis with excellent sensitivity 90% and good specificity

(67% to 78%) when compared with coronary angiography.

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• Rest echocardiography-• relatively inexpensive.• easy to perform, and widely available. • lower sensitivity of rest echocardiography when compared with rest SPECT for the

detection of myocardial ischemia.• Stress echocardiography-• adds significant value to functional assessment at rest.• increases both negative predictive value (NPV) (98.8%) and positive predictive value (PPV)

(78%).• requires highly experienced sonographers and interpreting physicians and is often not

available 24/7.

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CT in emergency department• negative predictive value of coronary CT angiography for ACS will depend on the

prevalence of coronary disease in the study population.• 99% negative predictive value of coronary CT angiography for coronary disease

at both the patient and the vessel levels in a population with a disease prevalence of less than 25%. • coronary CT angiography as an effective noninvasive examination to rule out

obstructive coronary artery stenosis. • CT angiography is at least as accurate as nuclear imaging and allows the safe and

rapid discharge of low- to intermediate- risk ACS pts.

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Evidence for coronary CTA in suspected ACS

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• first randomized trial was the single-center 64-STAT trial.

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• CT-STAT trial-• randomized 699 pts at 16 study cites with TIMI scores 4 to either coronary CTA

(n= 361) or rest-stress MPI (n = 338).• Outcomes were similar to 64-STAT • reduced diagnostic time for coronary CTA (2.9 hours vs 6.3 hours; P < .001) • lower ED cost of care ($2137 vs $3458; P < .001) • no missed ACS

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• ROMICAT-II trial- • 1000 pts to either early coronary CTA or to SOC. • TIMI scores did not limit entry criteria. • SOC included any available management strategy deemed appropriate by the

treating physicians. • Coronary CTA as compared with SOC resulted in a reduced median length of stay

(8.6 hours vs 26.7 hours; P <.001)• time to diagnosis (5.8 hours vs 21.0 hours; P < .001)• increase in direct discharges (47% vs 12%; P < .001).

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ACRIN-PA trial

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SOP IN ED for chest pain

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Appropriate diagnostic strategy ??1. A 50-year-old man presents with several hours of episodic chest pain at rest

accompanied by nausea. The baseline EKG shows no abnormality, but with chest pain, there is 1 mm of down-sloping ST depression that normalizes with nitroglycerin. The baseline troponin level is greater than institutional limits of normal and increases slightly after 4 hour.

2. A 45-year-old man presents with 3 non exertional chest pain episodes in the past day. The EKG shows nonspecific ST-T changes without serial changes, and troponin levels are within normal limits. His father had an acute MI at the age of 54. He has been taking 1 aspirin a day.

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• TRO CT precludes the need for additional diagnostic testing in over 75% of patients with low to intermediate risk of ACS and provides the additional advantage of helping find noncoronary diagnoses that explain the presenting complaint in 11% of ED pts. • TRO studies for coronary disease, aortic dissection, pulmonary embolism, and

other acute chest conditions.

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subtotal occlusion of the proximal RCA. pt underwent stress nuclear perfusion imaging, which demonstrated a reversible inferolateral and inferoseptal perfusion defect.

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 Saphenous vein graft to the anterior descending artery with significant stenosis of its distal anastomosis (arrows).

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Saphenous vein graft to the right coronary artery with significant stenosis of its distal anastomosis.

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Other cause of chest pain in ED• 1.Aortic dissection- • CT is the most widely used modality,• sensitivity and specificity of nearly 100% . • primary finding on a contrast-enhanced CT is the identification of the

intimomedial flap that separates the true and false lumens. • Additional findings – • displacement of intimal calcifications caused by the false lumen dissecting

through the media • compression of the true lumen by the larger false lumen.

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2. Pulmonary embolism• CT pulmonary angiography has become the primary method by which PE is

evaluated in most institutions. • wide range of sensitivities (53–100%) and specificities (81–100%)• primary imaging feature of PE is identification of an intraluminal full or partial

pulmonary arterial filling defect. • Other findings include pleural-based, wedge-shaped consolidation oligemia and

pleural effusion.

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Conclusions

• (1) fast, relatively simple, available 24/7 in both tertiary and community hospital settings.• (2) it uniquely provides a direct and noninvasive visualization for CAD.• (3) rapid early discharge of nearly half of all pts with cardiac pain may be possible

by excluding CAD. • (4) detection of nonobstructive CAD provide more accurate short- and long-term

prediction of cardiovascular event risk and in improved preventive strategies.• 5. Information on noncoronary cardiac pathologies such resting global and

regional LV function as well as extracardiac pathologies. • Recent AHA/ACC guidelines recommend coronary CT as an alternative to

conventional stress testing (class IIa recommendation, level of evidence B).

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