Usefulness of 64-slice MDCT as an

initial diagnostic approach in

patients with acute chest pain

Sung-A Chang, Sang Il Choi, Eue-Keun Choi, et al. Sung-A Chang, Sang Il Choi, Eue-Keun Choi, et al.

Am Heart J 2008;156:375-83Am Heart J 2008;156:375-83

Journal Club 7th August 2008

Dr. Rashidi Ahmad

Dr. Emily Tan

Dato’ Dr. Azhari Rosman

IntroductionIntroduction

• Appropriate triage of patients with acute CP is

the most important issues for EPs

– high morbidity and mortality of missed

cases of ACS

• To date, the triage of patients with CP

depends on the individual's symptom history,

serial ECG, and cardiac biomarkers.

Pope JH, et al. Missed diagnoses of acute cardiac ischemia in the emergency department. N Engl J Med 2000;342:1163-70.

Rationale of the studyRationale of the study

• Patients with ACS may have non-diagnostic findings

on their initial evaluation.

• Current diagnostic tools have limited capability to

define the etiology of acute chest pain.

• As a result: overcrowded state of ED, unnecessary

admission & misappropriation of resources.

• Solution…

Antman EM, et al. The TIMI risk score for USA/NSTEMI: a method for prognostication and therapeutic decision making. JAMA 2000;284:835-42.

MDCTMDCT

• With rapid technical improvements, cardiac MDCT permits noninvasive imaging of coronary anatomy with high accuracy & may also provide insight into non-coronary causes of chest pain.

Raff GL, et al. Diagnostic accuracy of noninvasive coronary angiography using 64-slice spiral computed tomography. J Am Coll Cardiol 2005;46:552-7.

Johnson TR, et al. ECG-gated 64- MDCT angiography in the differential diagnosis of acute chest pain. Am J Roentgenol 2007;188:76-82.

MDCTMDCT

• 64-slice MDCT in acute chest pain is safe, feasible

and facilitates early triage of acute CP in low-risk

patients, primarily relying on their negative MDCT

result

• The appropriate use and timing of MDCT in the

ED are still unclear and its role in patients with

different risk profiles has not been studied yet.

White CS, et al. Chest pain evaluation in the ED: can MDCT provide a comprehensive evaluation? Am J Roentgenol 2005;185:533-40.

Rubinshtein R, et al. Usefulness of 64-slice MDCT for diagnosing ACS & predicting clinical outcome in ED patients with chest pain of uncertain origin. Circulation 2007;115:1762-8.

Objectives Objectives

• To investigate whether 64-slice MDCT as

part of the initial diagnostic strategy

- ED and hospital length of stay (LOS)

- admissions

- 30-day MACE

in patients presenting with chest pain

stratified based on the pretest probability for

ACS.

Measured outcomeMeasured outcome

• ED length of stay

• Hospital length of stay (LOS),

• Admissions

• 30-day major adverse cardiac events (MACE)

MethodsMethods

• Approved by IRB of Seoul National University Bundang Hospital, and written informed consent was obtained from all patients

• Prospective, randomization study from May 2006 to February 2007

• No sample size calculation

• Patients presenting to the ED were cared for by attending physicians trained in EM/internal Med

• Inclusion criteria: Patients older than 18 years presenting to the ED with acute chest pain syndrome

• Exclusion criteria: • Patients deemed very low and very high risk.

• Constant arrhythmia

• Hemodynamic or clinical instability

• History of allergy to radio-contrast dye

• Documented renal insufficiency,

• Pregnancy or women of childbearing age who are not using contraception

• CI to β blockade,

• Recent (b1 month) diagnostic work-up for coronary disease

MDCT protocolMDCT protocol

• MDCT: Brilliance 64; Philips Medical Systems,

Best, The Netherlands

• Contrast: a bolus of 80 mL iomeprol (Iomeron 400;

Bracco, Milan, Italy)

• All MDCT data sets were analyzed with the clinical

information by a single, experienced radiologist

immediately after acquisition.

A month after the index ED visit, clinical status and cardiacevents were assessed by individual interviews and using thehospital computer database.

2 cardiologist

Statistical analysis

• All values are expressed as means ± SD or percentages

• Student t test: to compare the continuous variables with normal distribution.

• ED and hospital LOS (negatively skewed) - medians (interquartile ranges)

• Pairwise group comparisons: Mann-Whitney U test.

• Pearson's χ2 test or Fisher exact test - categorical variables.

• One-way analysis of variance with Sheffe's post hoc test for parametric variables or linear-by-linear association for categorical variables was used to determine differences between 3 groups.

• Probability values of <.05 were considered statistically significant.

(high, intermediate, low

probability)

21% 42% 37%

Low probability patients: younger and had less history of hypertension, diabetes, dyslipidemia & CAD than high-probability patients

MDCT image acquisition

• The mean time from ED arrival to MDCT imaging:

1.67 ± 1.62 hours.

• Time for patient preparation & scanning:15.2 ± 4.5

min & for image reconstruction and interpretation:

24.2 ± 3.7 min

• Coronary artery image quality: good in 92%, adequate

in 6%, and poor in 2% on a segmental basis.

• Reasons for poor image quality: motion artifact (56%),

blooming artifact (28%), or low contrast-to-noise ratio

(16%).

P:0.07

144 (54%) patients were discharged from the ED and 122 (46%) patients were hospitalized

Study outcomeStudy outcome

• In the conventional strategy, 57 (85.1%) of 67

admitted patients underwent invasive coronary

angiography and 39 (58%) were ultimately

diagnosed with an ACS.

• In the MDCT-based strategy, 39 (71%) of 55

admitted patients were ultimately diagnosed

with an ACS.

• Reductions in unnecessary admissions were

more prominent in patients with intermediate

probability (20% for control vs 4% for the

MDCT-based strategy, P = .015).

• There were no differences in unnecessary

admissions in low probability groups possibly

because of the small number of patients

admitted in both strategies

Emergency department LOS

• Emergency department LOS was not different

between the conventional and MDCT strategies (4.8

[3.1-7.6] vs 4.6 [3.2-7.1] hours, P = .98).

• In patients with intermediate probability for ACS, there

was a non-significant trend toward decreased ED

LOS in the MDCT-based strategy (6.0 [4.1-8.9] vs 4.5

[3.2-7.7] hours, P = .055)

• There were no differences in ED LOS between

strategies in low- and high-risk patients.

Hospital LOSHospital LOS

• Hospital LOS was decreased in the MDCT-

based strategy compared with the conventional

strategy for all patients studied (7.1 [4.1-97.5] vs

26.6 [4.8-131.1] hours, P = .049).

• Subgroup analysis, hospital LOS was

significantly decreased only in patients with

a high probability for ACS (94.7 [56.9-159.9]

vs 155.2 [95.5-266.1] hours, P = .036)

A, Length of ED stay showed no difference between the conventional and MDCT-based strategies, which was similar in subgroup analysis according to the risk for ACS.

B, Length of hospital stay tended to be lower in the MDCT-based strategy. In subgroup analysis, hospital LOS was significantly reduced in high-risk patients (*P < .05).

F/upF/up

• One-month follow-up was completed in all patients

• One patient in the conventional strategy – non-

fatal MI

• None of the patients discharged from the ED in the

MDCT-based strategy experienced MACE at follow-

up.

• No patients experienced clinical or laboratory

evidence of contrast-induced nephropathy during

follow-up.

Study limitations/opportunity

• Small numbers of patients, especially low-

risk individuals who had significant MDCT

findings.

• The follow-up period was too short to

assess future cardiac events in patients

presenting with acute chest pain

Conclusions

• Application of MDCT as part of the initial

diagnostic approach for patients presenting

with acute CP to the ED is safe, efficient, and

reduces avoidable admissions in patients

with an intermediate risk for ACS.

• The use of MDCT to assist in triage of CP in

the ED needs to be applied in the context of

the patient risk profile and available

conventional diagnostic tests.