characterization of complex coronary artery stenosis morphology by coronary computed tomographic...

Characterization of Complex Coronary Artery Stenosis Morphology by Coronary

Computed Tomographic Angiography

Brett M. Wertman, Victor Y. Cheng, Saibal Kar, Heidi Gransar, Ryan A. Berg, Hursh Naik,

Rajendra Makkar, John D. Friedman, Jay N. Schapira, Daniel S. Berman

Cedars-Sinai Medical Center, Los Angeles, CA

CT detection of complex stenosis morphology

Disclosures

• Funding from the Lincy Foundation (Beverly Hills, California)

• Conflicts of interest: None


Background 1

• Contemporary clinical trials1-4 have adopted ≥ 70% diameter stenosis on invasive coronary angiography (ICA) as threshold to qualify for randomization to revascularization

1 RITA-2 trial participants. RITA-2. Lancet 1997;350:461-8.

2 Hueb W, et al. MASS-II. J Am Coll Cardiol 2004;43:1743-51.

3 McFalls EO, et al. N Engl J Med 2004;351:2795-804.

4 Boden, WE, et al. COURAGE. N Engl J Med 2007;356:1503-16.


Background 2

• Stenosis morphology is an important determinant in PCI complication rate1,2

1 Ellis SG, et al. Circulation 1990;82:1193–1202.

2 Ellis SG, et al. Circulation 1991;84:644–653.

• Published experience of CCTA performance in complex coronary lesions undergoing PCI have primarily focused on total occlusions3-5

3 Yokoyama N, et al. Catheter Cardiovasc Interv 2006;68:1-7.

4 Soon KH, et al. J Interv Cardiol 2007;20:359-66.

5 Mollet NR, et al. Am J Cardiol 2005 Jan 15;95(2):240-3.


Aims

1 Determine capability of CCTA in characterizing complex stenosis morphologies

2 Determine utility of complex stenosis morphology on CCTA in predicting PCI procedure duration and contrast use


Methods

• 85 consecutive patients who underwent ICA within 30 days after CCTA

• CCTA on a Siemens DSCT scanner1 PO/IV metoprolol for HR > 70

2 Sublingual NTG

3 Gated, noncontrast CCS

4 Gated, contrast enhanced (92 ml), helical acquired angiography


Methods: CCTA

Reconstruction– 0.6 mm thickness, 0.3 mm increment

– End-systole: 40% of R-R

– Diastole: 65%, 70%, 75%, 80% or R-R

– Manual ECG editing for arrhythmic artifact

– Sharp kernel if stent present or CCS > 100


Methods: CCTA

CCTA Interpretation– Consensus by 2 blinded readers

– Vital Images workstation

– Native segments ≥ 2.0 mm in diameter

– Stented and bypassed segments excluded

– Oblique multiplanar reformation and oblique maximal intensity projection preferred


Methods: CCTA

CCTA InterpretationSevere stenosis defined by ≥ 70% diameter stenosis on

long-axis visual evaluation (see example figures)

Quantification of stenosis severity performed independently

Proximal LCX Mid RCA


Methods: CCTA

CCTA InterpretationComplex stenosis defined by any ACC/AHA

Type-C morphology criteria (Ellis SG, et al.)

1) Ostial involvement

2) Major branch involvement

3) Marked vessel tortuosity proximal to lesion

4) > 90º angle at lesion site

5) > 20 mm lesion length

6) Total occlusion


Methods: ICA

Acquisition– Standard technique

– GE digital X-ray, AGFA Heartlab workstation

Data collection– Occurrence of PCI

– PCI duration (minutes)

– Total contrast use (ml)


Methods: ICA

ICA Interpretation

– Consensus by 2 blinded readers

– Severe stenosis defined by ≥ 70% diameter stenosis on visual inspection

– Type-C morphology assessment similar to CCTA

– Quantification of stenosis severity performed independently


Methods: Statistics

• Continuous variables– Means ± Standard Dev

– Ranges

• Comparing PCI time and contrast use:– Analysis of covariance (ANCOVA) with

adjustments for age and BMI

– Analysis of log-transforms performed to satisfy ANCOVA assumptions


Results

Population– 74% men

– 84% referred either to follow-up on prior SPECT (44%) or for symptoms (40%)

– Mean age: 67 ± 11 years

– Mean BMI: 27.7 ± 4.6 kg/m2

– Mean Agatston calcium score: 734 ± 873

– Mean heart rate at CCTA: 59 (39 to 112)


Results

• 940 segments in 328 arteries were evaluated

• 93 segments had ≥ 70% stenosis on ICA by visual inspection– Median stenosis severity 73.3%

• 101 segments had ≥ 70% stenosis on CCTA by visual inspection– Median stenosis severity 77.3%


Results

CCTA performance in ≥ 70% stenoses

• Detected 84 of 93 lesions (90%)

• Detected 49 of 52 patients (94%)

• False positive in 17 segments and 8 patients


Results

Detection of ≥ 70% stenosis by visual CCTA and ICA evaluation

≥ 70%

stenotic on ICA

Correctly identified on CCTA (%)

Not identified on CCTA (%)

False positive on CCTA (%)

Total 93 84 (90) 9 (10) 17 (17)

Left main* 8 8 (100) 0 (0) 1 (11)

LAD territory 37 33 (89) 4 (11) 10 (23)

LCX territory 23 19 (83) 4 (17) 1 (5)

RCA territory 25 24 (96) 1 (4) 5 (17)

* For left main, threshold was ≥ 50% stenosis


Results

CCTA performance in ≥ 70% stenotic Type-C stenoses

• Detected 42 of 53 lesions (79%)

• Detected 31 of 35 patients (89%)

• False positive in 7 segments and 3 patients


Results

CCTA detection of specific Type-C morphologies

• Correctly identified 46 of 62 lesions (74%)

• Most frequent false positive: branch involvement (12 cases)

• Most frequent miss: lesion length > 20 mm (7 cases)


Results

Correct and incorrect characterization of Type-C lesions by CCTA

n (on ICA)

Correctly identified on CCTA (%)

Not identified on CCTA (%)

False positive on CCTA (%)

Total 62 46 (74) 16 (26) 22 (32)

Ostial 20 15 (75) 5 (25) 2 (12)

Crosses major branch 15 13 (93) 2 (7) 12 (48)

Total occlusion 9 7 (78) 2 (22) 3 (30)

> 20 mm in length 18 11 (61) 7 (39) 4 (26)

Proximal vessel tortuosity 0 0 (0) 0 (0) 1 (100)

> 90° angle at lesion 0 0 (0) 0 (0) 0 (0)

Ostial LAD involvement

Proximal RCA total occlusion

Left main plaque crossing LCX and involving ostial LAD

LCX

LAD

Examples of Type-C Morphologies on CCTA

Ostial LAD involvement

Proximal RCA total occlusion

Left main plaque crossing LCX and involving ostial LAD

LCX

LADLAD


Results

PCI, Procedure Time, and Contrast Use

• PCI performed in 36 patients for 46 lesion (none for total occlusion)

• Procedure time available in 34 patients• Contrast use available in 31 patients• Type-C morphology on CCTA was associated

with significantly increased procedure duration and contrast use


Results

Mean PCI time and contrast use in patients with and without a Type-C lesion on ICA and CCTA

ICA with no Type-C ICA with Type-C p-value*

Mean PCI time (min) 21.6 ± 12.8 43.7 ± 25.20.005 (0.003)†

Mean contrast use (ml) 137.1 ± 39.2 275.1 ± 152.30.003 (0.01)†

CCTA with no Type-C CCTA with Type-C P-value*

Mean PCI time (min) 21.5 ± 13.3 42.4 ± 24.70.009 (0.003)†

Mean contrast use (ml) 139.7 ± 47.4 262.6 ± 150.00.001 (0.02)†

* Adjusted for age and body-mass index† p-values obtained after log-tranforming PCI time and contrast use.


Main Discussion Points

• Step-wise assessment of ≥ 70% stenosis followed by presence of Type-C morphology on CCTA emulates real-life evaluation during ICA

• Our data showed CCTA detects ≥ 70% stenosis with additional value of identifying Type-C features



• Why did CCTA miss long lesions?– Underestimation of true lesion length by

standard oblique displays of CCTA

• Why did CCTA overcall branch involvement?– Limitations of spatial resolution– ICA underestimated lesion complexity?



• Type-C morphology on CCTA was significantly associated with longer PCI procedural time and contrast use

– Alerts clinician to higher risk of contrast-induced nephropathy from PCI

– Interventionalist may better plan PCI with advanced knowledge of lesion complexity


Limitations

• Modest sample size

• Referral bias

– Severe stenosis on CCTA more ICA referral

– Severe noncalcified lesions more ICA referral

– Contributed to high prevalence of disease

• Proximal tortuosity and highly angular lesions not represented

• Consensual reading not community practice

• Visual assessment has propensity for overestimation


Conclusions

• Using a visual cut-off of ≥ 70% diameter stenosis in vessels segments ≥ 2 mm in diameter, CCTA can predict lesions likely to reach ≥ 70% stenosis on ICA and discern associated complex morphologies

• Presence of complex, severely obstructive lesions on CCTA predicts greater contrast use and longer procedure duration during PCI


Recommendation

• CCTA readers should routinely describe the morphology of each detected severe stenosis

characterization of complex coronary artery stenosis morphology by coronary computed tomographic...

Documents

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diameter stenosis

complex coronary lesions

ccta reconstruction

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total occlusion slide

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