Rationale and Objectives
Cardiovascular (CV) disease is predominately influenced by CV risk factors and coronary computed tomography angiography (CTA) is capable of detecting early-stage coronary artery disease. We sought to determine the influence of CV risk factors on the prevalence of nonobstructive atherosclerosis in patients with normal-appearing coronary arteries in invasive coronary angiography (ICA).
Materials and Methods
In this retrospective analysis, we included 60 consecutive symptomatic patients, having undergone ICA and coronary CTA. Coronary dual source CTA was performed using electrocardiogram-triggered retrospective gated image acquisition at 40%–70% of RR interval (tube voltage 100–120 kV, tube current time product 320–440 mAs, 60 mL contrast, and flow rate 6 mL/s).
Results
Out of 60 patients (32 men, mean age 61 ± 11 years) with a normal coronary artery appearance in ICA, 45 (75%) patients showed atherosclerotic plaque in CTA. Plaque was present in 14 of 60 (23%) left main, 41 of 60 (68%) left anterior descending, 21 of 60 (35%) circumflex coronary arteries, and 24 of 60 (40%) right coronary arteries. More than 15% of all coronary artery segments showed detectable plaques. Interobserver agreement ranged from good to very good on a per-patient, per-vessel, and per-segment level. Patients with presence of plaque were significantly older ( P = 0.005) and showed higher incidence of arterial hypertension ( P = 0.019) as compared to individuals without coronary plaque in dual source computed tomography.
Conclusions
The prevalence of coronary atherosclerosis by CTA is substantial in symptomatic patients with normal invasive coronary angiogram. Hypertension and older age significantly influence the prevalence of atherosclerotic plaque and highlight the importance of risk-modifying therapy.
Introduction
Cardiovascular (CV) risk factors are widely used for risk assessment and direction of medical management in patients with suspected coronary heart disease. In patients with known coronary artery disease (CAD), strict risk factor control is crucial .
Coronary computed tomography angiography (CTA) can detect coronary artery stenosis noninvasively with excellent diagnostic accuracy and hence is successfully used to predict prognosis . Importantly, not only obstructive CAD increases the risk of all-cause mortality. There are substantial data consistently demonstrating a significant increase in risk for major adverse cardiac events (MACE) with increasing burden of atherosclerotic disease in CTA . Clinical relevance to detect even small amounts of coronary artery calcification (CAC), for instance, has been demonstrated by the Multi-Ethnic Study of Atherosclerosis (MESA), as individuals with CAC have significantly (threefold) increased risk for future cardiac events . It is also known that CAC has not only strong incremental value to predict cardiac events but also provides independent information in addition to traditional risk factors . The identification of nonobstructive, noncalcified lesions by CTA has also been shown to be of prognostic value . In 10,418 patients undergoing CTA, the international multicenter registry, CONFIRM, found a 6% higher risk of mortality for each additional segment with nonobstructive atherosclerotic plaque ( P = 0.021). Moreover, in patients with nonobstructive CAD, baseline statin use was associated with a 56% decreased mortality risk (hazard ratio 0.44) compared to patients without statin therapy. Statin use at baseline did not decrease the risk in patients without plaque in CTA .
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Materials and Methods
Study Design and Patient Population
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DSCT Data Acquisition and Image Analysis
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Analysis of Coronary Atherosclerosis
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Statistical Analyses
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Results
Patient and DSCT Scan Characteristics
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TABLE 1
Patient and Scan Characteristics
Mean ± SD or n (%) Patients characteristics Age (years) 61 ± 11 Male gender 32(53) Weight(kg) 80 ± 14 Height(m) 1.7 ± 0.1 BMI(kg/m 2 ) 28.0 ± 4.4 Obesity 15(25) Cardiovascular risk factors Hypertension 39(65) Diabetes mellitus 3(5) Smoker, current or prior 28(47) Familial history 17(28) Hyperlipidemia 39(65) Number of risk factors 2.1 ± 1.0 Scan parameters Tube voltage(100 kV) 39(65) Tube voltage(120 kV) 21(35) Tube current time product(mAs) 371 ± 60 CTDI(mGy) 37.4 ± 46.0 DLP(mGy∙cm) 450 ± 282 Effective dose(mSv) 6.3 ± 3.9
BMI, body mass index; CTDI, computed tomography dose index; DLP, dose length product; SD, standard deviation.
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Interobserver Differences for Plaque Detection
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TABLE 2
Segment-Based Analysis
Group Number of Diseased Segments Per Patient Number of Patients Number of Segments With Plaque Interobserver Differences 1 0 15 0 2 1–5 35 94 2 3 >5 10 69 10Total6016312
Number of computed tomography angiographically detected segments with any plaque.
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TABLE 3
Vessel-Based Analysis
O2 O1 No Plaque NCP CP MixedCoronary arteriesLM (PdV: 23.3%; PcV: 15.0%; κ: 0.83 [CI 0.67–0.99]) No plaque 46 0 0 0 NCP 0 5 0 0 CP 0 0 2 3 Mixed 0 0 1 3LAD (PdV: 68.3%; PcV: 41.7%; κ: 0.93 [CI 0.84–1.00]) No plaque 19 0 0 0 NCP 0 16 0 0 CP 0 0 0 3 Mixed 0 0 0 22LCX (PdV: 35.0%; PcV: 18.3%; κ: 0.97 [CI 0.91–1.00]) No plaque 38 1 0 0 NCP 0 10 0 0 CP 0 0 2 0 Mixed 0 0 0 9RCA (PdV: 40.0%; PcV: 20.0%; κ: 0.91 [CI 0.82–1.00]) No plaque 35 1 0 0 NCP 0 12 0 0 CP 0 0 1 2 Mixed 0 0 0 9Total All (PdV: 41.7%; PcV: 23.8%; κ: 0.92 [CI 0.87–0.97]) No Plaque NCP CP MixedSum No plaque 138 2 0 0 140 NCP 0 43 0 0 43 CP 0 0 5 8 13 Mixed 0 0 1 43 44Sum 138 45 6 51 240
No Plaque, disease-free condition; NCP, exclusively noncalcified plaque; CP, exclusively calcified plaque; Mixed, mixed plaque; LM, left main coronary artery; LAD, left anterior descending coronary artery; LCX, left circumflex coronary artery; RCA, right coronary artery; O1, Observer 1 (columns); O2, Observer 2 (rows); PcV, percentage of exclusively or partly calcified vessels; PdV, percentage of diseased vessels.
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Segment-Based Analysis
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Vessel-Based Analysis
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Patient-Based Analysis
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TABLE 4
Patient-Based Analysis with Regard to (a) Plaque Composition and (b) Number of Affected Vessels
(a) Plaque Composition O2 O1 No Plaque NCP CP Mixed No plaque 15 0 0 0 NCP 0 16 0 0 CP 0 0 0 0 Mixed 0 0 0 29
(b) Number of Affected Vessels Per Patient O2 O1 0 1 2 3 0 15 0 0 0 1 0 16 2 0 2 0 0 9 0 3 0 0 0 18
No Plaque, disease-free condition; NCP, exclusively noncalcified plaque; CP, exclusively calcified plaque; Mixed, mixed plaque; O1, Observer 1 (columns); O2, Observer 2 (rows).
Values in diagonals represent number of patients without differences between both observers.
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Influence of CV Risk Factors
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Discussion
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Limitations
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Conclusion
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Supplementary Data
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Table S1
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