Rationale and Objectives
To document the prevalence of coronary artery disease (CAD) and major adverse cardiac events (MACE) in patients younger than 45 years of age with intermediate pretest likelihood of CAD, and to determine whether coronary computed tomography angiography (cCTA) is useful for risk stratification of this cohort.
Materials and Methods
We followed 452 intermediate pretest likelihood (according to Diamond and Forrester) outpatients who were suspected of CAD and underwent cCTA. They were all younger than 45 years old. The endpoint was MACE, defined as composite cardiac death, nonfatal myocardial infarction, or coronary revascularization.
Results
Follow-up was completed in 427 patients (94.5%) with a median follow-up period of 1081 days. No plaque was noted in 357 (83.6%) patients. Nonsignificant CAD was noted in 33 (7.7%) individuals and 37 (8.7%) patients with significant CAD. At the end of the follow-up period, 12 (2.8%) patients experienced MACE. The annualized event rate was 0.2% in patients with no plaque, 2.0% in patients with nonsignificant CAD, and 7.3% in patients with significant CAD. Hypertension, smoking, and significant CAD in cCTA were significant predictors of MACE in univariate analysis. Moreover, cCTA remained a predictor ( P < .001) of events after multivariate correction (hazard ratio: 8.345, 95% CI: 3.438–17.823, P < .001).
Conclusion
The prevalence of CAD and MACE in young adults with an intermediate pretest likelihood of CAD was considerable. cCTA is effective in restratifying patients into either a low or high posttest risk group. These results further emphasize the usefulness of cCTA in this cohort.
Coronary artery disease (CAD) remains a leading cause of global mortality despite significant medical advances during the past several decades . CAD predominantly manifests in older individuals and is closely related with age . Most studies have shown that only about 3% of all CAD cases and 2% to 6% of all infarctions involve individuals under the age of 45 . Prior studies have demonstrated the utility of coronary computed tomography angiography (cCTA) in symptomatic patients with a low- to intermediate-pretest probability of significant CAD, and suggest that cCTA does not provide additional relevant diagnostic information in patients with a high estimated pretest probability of CAD . Few studies have specifically evaluated cCTA in a young patient population with an intermediate pretest likelihood. The purpose of this study was to document the prevalence of CAD and major adverse cardiac events (MACE) in patients younger than 45 years of age with intermediate pretest likelihood of CAD, and to determine whether cCTA is useful for risk stratification of this cohort.
Materials and methods
Patient Recruitment
We evaluated 463 consecutive patients younger than age 45 who underwent cCTA between January 2007 and August 2008. The cCTA was performed to exclude CAD in patients at intermediate pretest likelihood of CAD according to Diamond and Forrester criteria , which are based on age, gender, and symptomatic status (including typical angina, atypical angina, non-anginal chest pain, and asymptomatic). Intermediate likelihood was defined as a pretest likelihood between 13.4% and 87.2%. In addition, asymptomatic diabetic patients were also classified as having an intermediate pretest likelihood according to the increased prevalence of CAD and increased risk of events in this population . For the present study, we excluded subjects with a history of acute myocardial infarction (AMI) ( n = 2), inadequate image quality because of motion artifacts or inadequate contrast concentration ( n = 5), or have other heart diseases (cardiomyopathy n = 1, valvular heart disease n = 1, congenital heart disease n = 2). Eventually, 452 intermediate pretest likelihood patients (284 men and 168 women) were enrolled.
Imaging Protocols
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Image Analysis
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CAD Risk Factors Assessment
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Follow-up
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Statistical Analysis
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Results
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Table 1
The Baseline Characteristics for All the Patients
Characteristics Overall ( n = 427) Plaque ( n = 70 ) No Plaque ( n = 357)P Value Age (y) 40.6 ± 3.9 42.1 ± 1.8 40.3 ± 4.1 <.001 Male 265 (62.1%) 49 (70.0%) 216 (60.5%) <.001 Body mass index 26.3 ± 4.5 27.0 ± 3.6 26.1 ± 4.7 .169 Obesity 45 (10.5%) 9 (12.9%) 36 (10.1%) .490 Hypertension 183 (42.9%) 46 (65.7%) 137 (38.4%) <.001 Diabetes 134 (31.4%) 30 (42.9%) 104 (29.1%) <.001 Dyslipidemia 112 (27.0%) 21 (30.0%) 91 (25.5%) .433 Family history 170 (39.8%) 37 (52.9%) 133 (37.3%) <.001 Smoking 199 (46.6%) 34 (48.6%) 165 (46.2%) .718
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Table 2
The Prevalence of CAD and MACE
n (Percentage) MACE (Rate)P Value Calcified plaque 66 (19.0%) 1 (1.5%) Noncalcified plaque 133 (38.0%) 3 (2.3%) Mixed plaque 151 (43.0%) 6 (4.0%) .527 CACS = 0 375 (87.8%) 5 (1.3%) CACS 1–100 46 (10.8%) 6 (13.0%) CACS 101–400 6 (1.4%) 1 (16.7%) <.001 No plaque 357 (83.6%) 2 (0.56%) Nonsignificant CAD 33 (7.7%) 2 (6.06%) Significant CAD 37 (8.7%) 8 (21.6%) <.001
CACS, coronary artery calcium score; CAD, coronary artery disease; MACE, major adverse cardiac events.
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Table 3
The Prevalence of Significant CAD and MACE in Each Subgroup Based upon Presenting Symptoms
Without Typical Angina Typical Angina χ²P Value Asymptomatic Nonanginal CP Atypical Angina χ²P Value_n_ ( n /427) 128 (30.0%) 205 (48.0%) 68 (15.9%) 26 (6.1%) Significant CAD 8 (6.3%) 14 (6.8%) 5 (7.4%) 0.092 .955 10 (38.5%) 31.058 <.001 MACE 3 (2.3%) 4 (2.0%) 1 (1.5%) 0.177 .915 4 (15.4%) 16.027 <.001
CAD, coronary artery disease; CP, chest pain; MACE, major adverse cardiac events.
Table 4
Univariate and Multivariate Predictors of MACE
Univariate Analysis Multivariate Analysis HR (95% CI)P Value HR (95% CI)P Value Age 1.110 (0.904–1.363) .319 Male 0.649 (0.206–2.045) .460 Hypertension 1.601 (1.220–2.096) .001 Family history 1.097 (0.348–3.456) .875 Dyslipidemia 1.130 (0.914–1.673) .265 Diabetes 1.423 (0.531–5.059) .478 Obesity 2.654 (0.719–9.805) .343 Smoking 1.645 (1.220–2.128) <.001 Significant CAD 10.137 (3.469–36.715) <.001 8.345 (3.438–17.823) <.001
CAD, coronary artery disease; MACE, major adverse cardiac events.
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Discussion
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