Coronary Artery Plaque Characteristics Associated With Adverse Outcomes in the SCOT-HEART Study

Abstract

Background: Unlike most noninvasive imaging modalities, coronary computed tomography angiography can characterize subtypes of atherosclerotic plaque.

Objectives: The purpose of this study was to investigate the prognostic implications of adverse coronary plaque characteristics in patients with suspected coronary artery disease.

Methods: In this SCOT-HEART (Scottish COmputed Tomography of the HEART Trial) post hoc analysis, the presence of adverse plaque (positive remodeling or low attenuation plaque), obstructive disease, and coronary artery calcification within 15 coronary segments was assessed on coronary computed tomography angiography of 1,769 patients who were followed-up for 5 years.

Results: Among study participants (mean age 58 ± 10 years; 56% male), 608 (34%) patients had 1 or more adverse plaque features. Coronary heart disease death or nonfatal myocardial infarction was 3 times more frequent in patients with adverse plaque (n = 25 of 608 [4.1%] vs. n = 16 of 1,161 [1.4%]; p < 0.001; hazard ratio [HR]: 3.01; 95% confidence interval (CI): 1.61 to 5.63; p = 0.001) and was twice as frequent in those with obstructive disease (n = 22 of 452 [4.9%] vs. n = 16 of 671 [2.4%]; p = 0.024; HR: 1.99; 95% CI: 1.05 to 3.79; p = 0.036). Patients with both obstructive disease and adverse plaque had the highest event rate, with a 10-fold increase in coronary heart disease death or nonfatal myocardial infarction compared with patients with normal coronary arteries (HR: 11.50; 95% CI: 3.39 to 39.04; p < 0.001). However, these associations were not independent of coronary artery calcium score, a surrogate measure of coronary plaque burden.

Conclusions: Adverse coronary plaque characteristics and overall calcified plaque burden confer an increased risk of coronary heart disease death or nonfatal myocardial infarction. (Scottish COmputed Tomography of the HEART Trial [SCOT-HEART]; NCT01149590).

Keywords: atherosclerotic plaque; computed tomography; coronary angiography; coronary artery disease.

Graphical abstract

Figure 1

Coronary Plaque Characteristics Identified on Computed Tomography Coronary Angiography Coronary atherosclerotic plaque features detected using computed tomography coronary angiography including (A) positive remodeling, (B) low-attenuation plaque, (C) spotty calcification, and (D) the “napkin ring” sign. Positive remodeling (A) was defined as an outer vessel diameter (long dashed line) that was 10% greater than the mean diameter of the segments immediately proximal (short dashed line) and distal to the plaque. Low-attenuation plaque (B) was defined as a focal central area of plaque with an attenuation density of <30 Hounsfield Units (yellow arrow). Spotty calcification (C) was defined as focal calcification within the coronary artery wall that measured <3 mm in maximum diameter (yellow arrow). The “napkin ring” sign (D) was defined as a central area of low-attenuation plaque with a peripheral rim of high attenuation (yellow arrow).

Figure 2

Coronary Heart Disease Death or Nonfatal Myocardial Infarction Across the Total Cohort in Patients With and Without Adverse Plaque The effect of the presence of 1 or more adverse plaques (defined by the presence of low attenuation or positive remodeling) on subsequent coronary heart disease (CHD) death or nonfatal myocardial infarction (MI). Cumulative incidence plot for patients with and without adverse plaque features.

Figure 3

Coronary Heart Disease Death and Nonfatal Myocardial Infarction in Patients With Different Stenosis Severity and Coronary Artery Plaque Characteristics Cumulative incidence plot for coronary heart disease death and nonfatal myocardial infarction in patients (top) with normal coronary arteries, nonobstructive disease, and obstructive disease and in (bottom) normal coronary arteries, nonobstructive disease with and without adverse plaque characteristics, and obstructive disease with and without adverse plaque features. AP = adverse plaque; other abbreviations as in Figure 2.

Figure 4

Coronary Heart Disease Death or Nonfatal Myocardial Infarction in Patients With Different Severity of Coronary Artery Calcification Cumulative incidence plots of the effect of different severity of coronary artery calcification on subsequent coronary heart disease death or nonfatal myocardial infarction. Abbreviations as in Figure 2.

Central Illustration

Adverse Plaque on Computed Tomography Coronary Angiography Identifies Patients at an Increased Risk of Subsequent Events (A) Bar graph of the frequency of coronary heart disease death or nonfatal myocardial infarction at 2 and 5 years for patients with normal coronary arteries and nonobstructive or obstructive disease with and without adverse plaque. (B) Coronary computed tomography angiography and invasive coronary angiography images from a patient with nonobstructive coronary artery disease who had a subsequent non–ST-segment elevation myocardial infarction. The red/yellow dotted lines and arrows correspond to the location of the plaques in the red/yellow boxes.