CT coronary angiography in low- to intermediate-risk patients: Less radiation, less invasive angiography, and less revascularisation

Figures & data

Figure 1. Stenosis in the left anterior descending branch (arrow) diagnosed on CT coronary angiography (left) and invasive coronary angiography (right).

Table I. Characteristics in relation to demographics, clinical data, CT coronary angiography, and follow-up.

	Year
Characteristic	2010 (n = 596)	2011 (n = 841)	2012 (n = 1147)	2013 (n = 957)	Test for trend*
Age (years)	59 (44–73)	60 (44–73)	60 (44–72)	59 (44–71)	0.284
Men	47.0	47.4	44.6	45.0	0.252
Height (cm)	171 (160–185)	172 (161–185)	172 (160–184)	171 (160–184)	0.881
Weight (kg)	78 (61–99)	80 (60–100)	78 (60–100)	77 (60–101)	0.527
Body mass index (kg/m^2)	25.7 (21.9–32.4)	26.2 (21.4–33.2)	26.2 (21.4–32.6)	26.0 (21.5–32.6)	0.685
Smoking					0.253
Never	39.8	40.9	41.5	39.4
Former	36.3	35.9	38.2	40.9
Current	23.9	23.3	20.3	19.7
Systolic blood pressure (mm Hg)	134 (114–162)	138 (116–165)	135 (115–162)	136 (116–161)	0.809
Diastolic blood pressure (mm Hg)	80 (66–94)	82 (69–95)	81 (70–95)	82 (70–94)	0.117
Medical treatment for hypertension	38.1	39.9	40.0	37.4	0.698
Left ventricular ejection fraction	60 (60–65)	60 (60–65)	60 (60–65)	60 (60–60)	0.002
Plasma creatinine (μ mol/l)	73 (56–94)	73 (56–95)	72 (57–93)	74 (59–94)	0.259
Diabetes mellitus	8.3	9.7	7.5	5.7	0.011
Cholesterol lowering treatment	37.6	34.8	33.7	31.2	0.009
Family history of ischaemic heart disease	47.8	45.6	52.1	50.8	0.043
CT coronary angiography
Volume of contrast (ml)	75 (60–90)	80 (60–90)	60 (60–90)	60 (60–90)	< 0.001
Radiation dose (mSV)	4.2 (1.8–10.5)	3.8 (2.6–8.8)	2.4 (1.2–5.1)	2.2 (1.2–4.8)	< 0.001
Calcium score (Hounsfield units)	6 (0–722)	2 (0–746)	5 (0–579)	6 (0–527)	0.728
Consequence of CT angiography
Referred to coronary angiography	25.3	21.0	23.0	10.8	< 0.001
Referred to perfusion scan	2.8	2.1	2.8	10.0	< 0.001
Proportion having coronary angiography, percutaneous coronary revascularisation or coronary bypass surgery during follow-up					**
Coronary angiography	29.2	25.2	24.0	16.0
Percutaneous coronary intervention	8.4	7.0	5.8	4.7
Coronary bypass surgery	2.0	2.7	2.4	1.6

Medians with 10th and 90th percentiles in brackets for continuous variables. Percentage for categorical variables.

* Test for trend for categorical variables in 2*c eller r*c table. Trend test for continuous variables used non-parametric correlation analysis.

**Statistical test not done because of truncated observation time. Please refer to Cox regression model in Table II.

Table II. Cox proportional hazard ratios with 95% confidence interval in brackets for the associations between year of CT coronary angiography and use of invasive coronary angiography and coronary revascularisation.

Year of CT coronary angiography	Hazard ratio (95% confidence interval) for invasive coronary angiography after CT coronary angiography
	Unadjusted	Age- and sex-adjusted	Multivariable adjusted*
2010 (reference)	1	1	1
2011	0.88 (0.72–1.08)	0.84 (0.68–1.02)	0.86 (0.69–1.05)
2012	0.83 (0.69–1.01)	0.82 (0.68–1.00)	0.85 (0.70–1.04)
2013	0.56 (0.45–0.69)	0.56 (0.45–0.69)	0.59 (0.47–0.74)

	Hazard ratio (95% confidence interval) for coronary revascularisation after CT coronary angiography
	Unadjusted	Age- and sex-adjusted	Multivariable adjusted*
2010 (reference)	1	1	1
2011	0.89 (0.63–1.25)	0.83 (0.59–1.16)	0.85 (0.60–1.21)
2012	0.78 (0.57–1.11)	0.80 (0.58–1.12)	0.85 (0.61–1.12)
2013	0.63 (0.44–0.90)	0.64 (0.45–0.92)	0.66 (0.45–0.97)

*Adjusted for age, sex, cholesterol lowering treatment, and diabetes mellitus.

Figure 2. Cumulative proportion of the use of invasive coronary angiography by year of first CT coronary angiography.

Figure 3. Cumulative proportion of coronary revascularisation by year of first CT coronary angiography.