Pathophysiology and clinical implications of pulmonary arterial enlargement in COPD

Figures & data

Figure 1 Potential mechanisms leading to relative pulmonary arterial enlargement in COPD.

Abbreviations: COPD, chronic obstructive pulmonary disease; PA:A, pulmonary artery to ascending aorta.

Table 1 Interobserver and intraobserver agreement in measuring the pulmonary artery and the PA:A ratio

Reference	Interobserver	Intraobserver	Comment
Mahammedi et al^Citation61	0.28 mm (for PA)	0.17 mm (for PA)	Bland-Altman analysis
Boerrigter et al^Citation64	0.1 ± 0.1 mm (for PA)	0.1 ± 0.2 mm (for PA)	Bland-Altman analysis
Zylkowska et al^Citation74	0.12 mm (for PA)	–	Bland-Altman analysis
Truong et al^Citation57	0.92	0.96	Cohen’s kappa
Iyer et al^Citation70	0.82 (95% CI 0.68–0.97)	–	Cohen’s kappa
Wells et al^Citation7	0.75 (95% CI 0.67–0.82)	0.92 (95% CI 0.83–1.0)	Cohen’s kappa

Abbreviations: CI, confidence interval; PA, pulmonary artery; PA:A, pulmonary artery to ascending aorta.

Figure 2 Measurement of the pulmonary artery (PA) and ascending aorta (A) diameters at the level of the PA bifurcation. PA diameter = line (A) (43.0 mm) and A diameter = average of lines (B) + (C) (39.6 mm) result in a PA:A ratio >1.

Table 2 Reference values for pulmonary artery diameter and PA:A ratio

Reference	Total subjects (n)	COPD subjects (%)	CT metric	Range
Lin et al^Citation62	103	0	PA	2.5 (1.9–3) cm
			PA:A	0.89 (0.66–1.13)
Truong et al^Citation57	3,171	159 (5.5%)	PA (male)	2.60 ± 0.27 cm*
			PA:A (male)	0.77 ± 0.09*
			PA (female)	2.42 ± 0.27 cm*
			PA:A (female)	0.76 ± 0.09*
			PA:A (COPD)	0.75 ± 0.09*

Note:

* P<0.01.

Abbreviations: PA, pulmonary artery; PA:A, pulmonary artery to ascending aorta; COPD, chronic obstructive pulmonary disease; CT, computed tomography.

Table 3 Correlation between PA diameter measured by CT, PA:A ratio, and hemodynamics

Reference	Study population, n	COPD subjects (%)	CT metric	Endpoint	Results
Ng et al^Citation63	50 (heterogeneous)	8 (16%)	PA	mPAP	r=0.74*
				PVR	r=0.55*
			PA:A	mPAP	r=0.74*
				PVR	r=0.59*
Mahammedi et al^Citation61	298 (heterogeneous)	17 (5.7%)	PA	mPAP	r=0.51*
			PA:A	mPAP	r=0.54*
Boerrigter et al^Citation64	69 (PAH)	0	PA	mPAP	r=0.58*
			PA:A	mPAP	r=0.71*
Devaraj et al^Citation68	77 (heterogeneous)	5 (6%)	PA	mPAP	r^2=0.45*
			PA:A	mPAP	r^2=0.45*
			PA:A + RVSP	mPAP	r^2=0.55*
Chan et al^Citation69	108 (hospitalized)	2 (2%)	PA >29 mm	mPAP >25 mmHg	OR 4.8*
			PA:A >1	mPAP >25 mmHg	OR 9.1*
Devaraj et al^Citation65	30 (ILD)	–	PA	mPAP	r=0.23
			PA:A	mPAP	r=0.54**
	47 (heterogeneous)	5 (10.6%)	PA	mPAP	r=0.67*
			PA:A	mPAP	r=0.72*
Zisman et al^Citation66	65 (IPF)	0	PA	mPAP	r=0.148
			PA:A	mPAP	r=0.203
Alhamad et al^Citation67	100 (ILD)	–	PA	mPAP	r=0.301*
			PA:A	mPAP	r=0.434*
	34 (heterogeneous)	8 (23.5%)	PA	mPAP	r=0.701*
			PA:A	mPAP	r=0.626*
Heinrich et al^Citation73	60 (CTEPH)	0	PA	mPAP	r=0.42*
			PA:A	mPAP	r=0.48*
				PVR	r=0.29**
Iyer et al^Citation70	60 (COPD)	100%	PA	mPAP	r=0.60*
			PA:A	mPAP	r=0.56*

Notes:

* P<0.01;

** P<0.05.

Abbreviations: mPAP, mean pulmonary artery pressure; PVR, pulmonary vascular resistance; r, Pearson correlation coefficient; PAH, pulmonary arterial hypertension; ILD, interstitial lung disease; IPF, idiopathic pulmonary fbrosis; CTEPH, chronic thromboembolic pulmonary hypertension; OR, odds ratio; COPD, chronic obstructive pulmonary disease; PA, pulmonary artery; PA:A, pulmonary artery to ascending aorta; CT, computed tomography.

Table 4 Utility of the PA:A ratio in diagnosis of pulmonary hypertension

Reference	PA:A value	Endpoint	Sensitivity	Specificity	PPV	NPV
Ng et al^Citation63	>1	mPAP >20 mmHg	70	92	96	52
Mahammedi et al^Citation61	>1	mPAP >25 mmHg	70.8	76.5	–	–
Boerrigter et al^Citation64	>1	mPAP >25 mmHg	92	72	–	–
Devaraj et al^Citation68	Composite value >25#	mPAP >25 mmHg	96	59	–	–
Chan et al^Citation69	>1	mPAP >25 mmHg	86.8	79.2	–	–
Alhamad et al^Citation67	>0.94 (non-ILD group)	mPAP >25 mmHg	68.4	80	81.2	66.6
Iyer et al^Citation70	>1	mPAP >25 mmHg	73	84	73	84

Note:

# estimated mPAP =23.6*PA:A + 0.34*RVSP −8.3.

Abbreviations: PPV, positive predictive value; NPV, negative predictive value; mPAP, mean pulmonary artery pressure; ILD, interstitial lung disease; PA:A, pulmonary artery to aortic; RVSP, right ventricular systolic pressure.

Figure 3 Scatter plots show relationships between mPAP and (A) PA:A ratio (n=60, r=0.55, P<0.001) and (B) echo-derived PASP (n=38, r=0.33, P=0.04).

Abbreviations: mPAP, mean pulmonary artery pressure; PA:A, pulmonary artery to ascending aorta; PASP, pulmonary artery systolic pressure.

Table 5 Outcomes related to PA:A ratio

Reference	Study population, n	CT metric	Outcome	Results
Nakanishi et al^Citation71	1,326 (healthy patients)	PA:A >0.9	Mortality	HR 3.2 (1.6–6.6)*
Baptista et al^Citation72	39 (acute PE)	PA	Mortality	NS
		PA:A	Mortality	NS
wells et al^Citation7	3,464 (COPD)	PA:A >1	Severe AECOPD	OR 3.44 (2.78–4.25)*
			Any AECOPD	OR 1.86 (1.54–2.24)*
	2,005 (COPD)	PA:A >1	Severe AECOPD (one year)	OR 2.8 (2.11–3.71)*
			Any AECOPD (one year)	OR 2.17 (1.71–2.74)*
			Severe AECOPD (3 years)	OR 3.81 (3.04–4.78)*
			Any AECOPD (3 years)	OR 6.68 (4.47–9.96)*

Note:

* P<0.01.

Abbreviations: AECOPD, acute exacerbation of chronic obstructive pulmonary disease; CT, computed tomography; HR, hazards ratio; OR, odds ratio; PE, pulmonary embolism; PA:A, pulmonary artery to aortic; NS, not statistically significant; COPD, chronic obstructive pulmonary disease.

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