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Keywords:

  • atrium;
  • pulmonary heart disease;
  • thrombosis;
  • tomography

Summary.

  1. Top of page
  2. Summary.
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Disclosure of Conflict of Interests
  8. References

Background: Early identification by computed tomography pulmonary angiography (CTPA) of patients with acute pulmonary embolism (PE) who have signs associated with a high embolic burden would be highly desirable. Objectives: To investigate whether an increased obstruction of the pulmonary vasculature is associated with reduced left atrial (LA) and increased right atrial (RA) areas. Methods: We retrospectively analyzed a consecutive series of CTPA studies of 137 patients with acute PE and 38 controls without PE between October 2004 and March 2006. Left and right atrial areas and longitudinal and short axis diameters were measured and correlated with the pulmonary arterial obstruction index (PAOI) divided into tertiles (obstruction of < 12.5%, 12.5%–42.5% and ≥ 42.5%). Results: There was a significant negative age- and gender-adjusted correlation between the PAOI and LA measurements, particularly the LA area (r = −0.259) and the LA short axis diameter (r = −0.331). All RA measurements had positive correlations (RA area, r = 0.279; RA short axis diameter, r = 0.313). The LA/RA area ratio correlated negatively with the PAOI (r = −0.447). All above-mentioned correlations had P < 0.002. All the LA measurements were the largest in the controls and gradually decreased with higher PAOIs. A receiver operating characteristic curve analysis demonstrated that the RV/LV diameter, LA/RA area and LA/RA short axis diameter ratios had comparable discriminative ability for higher PAOI tertiles. Conclusions: The higher the clot load in the pulmonary arteries, the smaller the LA area and the larger the RA area. Atrial area measurements by CTPA may serve as a real-time parameter in assessing the severity of PE upon diagnosis.


Introduction

  1. Top of page
  2. Summary.
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Disclosure of Conflict of Interests
  8. References

Computed tomography pulmonary angiography (CTPA) is currently the modality of choice for the diagnosis of acute pulmonary embolism (PE) [1,2]. Determination of its role in the early identification of patients who are at increased risk of subsequent development of circulatory collapse due to acute right heart failure is, however, still ongoing [3]. The most widely accepted approach is that right ventricular dysfunction can be evaluated in PE patients by measuring the diameters of the right (RV) and left (LV) ventricles [4–8]. In addition, the clot load within the pulmonary tree can be assessed by calculating the pulmonary arterial obstruction index (PAOI) [4,5,8–13]. A recently published report on three patients suffering from massive acute PE, each carrying an embolic load of > 50%, showed a reduction in left atrial (LA) volume during the acute event compared with the LA volume calculated from CTs obtained earlier or following treatment [14]. In addition, increased clot load leading to RV dysfunction might be associated with a backward increase in RA volume. There are no earlier publications of studies on any association between the severity of a pulmonary arterial obstruction and atrial size as measured on CTPA. Because the presence of a reduced LA size during a severe acute PE may serve as an additional early parameter in assessing the severity of the PE, our aim was to examine whether an increased obstruction of the pulmonary vasculature in patients with acute PE is associated with smaller LA and larger RA areas.

Materials and methods

  1. Top of page
  2. Summary.
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Disclosure of Conflict of Interests
  8. References

Study population

The institutional review board approved this retrospective study with a waiver of informed consent. We took advantage of a previously reported cohort [15] and retrospectively studied 190 patients who were investigated for possible PE by CTPA at our center. Fifteen patients with incomplete CTPA, clinical or survival data were excluded, leaving a total study cohort of 137 consecutive patients with PE on CTPAs performed between 1 October 2004 and 31 March 2006, and a control group that was comprised of 38 consecutive patients with CTPAs that were negative for PE (15 December 2004 and 11 February 2005). Patients with multiple scans were entered once into our analysis according to their primary CTPA results. Referral for CTPA studies was based on clinical suspicion of acute PE by the referring physicians. CTPA is performed at our institution within 12 h of presentation, while the initiation of treatment before CTPA depends upon the degree of clinical suspicion and the patient’s status.

CT acquisition

All patients were scanned by a multi-detector CT scanner (M×8000 IDT or Brilliance; Philips Medical Systems, Cleveland, OH, USA) acquiring 10, 16, 40 or 64 detectors. Reconstructed slice thickness was 1.0–2.0 mm, with an increment of 0.5–1 mm. The PE protocol consisted of contrast injections of 100–120 mL of iodinated contrast material at a concentration of 300 mg iodine mL−1 (Ultravist; Schering, Berlin, Germany) at rates of 3–4 mL s−1. All scans were obtained in a caudal-cranial direction at end-of-inspiration during a single breath-hold.

CT assessment

The LA and RA dimensions were measured by two senior radiologists (G.A and G.R.), one of them fellowship trained in thoracic imaging and the other a radiologist with fellowship training in vascular imaging, and with 10 and 8 years of experience, respectively. They were unaware of the patients’ clinical history, results of other imaging techniques, and outcome. Using the Radiology PACS workstation (Centricity 2.1.2.1; GE Health Care, Milwaukee, WI, USA), both radiologists calculated the LA and RA areas from planimetric measurements obtained from free-hand delineation of the atrial boarders using an electronic pen. Because there are no established methods or reference values for quantitative volumetric measurements of RA on CT, and given the limited data on LA measurements [16,17], we chose to obtain our measurements from the original axial images. Assessment of both atria was performed by scrolling through the images of each atrium at the level of its atrioventricular valve. The axial image chosen for all measurements was the one where the atrium was visually estimated to be at its maximal area. Thus, the borders of the LA were defined on the axial slice where the LA area was visually maximal and the mitral valve could be identified. The pulmonary veins were excluded from measurement of the LA area by placing the line of the planimetric border across the pulmonary venous ostium at the atriopulmonary venous junction. The axial longitudinal diameter (defined as the distance between an imaginary line across the hinge point of the mitral valve anteriorly and the posterior LA wall) as well as the axial short axis diameter perpendicular to it (defined as the distance between the inter-atrial septum and the posterior LA wall) were also measured by electronic calipers on the same axial image. RA borders were defined on the axial slice where the RA area was maximal and the tricuspid valve could be identified or presumed to be located. The axial longitudinal diameter (defined as the distance between the line across the hinge point of the tricuspid valve anteriorly and the posterior RA wall) as well as the axial short axis diameter perpendicular to it (defined as the distance between the inter-atrial septum and the anterior RA wall) were measured by electronic calipers on the same axial image. Figure 1 shows an example of atrial measurements. Both radiologists performed atrial measurements on the same axial slices independently in order to determine inter-observer variations.

image

Figure 1.  Measurements of the left and right atria in a 56-year-old male with severe acute pulmonary embolism (arrows) and a pulmonary arterial obstruction index of 33 (obstruction of 82% of the pulmonary tree). (A) Left atrium (LA). The borders of the LA were defined on the axial slice where the LA area was visually maximal and the mitral valve could be identified or presumed to be present. The LA area was measured by planimetry (solid free hand line = 22.3 cm2). The axial longitudinal diameter (dashed line = 6.7 cm) was defined as the distance between an imaginary line across the hinge point of the mitral valve anteriorly and the posterior LA wall. The axial short axis diameter was measured perpendicular to it (dotted line = 4.4 cm) between the inter-atrial septum and the posterior LA wall. (B) Right atrium (RA). The borders of the RA were defined on the axial slice where the RA area was maximal and the tricuspid valve could be identified or presumed to be. The RA area was measured by planimetry (solid free hand line = 38.5 cm2). The axial longitudinal diameter (dashed line = 6.4 cm) was defined as the distance between the line across the hinge point of the tricuspid valve anteriorly, and the posterior RA wall. The axial short axis diameter was measured perpendicular to it (dotted line = 7.0 cm), between the inter-atrial septum and the anterior RA wall. LA = left atrium; RA = right atrium; PAOI = pulmonary arterial obstruction index.

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RV and LV diameters were also measured by identifying the maximal distance between the ventricular endocardium and the interventricular septum perpendicular to the long axis in four chamber views reconstructed by using two-dimensional multiplanar reformats (MPRs). The presence or absence of PE on the CTPA studies, the RV and LV diameters on a four-chamber reformat and PE clot load score were assessed on a dedicated workstation (MxView; Philips Medical Systems) and collected from our previous report [15].

The presence and location of arterial clots as well as the degree of arterial obstruction were scored using the system proposed by Qanadli et al. [12] and reported previously by our group [15]. Briefly, this scoring system includes 20 segmental pulmonary artery branches. Emboli more proximal to a segmental level are given a score equal to the number of segmental branches arising distally. Each segmental score receives an additional weighting factor for the degree of luminal obstruction (0 = no embolic material, 1 = partial branch obstruction, 2 = complete branch occlusion). Thus, the maximal obstruction index is 40 per patient, which is equivalent to obstruction of 100%.

Clinical information

In addition to gender and age the charts were reviewed for background and comorbid conditions, including obesity, diabetes mellitus, hypertension, dyslipidemia, current smoking, chronic obstructive pulmonary disease (COPD), asthma, congestive heart failure and ischemic heart disease. Admission to an intensive care unit (ICU) within 30 days of PE diagnosis was also recorded. The 30-day mortality was collected from the database of the country’s Ministry of Internal Affairs. The probable cause of in-hospital mortality was determined by two senior physicians in internal medicine after carefully reviewing all available data.

Statistical analysis

Data were summarized as mean ± standard deviation (SD) for continuous variables, and as number of individuals for categorical variables. Kappa was calculated in order to measure agreement between the two independent observers for all atrial measurements divided into quartiles. Pearson’s correlation was used to evaluate the correlation between age and PAOI and LA and, RA measurements, as well as LA/RA ratios. Student’s t-test was used to evaluate gender differences in all parameters. Linear regression models were used to calculate age- and gender-adjusted partial correlations between the PAOI and the different LA and RA and ventricular measurements. In order to further quantitate the differences in the atrial and ventricular measurements between the levels of PAOI and the controls, we divided the group of patients with PE into tertiles based on their PAOI and calculated the age- and gender-adjusted estimated marginal means using general linear models. Because LA/RA ratios did not correlate with age or demonstrate any persistent gender differences, their correlations were not adjusted to age or gender. Furthermore, in order to evaluate the performance of classification schemes for the different measurements and to compare their classification ability into the higher tertiles of PAOI, we used a receiver operating characteristic (ROC) curve analysis. DeLong and DeLong’s method was used to compare ROC curves between the different measurements. We calculated the area under the curve to compare the classifiers and determine the cut-off that achieves 90% sensitivity along with the corresponding specificity. All the above analyses were considered significant at < 0.05 (two-tailed). The SPSS statistical package was used to perform all statistical evaluations (SSPS Inc., Chicago, IL, USA).

Results

  1. Top of page
  2. Summary.
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Disclosure of Conflict of Interests
  8. References

There were 47 males and 90 females with PE, who had a mean age of 67 ± 19 years (range 22–96). The control group included 12 males and 26 females, who had a mean age of 68 ± 18 years (range 21–88). The age difference of the two groups was not significant (= 0.610). The baseline characteristics of the study cohort are presented in Table 1. There were more patients with asthma or COPD as well as hypertension and dyslipidemia in the control group than among the patients with PE.

Table 1.   Characteristics of patients with PE and controls
 PE (= 137)Controls (= 38)P value
n%n%
  1. COPD, chronic obstructive pulmonary disease.

Female gender906626680.847
Obesity54000.358
Diabetes mellitus13106160.375
Hypertension342521550.001
Dyslipidemia161212320.006
Current smoker4313> 0.999
COPD/asthma649240.001
Congestive heart failure5425> 0.999
Ischemic heart disease1187180.074

We found substantial agreement between the two independent observers for the LA long and short axis diameter and the RA long diameter measurements (κ = 0.47–0.52), and an even higher agreement (κ = 0.73–0.84) for the LA and RA areas, as well as for the RA short axis diameter.

Significant gender and age associations were noted for all atrial measurements, but not for the ratios of left to right atria (data not shown). Therefore all subsequent atrial analyses were age and gender adjusted. Table 2 presents the correlation between the PAOI and the atrial and ventricular measurements. There was a significant negative correlation between the PAOI and all LA measurements, particularly those of the LA area and LA short axis diameter, while all RA measurements were positively correlated with the PAOIs. Consequently, LA/RA area ratios yielded the greatest negative correlation with the PAOI among all the atrial measurements. We further divided our sample into tertiles based on PAOIs: PAOI < 5 (obstruction of < 12.5%), 5 ≤ PAOI < 17 (obstruction of 12.5–42.5%), and PAOI ≥ 17 (obstruction of > 42.5%), and compared the various measurements between the three tertiles and the controls. Age- and gender-adjusted estimated marginal means for all measurements in each tertile and controls are displayed in Table 3. All the LA measurements were smallest for the group with the highest PAOIs, and the values gradually increased as the PAOIs became smaller. All the LA measurements were highest in the control group. The RV to LV diameter ratio showed no significant difference between the control group and the two lower PAOI tertiles, while the value for that ratio for the group of patients with large PE was significantly higher. Analyzing the less severely ill patients (e.g. those in the two lower PAOI tertiles) and the controls, while excluding the patients in the highest PAOI tertile, revealed that the left atrial area was the only parameter to demonstrate a significant difference between those groups (= 0.021), and that there was no significant difference in the RV to LV diameter ratio between those groups.

Table 2.   Partial correlation* between PAOI and atrial and ventricular measurements
 LA areaLA long. diam.LA short axis diam.
  1. LA, left atrium; RA, right atrium; PAOI, pulmonary arterial obstruction index; long., longitudinal; diam., diameter; RV, right ventricle; LV, left ventricle. *Left and right atrial and ventricular estimations are age and gender adjusted. No adjustment was done for LA/RA ratios.

PAOI
 r−0.256−0.144−0.327
 P0.0030.096< 0.001
 RA areaRA long. diam.RA short axis diam.
PAOI
 r0.2760.2040.309
 P0.0010.017< 0.001
 LA/RA area ratioLA/RA long. diam. ratioLA/RA short axis diam. ratio
PAOI
 r−0.447−0.246−0.453
 P< 0.0010.004< 0.001
 RV diam.LV diam.RV/LV ratio
PAOI
 r0.457−0.4240.653
 P< 0.001< 0.001< 0.001
Table 3.   Estimated marginal means (95% CI) of the different atrial and ventricular measurements in PAOI tertiles*
Atrial measurementsControlsPAOI < 5 (obstruction < 12.5%)5 ≤ PAOI < 17 (12.5% ≤ obstruction < 42.5%)PAOI ≥ 17 (obstruction ≥ 42.5%)P value
Mean95% CIMean95% CIMean95% CIMean95% CI
  1. LA, left atrium; RA, right atrium; PAOI, pulmonary arterial obstruction index; long., longitudinal; diam., diameter; RV, right ventricle; LV, left ventricle. *Left and right atrial and ventricular estimations are age and gender adjusted. No adjustment was done for LA/RA ratios. Pulmonary arterial obstruction index is expressed as a percentage of maximum score.

LA area (cm2)24.122.2–25.921.319.7–23.020.118.4–21.917.716.0–19.5< 0.001
LA long. diam. (cm)5.95.7–6.25.65.3–5.85.55.2–5.75.35.0–5.50.003
LA short axis diam. (cm)4.54.2–4.84.34.1–4.64.13.8–4.33.73.4–3.9< 0.001
RA area (cm2)22.620.5–24.820.718.8–22.520.018.0–22.024.422.4–26.30.007
RA long. diam. (cm)5.04.7–5.34.74.4–4.94.64.3–4.84.94.7–5.20.060
RA short axis diam. (cm)5.35.0–5.65.24.9–5.54.94.7–5.35.85.5–6.10.001
LA/RA area ratio1.101.01–1.181.061.00–1.141.081.00–1.160.760.68–0.84< 0.001
LA/RA long. diam. ratio1.231.16–1.311.211.15–1.281.231.16–1.301.091.02–1.150.008
LA/RA short axis diam. ratio0.890.82–0.950.860.80–0.910.850.79–0.910.650.59–0.70< 0.001
RV diam. (cm)4.03.7–4.23.73.5–3.93.83.6–4.04.44.2–4.6< 0.001
LV diam. (cm)4.13.9–4.44.24.0–4.44.13.9–4.33.63.3–3.8< 0.001
RV/LV diam. ratio0.980.90–1.060.890.82–0.970.940.86–1.011.311.23–1.38< 0.001

Table 4 presents the results of the ROC curve analysis on the ability of different cut-offs of the atrial measurements to identify individuals with a large clot burden, represented here as the upper PAOI tertile. The right to left ventricle diameter ratio, left to right atria area ratio and left to right atria short axis diameter ratio had the highest area under the curves, without significant difference between them using DeLong and DeLong’s analysis (> 0.6 for each), and all three measurements performed significantly better than all other atrial measurements (all < 0.03).

Table 4.   ROC curve analysis of the different atria and ventricular measurements for the higher PAOI tertile (obstruction of ≥ 42.5%)
 AUC95% CIP value90% Sensitivity
Cut-offSpecificity (%)
  1. LA, left atrium; RA, right atrium; long., longitudinal; diam., diameter; RV, right ventricle; LV, left ventricle.

LA area0.6590.568–0.7510.002< 22.036.3
LA long. diam.0.6090.510–0.7080.037< 6.314.3
LA short axis diam.0.6870.599–0.775< 0.001< 4.537.4
RA area0.6690.577–0.7610.001> 16.034.1
RA long. diam.0.5870.486–0.6880.098> 3.713.2
RA short axis diam.0.6940.606–0.781< 0.001> 4.533.0
LA/RA area ratio0.8210.747–0.894< 0.001< 1.0350.5
LA/RA long. diam. ratio0.6720.575–0.7680.001< 1.4117.6
LA/RA short axis diam. ratio0.8050.730–0.879< 0.001< 0.8248.4
RV diam.0.7610.677–0.845< 0.001> 3.535.2
LV diam.0.7180.626–0.810< 0.001< 4.629.7
RV/LV diam. ratio0.8280.746–0.910< 0.001> 0.8434.1

In addition to the area under the curve, we also report the cut-off that achieves 90% sensitivity and the corresponding specificity as displayed in Table 4. The highest discrimination at this point, with 90% sensitivity, was achieved by the left to right atrial area ratio and the left to right atrial short axis diameter ratio, while RV/LV ratio was less discriminative.

Twenty-three of all our 137 PE patients (17%) and four of the 38 controls (11%) died by the end of the 30 days of follow-up. Of the 23 PE patients who died, the cause of death was probably related to the PE in only eight (35%) of them, while the cause of death was most likely related to the background comorbidities or current acute illness in the other 15. Among those eight PE-related deaths, four were in the higher PAOI tertile, three in the middle tertile and only one in the lower PAOI tertile (= 0.12). In addition, only 10 of the 137 PE patients (7%) and two of the 38 controls (5%) were admitted to an ICU during the 30 days of follow-up. Three of those 10 PE patients were in the higher PAOI tertile, five were in the middle tertile and two were in the lower PAOI tertile (= 0.50). The small numbers of PE-related deaths and ICU admissions precluded our ability to analyze the parameters of PE mortality and ICU admissions in relation to the atrial and ventricular measurements.

Discussion

  1. Top of page
  2. Summary.
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Disclosure of Conflict of Interests
  8. References

The main finding of our study is that a higher clot load in the pulmonary arteries is associated with a smaller LA size and a larger RA size, as measured on CTPA studies. Moreover, the LA/RA area and short axis ratios were as capable of identifying severe obstruction as was the RV/LV diameter ratio, which is considered the most accepted parameter for severity assessment in patients with acute PE [4,5,7,8]. When comparing atrial and ventricular measurements with regard to patients with low clot burden (i.e. between the two lower PAOI tertiles and the controls), the left atrial area was the only parameter to demonstrate a significant difference, while RV/LV ratio did not. In addition, at the preselected clinically important point of 90% sensitivity, the atrial ratios demonstrated even better specificities compared with the RV/LV diameter ratio. The obtained interobserver agreement of our planimetric measurements of the atria yielded a higher value (κ = 0.73–0.84) than the unidimensional atrial diameters (κ = 0.47–0.52), which were similar to the interobserver agreement for ventricular diameters previously reported in the literature [9]. The significance of our study is its proposal of an additional parameter that reflects modifications in cardiac morphology in response to pulmonary arterial obstruction in patients with acute PE. Atrial assessment is rapid and easy and may therefore contribute to the establishment of CTPA as a useful tool for both the diagnosis of PE and the identification of those patients with cardiac morphological changes that are associated with a high embolic load who might be at risk of sudden circulatory collapse and, consequently, may be considered for closer monitoring, with possible thrombolytic therapy [3].

Pathophysiological studies have suggested that there is an increase in pulmonary vascular resistance due to the anatomical obstruction caused by the emboli, release of vasoconstricting agents and reflex hypoxemia during a major PE event [18]. This sudden increase in RV afterload results in elevated right ventricular wall tension, dilatation of the RV, inter-ventricular septum shift towards the LV and decreased LV diastolic volume. Right ventricular contractile dysfunction and acute tricuspid regurgitation cause decreased output from the RV, contributing to underfilling of the LV, with decreased cardiac output, decreased systemic blood pressure and decreased coronary perfusion, which may eventually cause circulatory collapse [19,20]. At present, the evaluation of patients with suspected PE consists of echocardiography and CTPA [3]. Echocardiography is both a rapid and accurate risk-assessment tool that is useful in identifying the PE patients who have a poor prognosis [3,21,22]. Its ability to visualize pulmonary arterial clots that are not very large or centrally located is, however, quite limited [21]. Its diagnostic ability is also operator and patient dependent [3]. Previous echocardiographic studies in PE patients mostly concentrated on the right and left ventricular measurements [21,23,24]. We are aware of only one echocardiography work that demonstrated that an increased ratio of right to left atrial end-systolic area correlated with obstruction of more than 30% of the pulmonary arterial tree [25]. This analysis, however, was conducted on 63 elderly patients and used ventilation/perfusion pulmonary scintigraphy to estimate the PE size: only 11 patients (17%) were found to have obstruction of > 30%. Nevertheless, the findings of that earlier study support those of our current work, in which we used CTPA in a larger and unselected group of PE patients and controls.

A number of CTPA studies have reported the presence of RV dilatation and an inter-ventricular septal shift towards the LV in association with severe PE [4–8]. The reduction of LA size, as seen on CPTA, in conjunction with a massive PE that is possibly due to reduced venous return as a result of the high clot load was, however, reported only in case reports [14,26]. Our current study is the first to show an association between the embolic extent, as expressed by PAOI, and atrial size. Because all the LA measurements were smallest for the group of patients with the highest pulmonary arterial obstruction, and gradually increased with smaller obstructions (the largest LA values were in the control group), increased mechanical obstruction can be considered to result in the reduction of pulmonary venous return to the LA. The respective increase in RA dimensions supports the presence of an additional mechanism (i.e. the so-called interdependence of the right and left cardiac chambers). Accordingly, under pericardial constriction, RV dysfunction causes not only impaired LV diastolic filling, but also enlargement of the RA due to increased RV-RA filling pressures, which leads to the compression and reduction in size of the adjacent LA [25]. Because both atrial walls are thin, while the LV wall is significantly thicker than the RV wall, the effect of this mechanism might be more pronounced between the atria.

Several authors found PAOI to predict mortality in acute PE [5,8,10,13], while others found no similar association between the two [4,6,9,15,27]. These contradictory findings might support the hypothesis that PE outcome is related to both embolus size and the underlying cardiopulmonary reserve [18,20]. Large-scale outcome studies are probably still required in order to clarify this issue.

The performance of cardiac-gated CT angiography for quantitative chamber assessment was recently compared with echocardiography, using oblique multi-planar reformations similar to those obtained by transthoracic echocardiography, and there was a good agreement score [17]. LA size assessment was based on its posterior-anterior diameter as seen on an oblique view alone, which we felt to be an inaccurate measure of its entire volume. We preferred to obtain a planimetric assessment, which we later used for RA measurement as well, because there is no previously published quantitative assessment of the RA on CT. Interestingly, it was recently shown that the LA diameter increases significantly with age, by up to 61% between the ages of 40 and 80 years [16]. Our results support this finding and also demonstrate gender differences in atrial parameters. Consequently, both atria measurements were adjusted to patients’ age and gender during the compilation of our results. Finally, RA dilatation in association with RV enlargement and hypokinesis in patients with PE had been previously reported on echocardiography [21], but not on CTPA.

One of our study’s limitations is its use of non-gated CT angiography for LA and RA measurements. Lu et al. [28] recently compared LV and RV measurements obtained from gated and non-gated CTPA in a cohort of 30 patients with acute PE. They found a high correspondence rate between measurements performed according to both protocols, and concluded that quantitative RV evaluation using gated CT in acute PE patients is not justified in the clinical setting. Our purpose was to examine data obtained from routine clinical settings. This was also the reason for obtaining atrial measurements directly from axial slices that are regularly used for PE assessment. Planimetric assessments rather than volumetric measurements comprise another drawback of this preliminary study: automated dedicated software for volumetric assessment of all cardiac chambers should be used in future studies after they are proven to be adequately accurate. Another limitation is the inability to provide sufficient data on the relationship between our findings and the patients’ outcomes, because most causes of death were not associated with the presence of PE alone. Finally, the lack of data on cardiac comorbidities, which may influence atrial dimensions as well as comparison in real time with echocardiography, which could provide functional correlation, are additional drawbacks that are also related to the retrospective nature of the study.

In conclusion, assessment of the association between the degree of embolic obstruction and the LA and RA areas revealed that a higher pulmonary arterial clot load is associated with a smaller LA area and a larger RA area. Our findings suggest that atrial dimensions as seen on CTPA may serve as an additional early parameter that reflects modifications in cardiac morphology in response to the extent of pulmonary arterial obstruction, and thus may contribute to a more comprehensive risk assessment in patients with acute PE.

Disclosure of Conflict of Interests

  1. Top of page
  2. Summary.
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Disclosure of Conflict of Interests
  8. References

The authors state that they have no conflict of interest.

References

  1. Top of page
  2. Summary.
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Disclosure of Conflict of Interests
  8. References
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