Author + information
- Received January 4, 2017
- Revision received July 5, 2017
- Accepted July 7, 2017
- Published online October 1, 2018.
- Kenneth Chan, MBBSa,b,
- Stefanos Ioannidis, MBBSa,
- John G. Coghlan, MDa,
- Margaret Hall, MBChB, MSca and
- Benjamin E. Schreiber, MD, MAa,∗ ()
- aRoyal Free NHS Foundation Trust, London, United Kingdom
- bOxford Heart Centre, John Radcliffe Hospital, Oxford, United Kingdom
- ↵∗Address for correspondence:
Dr. Benjamin E. Schreiber, Royal Free NHS Foundation, Royal Free Hospital, Pond Street, London NW3 2QG, United Kingdom.
Objectives This study aimed to evaluate the incidence and clinical outcomes of abnormal ventilation/perfusion (V/Q) single-photon emission computed tomography (SPECT) without thromboembolism, especially in patients with group I pulmonary arterial hypertension (PAH).
Background American Heart Association/American College of Cardiology and European Society of Cardiology guidelines recommend V/Q scan for screening for chronic thromboembolic pulmonary hypertension. The significance of patients with abnormal V/Q SPECT findings but no thromboembolism demonstrated in further investigations remained unclear. A distinct pattern of global patchy changes not typical of thromboembolism is recognized, but guidelines for reporting these in the context of PAH are lacking.
Methods A total of 136 patients who underwent V/Q SPECT and right-sided heart catheterization showing mean pulmonary arterial pressure ≥25 mm Hg were included. V/Q SPECT findings were reported using European Association of Nuclear Medicine criteria for pulmonary embolism followed by computed tomography pulmonary angiography screening for positive thromboembolism and further invasive pulmonary angiography for distal thromboembolism. The abnormal V/Q SPECT images were further analyzed according to perfusion pattern into focal or global perfusion defects.
Results V/Q SPECT showed thromboembolic disease in 44 patients, but 19 of these patients had no thromboembolism demonstrated by pulmonary angiography. Among these patients, 15 of 19 (78.9%) had group I PAH, and the majority had diffuse, patchy perfusion defects. After redefining V/Q SPECT images according to the perfusion pattern, those patients with global perfusion defects had higher mean pulmonary arterial pressure compared with patients with focal perfusion defects and normal scans (mean difference +13.9 and +6.2 mm Hg, respectively; p = 0.0002), as well as higher pulmonary vascular resistance (mean difference +316.6 and +226.3 absolute resistance units, respectively; p = 0.004). Among patients with PAH, global perfusion defects were associated with higher all-cause mortality with a hazard ratio of 5.63 (95% confidence interval: 1.11 to 28.5) compared with patients with focal or no perfusion abnormalities.
Conclusions There is a high incidence of abnormal V/Q SPECT scans in nonthromboembolic PAH. Further studies are needed to investigate the poor outcome associated with abnormal V/Q SPECT findings in the context of PAH.
- chronic thromboembolic pulmonary hypertension
- pulmonary angiogram
- pulmonary arterial hypertension
- pulmonary hypertension
Dr. Hall is a former employee of GE Healthcare. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received January 4, 2017.
- Revision received July 5, 2017.
- Accepted July 7, 2017.
- 2018 American College of Cardiology Foundation
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