Mismatched and matched defects can be observed in preoperative and postoperative ventilation-perfusion (V/Q) scans of patients with chronic thromboembolic pulmonary hypertension (CTEPH), but the extent of the matched defects on preoperative scans show no significant associations with changes in clinical and hemodynamic parameters, according to findings from a retrospective study published in Clinical Imaging.

Researchers from the Cleveland Clinic used a local CTEPH registry to identify 27 patients with CTEPH who underwent pulmonary thromboendarterectomy surgery. These patients had both preoperative and postoperative V/Q scans (mean duration of postoperative V/Q scan, 90 days), which were graded for each lung segment as normal (number of segments=276), matched (n=34), or mismatched defect (n=176).

The investigators also collected information on preoperative and postoperative clinical and hemodynamic parameters, including New York Heart Association (NYHA) functional class, 6-minute walk distance (6MWD) in feet, N-terminal pro-brain natriuretic peptide (NT-proBNP), forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC), mean pulmonary arterial pressure (mPAP), cardiac output (CO), and cardiac index (CI), among others.

A total of 27 patients had 176 mismatched defects, and 111 of these defects (63%) improved following surgery. Approximately 65% of the 34 matched defects improved after surgery. The investigators observed 31 new mismatched defects after surgery.


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There were no significant associations between the number of preoperative matched defects and preoperative NYHA (95% CI, -0.57 to 0.16; P =.240), mPAP (95% CI, -0.59 to 0.14; P =.190), 6MWD (95% CI, -0.44 to 0.36; P =.834), NT-pro BNP (95% CI, -0.43 to 0.35; P =.823), FEV1/FVC (95% CI, -0.23 to 0.51; P =.403), CO (95% CI, -0.30 to 0.47; P =.632), or CI (95% CI, -0.37 to 0.40; P =.908).

There were also no significant associations between the number of improved matched defects and the change (presurgery to postsurgery) in NYHA (95% CI, -0.51 to 0.37; P =.691), mPAP (95% CI, -0.25 to 0.60; P =.354), 6MWD (95% CI, -0.40 to 0.50; P =.503), NT-proBNP (95% CI, -0.17 to 0.67; P =.196), CO (95% CI, -0.52 to 0.44; P =.836), CI (95% CI, -0.51 to 0.45; P =.869), right atrial pressure (95% CI, -0.16 to 0.71; P =.165), systolic pulmonary arterial pressure (95% CI, -0.23 to 0.67; P =.273), and diastolic pulmonary arterial pressure (95% CI, -0.46 to 0.50; P =.900).

Study limitations included the retrospective nature as well as the small sample size of the CTEPH patient population who had preoperative and postoperative V/Q scans available for analysis.

The researchers wrote that additional studies are needed “to conclusively assess whether the number and extent of matched defects on preoperative scans has adverse prognostic significance or not.”

Reference

Nachand D, Huang S, Bullen J, Heresi GA, Renapurkar RD. Assessment of ventilation-perfusion scans in patients with chronic thromboembolic pulmonary hypertension before and after surgery and correlation with clinical parameters [published online May 10, 2020]. Clin Imaging. doi:10.1016/j.clinimag.2020.04.041