SPECT V/Q yielded a low 0.5% 3-month VTE risk in untreated patients, but early trial termination prevented formal demonstration of non-inferiority against standard pulmonary embolism imaging.
Does a SPECT V/Q-based diagnostic strategy safely rule out PE (measured by 3-month VTE risk in untreated patients) compared to CTPA and planar V/Q in patients with suspected pulmonary embolism?
Although the trial was terminated early and failed to formally demonstrate non-inferiority, a SPECT V/Q-based diagnostic strategy for suspected PE resulted in a low 3-month VTE risk (0.5%) following a negative work-up.
Absolute Event Rate: 0% vs 0%
Introduction While single-photon emission computed tomography (SPECT) V/Q has been widely adopted for pulmonary embolism (PE) diagnosis, it is not currently endorsed by clinical guidelines due to insufficient evidence. Methods We conducted a non-inferiority randomised trial comparing SPECT V/Q, computed tomography pulmonary angiography (CTPA), and planar V/Q-based diagnostic strategies using a 2:1:1 allocation. The primary endpoint was the 3-month risk of venous thromboembolism (VTE) in untreated patients with a negative work-up, comparing SPECT V/Q to the combined CTPA and planar V/Q arms. A non-inferiority margin of 1% absolute difference in 3-month VTE risk was defined. Secondary outcomes included PE diagnosis rates. The trial ended prematurely in October 2024 due to slow recruitment and funding limitations. Results From July 2017 to October 2024, 603 patients were randomised. PE was diagnosed in 61/303 (20.1%) in the SPECT V/Q arm, 31/150 (20.7%) in the CTPA arm, and 24/150 (16.0%) in the planar V/Q arm. The 3-month VTE risk in patients left untreated after a negative work-up was 0.5% (1/221) for SPECT V/Q, 0.0% (0/107) for CTPA, and 0.8% (1/118) for planar V/Q. The difference in outcome between SPECT V/Q and the combined arms was 0.0% (95%CI −1.2% to 1.3%; p for non-inferiority=0.75). Conclusion After being prematurely discontinued, this randomised trial did not demonstrate the non-inferiority of a SPECT V/Q-based strategy to reference standards for PE diagnosis. However, the results suggest a low 3-month VTE risk in patients managed using a SPECT V/Q-based diagnostic strategy. Among patients with clinically suspected acute PE requiring chest imaging, a SPECT V/Q-based algorithm might be a reliable alternative in clinical practice.
Pennec et al. (Thu,) reported a other. SPECT V/Q yielded a low 0.5% 3-month VTE risk in untreated patients, but early trial termination prevented formal demonstration of non-inferiority against standard pulmonary embolism imaging.