Prognostic implications of myocardial perfusion defects: establishing cutoff values through dynamic computed tomography in patients with known or suspected coronary artery disease
Authors: Gonzalez Freixa C , Altadill Balsells F , Bos Real L , Salido Iniesta M , Fernandez Martinez J , Menduina Gallego I , Li C H , Pujadas Olano S , Descalzo Buey M , Leta Petracca R , Vilades Medel D 
Published: June 2024

Abstract

Introduction
Dynamic computed tomography perfusion (DynCTP) provides complementary functional information to anatomical studies, allowing the integration of the diagnostic process of coronary artery disease (CAD) into a single non-invasive imaging technique. However, there is currently insufficient evidence regarding the establishment of standardized cut-off values to determine the severity of detected perfusion defects and their potential prognostic impact.

Purpose
To establish cut-off values for assessing the severity of perfusion defects identified through DynCTP in symptomatic patients with suspected CAD or a history of chronic coronary syndrome (CCS).

Methods
We conducted a prospective, single-center observational study including unselected patients undergoing cardiac computed tomography angiography (CTCA) between April 2021 and April 2023. DynCTP was performed if a CAD-RADS score ≥3 or nonconclusive coronary segments were identified. A myocardial blood flow value ≤85 mL/100 mL of tissue per minute was employed to define myocardial segments with a positive perfusion defect. The extent of this anomaly was then expressed as the percentage of affected myocardial segments out of a total of 16. Three categories were established based on the perfusion defect extension: no defect (0 segments; 0% extension), mild-moderate defect (1-4 segments; 1-25% extension), and significant defect (5 or more segments; &gt;25% extension). The prognostic capacity was assessed using a composite of major cardiovascular events: cardiovascular mortality, acute coronary syndrome, and the necessity for revascularization.

Results
102 patients were included with a mean follow-up of 22 ± 7 months. DynCTP was performed on 56 (55%) subjects, yielding positive results in 43 (77%) of them. DynCTP patients were predominantly male (77%) with a mean age of 72 years. The prevalence of cardiovascular risk factors was high: 80% had hypertension and dyslipidemia, 27% had diabetes, and 39% were smokers. 50% had a prior history of CCS, whereas the pretest risk of CAD in patients without known CCS was 35 ± 11%. In the pre-DynCTP CTPA, CAD-RADS score averaged 3.9 ± 1, with a mean Segment Involvement Score (SIS) of 8.4 ± 2.9 and a mean Segment Stenosis Score (SSS) of 9 ± 5.6. The presence of a significant perfusion defect was associated with a higher incidence of cardiac catheterizations and major cardiovascular events (Table 1). Graph 1 depicts the analysis of cardiovascular event-free survival over time in relation to the proposed cutoff values, showing significant differences between groups.

Conclusion
In our cohort, the identification of a significant perfusion defect in DynCTP, defined as the presence of 5 or more affected segments (&gt;25% extension), was associated with a significantly higher incidence of major cardiovascular events. All patients in this group who underwent invasive coronary angiography were subsequently subjected to coronary revascularization.Table 1 Graph 1