Prognostic value of coronary flow reserve and coronary calcification in patients with suspected coronary artery disease

Current cardiac PET and computed tomography imaging allows the simultaneous acquisition of anatomic and physiological data for patients suspected of CAD.

We aimed to evaluate the incremental prognostic value of coronary artery calcium (CAC) score and coronary flow reserve (CFR) in patients with suspected coronary artery disease (CAD) undergoing positron emission tomography (PET) myocardial perfusion imaging (MPI).

We included consecutive patients who underwent PET MPI and CAC score calculation at Houston Methodist Hospital between August 2019 and January 2022. MPI and CAC scores were obtained in the same setting. The primary endpoint of the study was MACE. Cox proportional hazard regression was used to assess the incremental prognostic value of CAC and CFR by sequentially adding the variables to a model that included clinical and PET variables.

A total of 2,072 patients (mean age 65.7±11.6 years, 54.7% women) were included in the analysis. Risk factors were prevalent (86.1% hypertension, 75.2% dyslipidemia, 45.5% diabetes). In total, 25.3% of the cohort had a CAC score of 0, 38.1% had CAC ≥400, and 39.9% had CFR <2. Over a median follow up of 6.26 (IQR 1.7–12.4) months, 66 (3.2%) patients had cardiac death/nonfatal myocardial infarction. CFR score added incremental prognostic value over clinical and perfusion variables alone (base model: c-index 0.75; Akaike information criterion [AIC]: 1,860.6; p<0.001; CFR model: c-index 0.78; AIC: 1,842.4; p=0.041). However, CAC score did not show an increased prognostic utility (CAC model: c-index 0.76; AIC: 1,854.8; p=0.087 vs. base model), and neither did the combined model of CAC and CFR scores (c-index 0.79; AIC: 1,839.4; p=0.366 vs. CFR model).

Among patients referred for PET MPI, CFR score added an increased prognostic value over clinical and MPI variables. However, when evaluating the prognostic utility of CAC alone, or of CAC and CFR combined, the multivariable model did not show any increased prognostic potential.

Type of funding sources: None.