Application of the DILEMMA score to improve lesion selection for invasive physiological assessment

Abstract

Objectives: We sought to assess the validity of the DILEMMA score against instantaneous wave-free ratio (iFR) and evaluate its utility in rationalizing the number of patients referred for invasive physiological assessment.

Background: The DILEMMA score is a validated angiographic scoring tool incorporating minimal lumen diameter, lesion length and subtended myocardial area that has been shown to predict the functional significance of lesions as assessed by fractional flow reserve (FFR).

Methods: Patients in the DEFINE-FLAIR study who had coronary stenosis of intermediate severity were randomized to either FFR or iFR. DILEMMA score was calculated retrospectively on a subset of this cohort by operators blinded to FFR or iFR values.

Results: Three hundred and forty-six lesions (181 assessed by FFR; 165 by iFR) from 259 patients (mean age 66.0 years, 79% male) were included. A DILEMMA score ≤ 2 had a negative predictive value of 96.3% and 95.7% for identifying lesions with FFR >0.80 and iFR >0.89, respectively. A DILEMMA score ≥ 9 had a positive predictive value of 88.9% and 100% for identifying lesions with FFR ≤0.80 and iFR ≤0.89, respectively. The receiver operating characteristic area under the curve values for DILEMMA score to predict FFR ≤0.80 and iFR ≤0.89 were 0.83 (95% CI 0.77-0.90) and 0.82 (0.75-0.89) respectively. A DILEMMA score ≤ 2 or ≥9 occurred in 172 of the 346 lesions (49.7%).

Conclusions: Using DILEMMA score in patients with coronary stenosis of intermediate severity may reduce the need for pressure wire use, offering potential cost-savings and minimizing the risks associated with invasive physiological lesion assessment.

Keywords: angiography, coronary; coronary artery disease; coronary blood flow/physiology/microvascular function; fractional flow reserve; percutaneous coronary intervention.

Figure 1

Scatter plot of 181 lesions that underwent FFR assessment and corresponding DILEMMA scores. Of the total, 90 lesions (49.7%) had a DILEMMA score ≤ 2 or ≥9 (green boxes)

Figure 2

Scatter plot of 165 lesions that underwent iFR assessment and corresponding DILEMMA scores. Of the total, 82 lesions (49.7%) had a DILEMMA score ≤ 2 or ≥ 9

Figure 3

Receiver operating characteristic curve for DILEMMA score, MLD, LL and BARI MJI to predict (A) FFR ≤0.80 (ROC AUC values 0.83, 0.77, 0.80 and 0.62, respectively) and (B) iFR ≤0.89 (ROC AUC values 0.82, 0.74, 0.75 and 0.73, respectively)

Figure 4

Example lesions assessed by DILEMMA score with breakdown of minimal lumen diameter (MLD), lesion length (LL) and Bypass Angioplasty Revascularization Investigation Myocardial Jeopardy Index (BARI MJI). Panel A demonstrates a lesion causing luminal stenosis in the proximal LAD with MLD of 0.73 mm and LL of 6.55 mm. BARI MJI was calculated by dividing the sum of the vessels subtending the lesion (in this case, 5) by the sum of all the vessels supplying the left ventricle (in this case, 16) giving 38%. The calculated DILEMMA score is therefore 9. Panel B presents the corresponding iFR of 0.80. Panel C demonstrates a lesion causing luminal stenosis in the distal RCA with MLD of 2.29 mm and LL of 11.69 mm. BARI MJI was calculated by dividing 7 (for the sum of the vessels subtending the RCA lesion) by 21 (for the sum of all the vessels supplying the left ventricle), giving 33%. The calculated DILEMMA score is therefore 2. Panel D presents the corresponding FFR of 0.88