Dobutamine stress echocardiography after positive CCTA: diagnostic performance using fractional flow reserve and instantaneous wave-free ratio as reference standards

Abstract

Aims: To assess the diagnostic accuracy of dobutamine stress echocardiography (DSE) in symptomatic patients with a low to intermediate pretest probability of obstructive coronary artery disease (CAD) and a positive coronary CT angiography (CCTA).

Methods: We prospectively enrolled 104 consecutive patients undergoing coronary angiography for symptoms of stable CAD and a CCTA indicative of obstructive CAD. The diagnostic performance of DSE was evaluated against two intracoronary pressure indices: (a) fractional flow reserve (FFR) with a cut-off of ≤0.80 and (b) instantaneous wave-free ratio (iFR) with a cut-off of ≤0.89, indicating haemodynamically significant stenoses.

Results: Of 102 patients, 46 (45%) had at least one significant lesion as defined by FFR, as did 37 (36%) as defined by iFR. DSE showed positive results in 33% (34/102) of cases. The discriminative power of DSE for detecting significant CAD was moderate, with areas under the curve of 0.63 (p=0.024) compared with FFR and 0.64 (p=0.025) compared with iFR. The accuracy, sensitivity and specificity of DSE were, respectively, 61%, 43%, and 75% against FFR, and 64%, 46% and 74% against iFR. The diagnostic accuracy of DSE did not differ significantly between FFR and iFR as a reference (p=0.549).

Conclusion: In patients with positive CCTA, DSE has a moderate ability to identify haemodynamically significant CAD, with low sensitivity and moderate specificity. When assessed against FFR and iFR criteria, its additive diagnostic value is limited in patients with low to intermediate pretest probability of obstructive CAD.

Trial registration number: NCT03045601.

Keywords: Angina Pectoris; CORONARY ARTERY DISEASE; Computed Tomography Angiography; Echocardiography; FRACTIONAL FLOW RESERVE.

Figure 1. Case example. A patient with an intermediate pretest probability of obstructive CAD; hypertension, typical angina and exertional dyspnoea over the last year; and CCTA showing a significant stenosis in the proximal left anterior descending artery (A, green arrow). ICA confirmed an intermediate stenosis (B, orange arrow). FFR was 0.66 and iFR 0.85 (C, blue arrow), both of functional significance (C, E, F). DSE showed a biphasic response to dobutamine with improved contractile response at low dose and worsening wall motion abnormalities in the septal and anteroseptal wall during peak dobutamine infusion (D, red arrow). CAD, coronary artery disease; CCTA, coronary CT angiography; DSE, dobutamine stress echocardiography; FFR, fractional flow reserve; ICA, invasive coronary angiography; iFR, instantaneous wave-free ratio.

Figure 2. Distribution of (A) FFR and (B) IFR measurements. Outliers are indicated in red, defined as values below the lower quartile minus three times the IQR. FFR, fractional flow reserve; IFR, instantaneous wave-free ratio.

Figure 3. ROC curve analysis for stress echocardiography to detect haemodynamically significant CAD as defined by (A) FFR ≤0.80 and (B) iFR ≤0.89. ∆ WMSI represents the change in WMSI from baseline to peak stress. AUC, area under the curve; CAD, coronary artery disease; FFR, fractional flow reserve; iFR, instantaneous wave-free ratio; ROC, receiver operating characteristic; WMSI, Wall Motion Score Index.

Figure 4. Diagnostic performance of stress echocardiography for detecting hemodynamically significant CAD as defined by FFR ≤0.80 and IFR ≤0.89. Results are presented with 95% CLs. FFR, fractional flow reserve; iFR, instantaneous wave-free ratio.