SPC365

ISCHEMIA LBBB Study - Is an anatomical approach superior to a functional approach for the diagnosis of obstructive coronary artery disease in patients with left bundle branch block?

Session: CO 01 - Doença coronária
Speaker: Pedro Teixeira Carvalho

Congress: CPC 2021
Topic: E. Coronary Artery Disease, Acute Coronary Syndromes, Acute Cardiac Care
Theme: 12. Coronary Artery Disease (Chronic)
Subtheme: 12.3 Coronary Artery Disease – Diagnostic Methods
Session Type: Comunicações Orais
FP Number: ---
Authors: Pedro Teixeira Carvalho; Adriana Pacheco; Diana Carvalho; Lisa Ferraz; Jose Luis Martins; Manuela Vieira; Nuno Ferreira; Ana Briosa Neves

<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri"><span style="color:#000000"><strong><span style="font-size:11pt"><span style="color:black">Background</span></span></strong></span></span></span></p>

<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri"><span style="color:#000000"><span style="font-size:11pt"><span style="color:black">The diagnostic investigation of obstructive coronary artery disease (CAD) in the presence of left bundle branch block (LBBB) or ventricular pacing (VP) is challenging because the inherent changes in ventricular depolarization may cause wall motion abnormalities or septal perfusion defects. These have been described as causes for false positive ischemia tests.&nbsp;</span></span></span></span></span></p>

<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri"><span style="color:#000000"><span style="font-size:11pt"><span style="color:black">The authors hypothesised that an anatomic test - computerized tomography coronary angiogram (CTCA) - might be more suitable than functional tests - single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) and dobutamine stress echocardiography (DSE) - for the diagnosis of CAD in these patients.&nbsp;</span></span></span></span></span></p>

<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri"><span style="color:#000000"><strong><span style="font-size:11pt"><span style="color:black">Methods</span></span></strong></span></span></span></p>

<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri"><span style="color:#000000"><span style="font-size:11pt"><span style="color:black">This was an observational multicentre study including consecutive patients with LBBB or VP referred for SPECT-MPI, DSE and CTCA. An analysis of accuracy, false discovery rate (FDR) and ROC curve was performed, including patients referred to coronary angiography (CA) after these exams. Exclusion criteria were acute coronary syndrome or previous CAD with incomplete revascularization. To avoid referral bias, a second analysis was performed evaluating the normalcy rate (NR) in a sample of low-risk patients (pre-test probability &lt;10%). A modified NR was used due to the reduced referral of patients with a pre-test probability &lt;5%.</span></span></span></span></span></p>

<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri"><span style="color:#000000"><strong><span style="font-size:11pt"><span style="color:black">Results</span></span></strong></span></span></span></p>

<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri"><span style="color:#000000"><span style="font-size:11pt"><span style="color:black">Of the 346 patients included in the study, 132 were referred to CA - 77 after SPECT-CT, 28 after DSE and 27 after CCTA. The median age was 68 years (95%CI 60-75), 59% were male and 9% had undergone previous revascularization. CA revealed CAD in 32%, similar for all non-invasive exams (30%, 36% and 33% for SPECT-MPI, DSE and CTCA respectively,&nbsp;<em>p= .836</em>). Accuracy was significantly inferior for SPECT (34%) than DSE (68%, <em>p= .003</em>) or CTCA (63%, <em>p= .012</em>). FDR was significantly higher for SPECT-MPI (71%) than DSE (44%, <em>p= .049</em>) and similar to CTCA (53%, <em>p=.167</em>). There was no significant difference between CTCA and DSE (<em>p=.781</em>&nbsp;for accuracy, <em>p=.746</em>&nbsp;for FDR). The ROC curves revealed that SPECT-MPI was a poor discriminator of CAD in these patients (AUC 0.503, 95%CI 0.361-0.644). DSE (AUC 0.700, 95%CI 0.503-0.897) and CTCA (AUC 0.722, 95%CI 0.533-0.911) were decent discriminators.</span></span></span></span></span></p>

<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri"><span style="color:#000000"><span style="font-size:11pt"><span style="color:black">For the modified NR analysis, 214 low risk patients were included (93 for SPECT-CT, 40 for DSE and 81 for CCTA). Median age was 60 years (95%CI 54-64), 43% were male. The modified NR was significantly inferior for SPECT-MPI (27%) than DSE (83%,&nbsp;<em>p&lt;0.001</em>) or CTCA (85%,&nbsp;<em>p&lt;.001</em>), but not significantly different between DSE and CTCA (<em>p=.792</em>).</span></span></span></span></span></p>

<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri"><span style="color:#000000"><strong><span style="font-size:11pt"><span style="color:black">Conclusion</span></span></strong></span></span></span></p>

<p><span style="font-size:11pt"><span style="color:black"><span style="font-family:Calibri">In patients with LBBB or VP, SPECT-MPI performed poorly for the diagnosis of CAD, with a low accuracy, high FDR and a low modified NR. Despite the poor performance of SPECT-MPI, DSE and CTCA performed well, suggesting that an anatomical based approach is not superior to a functional based approach for the diagnosis of CAD in these patients.&nbsp;</span></span></span></p>