Thrombus Burden After Thrombectomy or PCI-Alone in STEMI
Thrombus Burden After Thrombectomy or PCI-Alone in STEMI
Of the 214 patients in the OCT sub-study, 104 were randomized to thrombectomy and 110 to PCI-alone (Figure 2). One patient in the thrombectomy group crossed over to PCI-alone and five patients in the PCI-alone group had bailout thrombectomy after a failure of the initial PCI-alone strategy. Interpre pre-stent images were obtained in 85 of 104 in the thrombectomy arm and 88 of 110 patients in the PCI-alone arm. Interpretable post-stent images were obtained in 84 of 104 patients in the thrombectomy arm and 89 of 110 patients in the PCI-alone arm. Reasons for not performing OCT imaging or for lack of interpretability of the acquired images are shown in Figure 2.
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Figure 2.
Patient flow diagram. Asterisk indicates TIMI 2/3 flow achieved, but vessel reoccluded by imaging catheter.
Baseline characteristics of the patients were well balanced ( Table 1 ). The PCI procedure details and angiographic results are shown in Table 2 . TIMI thrombus burden 5 was present in 54.5% of thrombectomy patients and 61.1% of PCI-alone patients. Direct stenting was performed more frequently in the thrombectomy group (36.5 vs. 10.9%, P<0.0001). Glycoprotein IIb/IIIa inhibitor use was not different between the groups. Post PCI, TIMI 2 or 3 flow was obtained in all but one patient in each group. Rates of angiographic no reflow and distal embolization were low and not different between the groups.
The primary outcome of pre-stent thrombus burden as a percentage of the analysed segment was 2.36% (95% CI 1.73–3.22) in the thrombectomy group and 2.88% (95% CI 2.12–3.90) in the PCI-alone group (P = 0.373) ( Table 3 ). Scatter plots of pre-stent thrombus burden by the treatment group are shown in Figure 3. There was no difference in percent pre-stent thrombus burden in subgroups of TIMI thrombus grade <4 vs. ≥4 or TIMI thrombus grade <3 vs. ≥3 ( Table 4 ). Absolute pre-stent thrombus volume was not different (2.99 vs. 3.74 mm, P = 0.329) between thrombectomy and PCI-alone. Scatter plots of absolute pre-stent thrombus volume by treatment group are shown in Figure 4. Additional absolute (quadrants of thrombus, maximal thrombus area) and relative (quadrants of thrombus/mm) measures of pre-stent thrombus showed no difference between groups ( Table 3 ). Post hoc subgroup analysis comparing baseline TIMI flow 0 or 1 vs. 2 or 3 did not show any difference in pre-stent thrombus burden (see Supplementary material online, Table S1). The semi-quantitative measure pre-stent quadrants of thrombus was highly correlated with our primary outcome pre-stent thrombus burden (r = 0.91) (see Supplementary material online, Figure S1).
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Figure 3.
Scatter plot of pre-stent thrombus burden by treatment group.
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Figure 4.
Scatter plot of pre-stent thrombus volume by treatment group.
Post-stent atherothrombotic burden was 6.23% (95% CI 5.74–6.76) in the thrombectomy group and 5.71% (95% CI 5.27–6.18) in the PCI-alone group (P = 0.136). There was no difference in post-stent atherothrombotic burden in subgroups of TIMI thrombus grade <4 vs. ≥4 or TIMI thrombus grade <3 vs. ≥3 ( Table 4 ). Absolute measures of post-stent thrombus burden (atherothrombotic volume and maximal atherothrombotic area) also did not show any difference between the groups ( Table 3 ). Post hoc sub-group analysis comparing baseline TIMI flow 0 or 1 vs. 2 or 3 did not show any difference in post-stent atherothrombotic burden (see Supplementary material online, Table S1). There was low correlation between post-stent atherothrombotic burden and pre-stent thrombus burden (r = 0.34) overall and by the treatment group (thrombectomy r = 0.29, PCI-alone 0.38) (Figure 5).
(Enlarge Image)
Figure 5.
Correlation between pre-stent thrombus burden and post-stent atherothrombotic burden.
Results
Of the 214 patients in the OCT sub-study, 104 were randomized to thrombectomy and 110 to PCI-alone (Figure 2). One patient in the thrombectomy group crossed over to PCI-alone and five patients in the PCI-alone group had bailout thrombectomy after a failure of the initial PCI-alone strategy. Interpre pre-stent images were obtained in 85 of 104 in the thrombectomy arm and 88 of 110 patients in the PCI-alone arm. Interpretable post-stent images were obtained in 84 of 104 patients in the thrombectomy arm and 89 of 110 patients in the PCI-alone arm. Reasons for not performing OCT imaging or for lack of interpretability of the acquired images are shown in Figure 2.
(Enlarge Image)
Figure 2.
Patient flow diagram. Asterisk indicates TIMI 2/3 flow achieved, but vessel reoccluded by imaging catheter.
Baseline characteristics of the patients were well balanced ( Table 1 ). The PCI procedure details and angiographic results are shown in Table 2 . TIMI thrombus burden 5 was present in 54.5% of thrombectomy patients and 61.1% of PCI-alone patients. Direct stenting was performed more frequently in the thrombectomy group (36.5 vs. 10.9%, P<0.0001). Glycoprotein IIb/IIIa inhibitor use was not different between the groups. Post PCI, TIMI 2 or 3 flow was obtained in all but one patient in each group. Rates of angiographic no reflow and distal embolization were low and not different between the groups.
The primary outcome of pre-stent thrombus burden as a percentage of the analysed segment was 2.36% (95% CI 1.73–3.22) in the thrombectomy group and 2.88% (95% CI 2.12–3.90) in the PCI-alone group (P = 0.373) ( Table 3 ). Scatter plots of pre-stent thrombus burden by the treatment group are shown in Figure 3. There was no difference in percent pre-stent thrombus burden in subgroups of TIMI thrombus grade <4 vs. ≥4 or TIMI thrombus grade <3 vs. ≥3 ( Table 4 ). Absolute pre-stent thrombus volume was not different (2.99 vs. 3.74 mm, P = 0.329) between thrombectomy and PCI-alone. Scatter plots of absolute pre-stent thrombus volume by treatment group are shown in Figure 4. Additional absolute (quadrants of thrombus, maximal thrombus area) and relative (quadrants of thrombus/mm) measures of pre-stent thrombus showed no difference between groups ( Table 3 ). Post hoc subgroup analysis comparing baseline TIMI flow 0 or 1 vs. 2 or 3 did not show any difference in pre-stent thrombus burden (see Supplementary material online, Table S1). The semi-quantitative measure pre-stent quadrants of thrombus was highly correlated with our primary outcome pre-stent thrombus burden (r = 0.91) (see Supplementary material online, Figure S1).
(Enlarge Image)
Figure 3.
Scatter plot of pre-stent thrombus burden by treatment group.
(Enlarge Image)
Figure 4.
Scatter plot of pre-stent thrombus volume by treatment group.
Post-stent atherothrombotic burden was 6.23% (95% CI 5.74–6.76) in the thrombectomy group and 5.71% (95% CI 5.27–6.18) in the PCI-alone group (P = 0.136). There was no difference in post-stent atherothrombotic burden in subgroups of TIMI thrombus grade <4 vs. ≥4 or TIMI thrombus grade <3 vs. ≥3 ( Table 4 ). Absolute measures of post-stent thrombus burden (atherothrombotic volume and maximal atherothrombotic area) also did not show any difference between the groups ( Table 3 ). Post hoc sub-group analysis comparing baseline TIMI flow 0 or 1 vs. 2 or 3 did not show any difference in post-stent atherothrombotic burden (see Supplementary material online, Table S1). There was low correlation between post-stent atherothrombotic burden and pre-stent thrombus burden (r = 0.34) overall and by the treatment group (thrombectomy r = 0.29, PCI-alone 0.38) (Figure 5).
(Enlarge Image)
Figure 5.
Correlation between pre-stent thrombus burden and post-stent atherothrombotic burden.
