Summary
Background
Bifurcation lesions (BFLs) remain a challenging lesion subset, often associated with lower success rates than less complex lesions. There are few data regarding the impact of BFLs in the setting of ST-segment elevation myocardial infarction (STEMI).
Aims
To assess the impact of BFLs on angiographic characteristics and procedural success in primary percutaneous coronary interventions (PCIs).
Methods
Out of 1070 primary PCIs performed between November 2006 and December 2008, 114 patients (10.7%) with a BFL (side branch ≥ 2.0 mm) were identified and matched with 114 patients without a BFL, according to age, sex and infarct-related artery.
Results
Baseline characteristics were similar in both groups. Using the Medina classification, true BFLs ([1,1,1]; [1,0,1]; [0,1,1]) were found in 46.5% of cases. Mean contrast volume (265 ± 91 and 207 ± 68 mL), procedural time (51.0 ± 26.6 vs 35.3 ± 11.5 min) and fluoroscopy time (16.2 ± 11.2 vs 9.8 ± 5.1 min) were significantly higher in the BFL group than the non-BFL group ( p < 0.0001). However, time to reperfusion and angiographic success rates (residual stenosis ≤ 30% and Thrombolysis in Myocardial Infarction flow grade 3 in main branch) were similar in BFL and non-BFL patients (13.7 ± 7.9 vs 12.1 ± 5.7 min, respectively, p = 0.087; 96.5 vs 99.1%, respectively, p = 0.18), with no periprocedural events (in-hospital death, emergent coronary artery bypass graft or repeat PCI < 24 h).
Conclusion
Despite being challenging lesions, BFLs in STEMI were associated with similar time to reperfusion and procedural success but led to significantly greater contrast use and prolonged procedural time compared with non-BFLs.
Résumé
État des lieux
Le traitement des bifurcations reste un défi, avec un taux de succès souvent plus faible que pour des lésions moins complexes. Peu de données existent concernant l’impact des bifurcations lors d’infarctus du myocarde avec surélévation du segment ST.
Objectifs
Evaluer l’impact des bifurcations sur les caractéristiques angiographiques et le succès procédural dans l’angioplastie primaire.
Méthodes
Sur 1070 angioplasties primaires réalisées entre novembre 2006 et décembre 2008, 114 patients (10,7 %) avec une lésion de bifurcation (branche fille ≥ 2,0 mm) ont été identifiées et appariés avec 114 patients sans lésion de bifurcation, selon l’âge, le sexe et l’artère coupable.
Résultats
Les caractéristiques de base sont comparables entre les deux groupes. En utilisant la classification de Medina, les vraies bifurcations ([1,1,1] ; [1,0,1] ; [0,1,1]) ont été retrouvées dans 46,5% des cas. Le volume moyen de contraste (265 ± 91 mL et 207 ± 68 mL), les temps moyens de procédure et de fluoroscopie (51,0 ± 26,6 min vs 35,3 ± 11,5 min, et 16,2 ± 11,2 min versus 9,8 ± 5,1 min, respectivement) sont significativement plus élevés dans le groupe bifurcation que dans le groupe non-bifurcation ( p < 0,0001). Cependant, le temps de reperfusion (13,7 ± 7,9 min vs 12,1 ± 5,7 min, p = 0,086) et le taux de succès angiographique (sténose résiduelle ≤ 30% et TIMI 3 in MB) sont similaires dans les deux groupes ( p = 0,18).
Conclusion
Lors d’infarctus du myocarde avec surélévation du segment ST, les lésions de bifurcations sont associées à un temps de reperfusion et à un succès procédural similaires, mais nécessitent une quantité de contraste plus élevée et prolongent le temps de la procédure en comparaison avec des lésions de non bifurcation.
Abbreviations
BFL
bifurcation lesion
MB
main branch
PCI
percutaneous coronary intervention
SB
side branch
STEMI
ST-segment elevation myocardial infarction
TIMI
Thrombolysis in Myocardial Infarction
Background
Bifurcation lesions (BFLs) remain one of the most challenging lesion subsets in percutaneous coronary intervention (PCI) besides chronic total occlusions, and are often associated with lower success and higher complication rates relative to less complex lesions. Several percutaneous coronary techniques have been described for approaching BFLs. The provisional T-stenting, culotte and crush techniques are among the most frequently used and most experts agree on some procedural features that improve the outcome of bifurcation PCI .
Before the Medina classification was adopted by the European Bifurcation Club in 2006, several other classifications of varying complexity were available to describe BFLs but all required a significant memorization effort. The Medina classification is straightforward and does not need to be memorized, thus making the description of the anatomy of coronary bifurcations much simpler.
Although BFLs represent up to 23% of all coronary lesions treated by PCI , there are few data regarding the incidence, Medina classification data and outcome of BFLs in the setting of ST-segment elevation myocardial infarction (STEMI) . The aim of our study was to describe and analyse the impact of BFLs on angiographic characteristics and procedural success in primary PCI.
Methods
Study population
Examination of the local database at the Montreal Heart Institute allowed the identification of 1070 patients referred to our institution for primary PCI in the setting of a STEMI between 1 November 2006 and 31 December 2008. Out of these 1070 primary angioplasties, by reviewing all the coronary angiogram images and reports, we identified 114 patients with a de novo BFL involving a significant side branch (SB) in the infarct-related artery. Then, according to age, sex and infarct-related artery, we individually matched the BFL group with a group of 114 patients presenting with STEMI not involving a BFL. Demographic, angiographic and procedural characteristics of both groups were analyzed.
Definitions
STEMIs were diagnosed according to the American College of Cardiology/American Heart Association criteria . BFLs correspond to greater than 50% coronary artery narrowing occurring adjacent to and/or involving the origin of a significant SB .
The inclusion criteria in the BFL group were a de novo BFL with a significant SB, defined as a vessel with a reference diameter greater or equal to 2.0 mm by visual assessment, in patients presenting with STEMI and referred for primary PCI. Distal left main and bypass graft anastomotic lesions were excluded.
The Medina classification was used to categorize all BFLs ( Fig. 1 ). Two interventionists reviewed the first 60 BFL angiograms for inter- and intra-observer variability. The pattern of bifurcation disease was further classified into “true” BFLs, where both main branch (MB) and SB present greater than 50% diameter stenosis (Medina [1,1,1]; [1,0,1]; [0,1,1]) and “false” BFLs, where only the MB or SB is significantly narrowed (Medina [1,1,0]; [1,0,0]; [0,1,0]; [0,0,1]) .
Flow in the infarct-related vessel was graded according to the Thrombolysis in Myocardial Infarction (TIMI) trial classification . The thrombus burden was assessed according to the TIMI thrombus grade on a scale from 0 to 5 (0 = no cine-angiographic thrombus present; 1 = possible thrombus; 2 = definite thrombus, with largest dimensions ≤ 50% of the vessel diameter; 3 = thrombus > 50% but < 2× the vessel diameter; 4 = thrombus with the largest dimensions ≥ 2× the vessel diameter; 5 = occlusion of the vessel).
MB angiographic success was defined as residual stenosis less or equal to 30% and TIMI flow grade 3. SB angiographic success was defined as residual stenosis less or equal to 50% and TIMI flow grade 3. Residual stenosis was judged by visual assessment. Procedural success corresponded to angiographic success without death, emergency coronary artery bypass graft and/or repeat PCI during the first 24 hours.
Procedural characteristics
Primary PCIs were performed by 13 different experienced operators either by femoral or radial access. In our centre, the radial approach is encouraged in order to decrease bleeding complications, especially when treating STEMI . 6-French diagnostic and angioplasty materials were routinely selected according to the target vessel and lesion type and morphology. All patients were pre-medicated with aspirin 325 mg together with a 600 mg loading dose of clopidogrel and intravenous heparin. The activated clotting time was monitored throughout the intervention with a target of 250 s or longer. Glycoprotein IIb/IIIa inhibitors were routinely administered unless major bleeding risk was a concern. In the BFL group, the treatment strategy was determined according to the subtype of BFL but provisional T-stenting was the preferred technique in our institution. Pre-dilatation and final kissing balloon inflation were left to the operator’s discretion.
Statistical analysis
Continuous variables are expressed as mean values ± one standard deviation if normally distributed, and as median values with interquartile ranges if the distribution was skewed. Continuous variables were compared by the t test if normally distributed and by the Wilcoxon Mann-Whitney test if skewed. Categorical variables were compared using a chi-square test and expressed as numbers and percentages. P values smaller than 0.05 were considered statistically significant. All analyses were done with SAS (version 8.2; SAS Institute, Cary, NC, USA). The inter- and intra-observer variability in the Medina classification categorization is expressed as a percentage and kappa coefficient reflecting the rate of agreement between the two observers or the two assessments by the same observer at a 30-day interval. Agreement was considered to have been reached when there was a concordance for the three Medina classification components.
Results
Patient and lesion characteristics
Bifurcation as a culprit lesion in STEMI was detected in 114 out of 1070 patients (10.7%). The 114 patients with a non-bifurcation culprit lesion were well matched to the 114 BFL patients according to age (57.7 ± 11.0 years vs 57.7 ± 11.1 years, respectively), sex (80.7% men in both groups) and infarct-related artery (65% left anterior descending artery, 17.5% circumflex artery and 17.5% right coronary artery in both groups). Baseline characteristics were similar among the BFL and non-BFL groups, except for the presence of multivessel disease ( Table 1 ). Using the Medina classification, true BFLs ([1,1,1]; [1,0,1]; [0,1,1]) were found in 46.5% of cases ( n = 53/114) whereas false BFLs were noted in the remainder (53.5%, n = 61/114). The distribution of BFL subtypes according to the Medina classification is described in Table 2 .
| BFL group ( n = 114) | Non-BFL group ( n = 114) | p | |
|---|---|---|---|
| Mean age (years) | 57.7 ± 11.1 (32–87) | 57.7 ± 11.0 (34–89) | 0.995 |
| Men | 92 (80.7) | 92 (80.7) | 1.0 |
| Diabetes mellitus | 17 (14.9) | 11 (9.7) | 0.23 |
| Hypertension | 41 (36.0) | 39 (34.2) | 0.78 |
| Hypercholesterolaemia | 62 (54.4) | 58 (50.9) | 0.60 |
| Smoking history | 59 (51.8) | 63 (55.3) | 0.60 |
| Previous | 10 (8.8) | 16 (14.0) | 0.21 |
| Current | 49 (43.0) | 47 (41.2) | 0.79 |
| Obesity a | 29 (27.9) | 36 (33.0) | 0.42 |
| Previous MI | 1 (0.9) | 2 (1.8) | 0.56 |
| Previous PCI | 6 (5.3) | 2 (1.8) | 0.15 |
| CAD | 0.012 | ||
| One VD | 67 (58.8) | 88 (77.2) | |
| Two VD | 33 (29.0) | 18 (15.8) | |
| Three VD | 14 (12.3) | 8 (7.0) |
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