Literature Review 7 pages

aHeart of Internal Finland; c

Center, Tu August 17 2016.

See pa *Corre E-mail

0002-9149 http://dx.do

Usefulness of Post-coronary Dilation to Prevent Recurrent Myocardial Infarction in Patients Treated With

Percutaneous Coronary Intervention for Acute Coronary Syndrome (from the BASE ACS Trial)

Pasi P. Karjalainen, PhDa,*, Matti Niemelä, PhDb, Mika Laine, PhDc, Juhani K.E. Airaksinen, PhDd, Antti Ylitalo, PhDa, and Wail Nammas, PhDa

Stent underexpansion is associated with worse outcome after stent implantation. Whether

Center, Medic Helsink rku Un , 2016;

ge 349 spondin address

/16/$ - i.org/1

post-dilation (PD) improves outcome in patients with acute coronary syndrome (ACS) remains unclear. We performed post hoc analysis of outcome in patients from the BASE ACS (A prospective randomized comparison of titanium-nitride-oxide-coated bioactive stents with everolimus-eluting stents in acute coronary syndrome) trial who underwent PD versus those who did not. The BASE ACS trial randomized 827 patients (1:1) with ACS to receive either titanium-nitride-oxideecoated bioactive stents or everolimus-eluting stents. The primary end point was major adverse cardiac events (MACE): a composite of cardiac death, nonfatal myocardial infarction (MI), or ischemia-driven target lesion revasculari- zation. Follow-up was planned at 12 months and yearly thereafter for up to 7 years. Of 827 patients enrolled in the BASE ACS trial, 357 (43.2%) underwent PD. Median follow-up duration was 5 years. Patients who underwent PD had less frequent nonfatal MI events at long-term follow-up, compared with those who did not (4.5% vs 8.5%, respectively, p [ 0.02). The rates of MACE (15.7% vs 15.1%, respectively, p [ 0.81), and the other end- points, were not significantly different (p >0.5 for all). The results were consistent in pro- pensity scoreematched analysis (270 pairs). In patients treated with bioactive stents, those who underwent PD had a trend for a fewer nonfatal MI events (p [ 0.076). Comparably, in patients treated with everolimus-eluting stents, MACE and all the individual end points were comparable (p >0.5 for all). In conclusion, patients treated with early percutaneous coronary intervention for ACS who underwent PD had less frequent nonfatal MI events at long-term follow-up, compared with those who did not; MACE rates were not significantly different. � 2016 Elsevier Inc. All rights reserved. (Am J Cardiol 2017;119:345e350)

In the era of bare-metal stents, adjunctive post-dilation (PD) with noncompliant balloons inflated at higher pres- sure increased the final minimal stent area and doubled the frequency of optimal stent deployment.1 With modern stent delivery systems, optimal stent deployment improved from 35.6% to 56.5% after PD in unselected patients.2 Stent underexpansion independently predicted stent thrombosis (ST) after sirolimus-eluting stent implantation.3 Likewise, minimal stent area was smaller in patients with in-stent restenosis after sirolimus-eluting stent implantation for both de novo and restenotic lesions.4,5 Yet, the role of PD after implantation of new-generation drug-eluting stents in patients presenting with acute coronary syndrome (ACS) remains unclear. Several reports demonstrated safety of

Satakunta Central Hospital, Pori, Finland; bDepartment ine, Division of Cardiology, University of Oulu, Oulu, i University Hospital, Helsinki, Finland; and dHeart iversity Hospital, Turku, Finland. Manuscript received revised manuscript received and accepted September 29,

for disclosure information. g author: Tel: (þ358) 2-6277755; fax: (þ358) 2-6277757. : [email protected] (P.P. Karjalainen).

see front matter � 2016 Elsevier Inc. All rights reserved. 0.1016/j.amjcard.2016.09.057

titanium-nitride-oxideecoated bioactive stents (BAS) in unselected cohorts and in randomized trials of ACS.6e9 The BASE ACS (A prospective randomized comparison of ti- tanium-nitride-oxide-coated bioactive stents with ever- olimus-eluting stents in acute coronary syndrome) trial showed noninferiority of BAS versus everolimus-eluting stents (EES) for the primary end point of major adverse cardiac events (MACE) in patients with ACS, at long-term follow-up.9e12 In post hoc analysis of the trial, we explored the long-term clinical outcome of patients who underwent PD versus those who did not.

Methods

The trial design was previously described.9 In short, the BASE ACS trial was a prospective single-blinded random- ized trial conducted in 14 centers. From January 2009 to September 2010, we randomized 827 patients (1:1) present- ing with ACS who underwent early percutaneous coronary intervention to receive either BAS (Titan-2; Hexacath, Paris, France) or EES (Xience V; Abbott Vascular, Santa Clara, California). Follow-up was planned at 12 months and yearly thereafter through 7 years. The trial was initiated by the investigators and conducted according to the ethical

www.ajconline.org

Table 1 Baseline clinical, angiographic and procedural characteristics of the 2 study groups

Variable Post-Dilatation p Value

Yes (N ¼ 357) No (N ¼ 470) Age (years) 63.6 � 11.3 62.5 � 12.3 0.19 Women 86 (24.1%) 112 (23.8%) 0.93 Diabetes mellitus 64 (17.9%) 76 (16.2%) 0.50 Current smoker 116 (32.5%) 162 (34.5%) 0.55 Hyperlipidemia 195 (54.6%) 193 (41.1%) <0.001 Hypertension 176 (49.3%) 237 (50.4%) 0.74 Presentation by ST

elevation myocardial infarction

135 (37.8%) 186 (39.6%) 0.60

Stent used (BAS/EES) 49.6%/50.4% 51.1%/48.9% 0.67 Prior myocardial

infarction 39 (10.9%) 57 (12.1%) 0.59

Prior percutaneous coronary intervention

35 (9.8%) 48 (10.2%) 0.84

Prior coronary bypass 16 (4.5%) 21 (4.5%) 0.99 ACC/AHA Lesion

type B/C 320 (89.6%) 411 (87.4%) 0.33

Thrombus 154 (43.1%) 210 (44.7%) 0.65 Calcified lesions 178 (49.9%) 174 (37.0%) <0.001 Bifurcation lesions 84 (23.5%) 93 (19.8%) 0.19 Reference vessel diameter

(mm) 3.16 � 0.43 3.12 � 0.43 0.15

Lesion length (mm) 14.9 � 6.7 13.9 � 5.3 0.015 Stent diameter (mm) 3.18 � 0.44 3.12 � 0.44 0.08 Stent length (mm) 18.8 � 5.3 17.8 � 5.5 0.009 Total stent length per

lesion (mm) 21.9 � 8.9 19.8 � 8.7 0.001

Number of vessels treated per patient

1.15 � 0.39 1.14 � 0.39 0.84

Number of lesions treated per patient

1.20 � 0.52 1.18 � 0.49 0.59

Stents per culprit lesion 1.19 � 0.41 1.11 � 0.33 0.004 Direct stenting 85 (23.8%) 175 (37.2%) <0.001 Stent failure 2 (0.6%) 3 (0.6%) 1.00 Procedural success 355 (99.4%) 470 (100%) 0.18 Unfractionated heparin 78 (21.8%) 137 (29.1%) 0.018 Low-molecular weight

heparin 226 (63.3%) 257 (54.7%) 0.013

GP IIb IIIa inhibitor 99 (27.7%) 143 (30.4%) 0.39 Bivalirudin 45 (12.6%) 76 (16.2%) 0.15

Continuous variables are presented as mean � SD, whereas categorical variables are presented as frequency (percentage). ACC ¼ American College of Cardiology; AHA ¼ American Heart

Association; BAS ¼ bioactive stent; GP ¼ glycoprotein.

346 The American Journal of Cardiology (www.ajconline.org)

guidelines of the 1964 Declaration of Helsinki, as revised in 2013. Informed written consent was obtained from every patient after explanation of the trial protocol; the protocol was approved by the ethics committees of the coordinating center (Satakunta Central Hospital) and the other participating cen- ters. The trial is registered under ClinicalTrials.gov, with number NCT00819923.

Patientsnot previously maintained on aspirin werepretreated with aspirin at a loading dose of 250 mg orally or 250 to 500 mg intravenously and continued at a dose of 75 to 150 mg daily indefinitely. Oral clopidogrel was initiated at a loading dose of 300 to 600 mg before or immediately after the procedure and

continued at a dose of 75 mg daily. Patients in either group were prescribed clopidogrel for a minimum of 6 months and, there- after, for extended periods (maximum 12 months) at operator’s discretion. During the procedure, lowemolecular-weight or unfractionated heparin was administered intravenously in the standard dosage. Use of glycoprotein IIb and IIIa inhibitors or bivalirudin was left to operator’s discretion.

PD was performed using a noncompliant balloon slightly larger (0.25 to 0.5 mm) than the stent deployment balloon, inflated at higher pressures (�16 bars). The diagnostic criteria for noneST-segment elevation ACS and ST- segment elevation myocardial infarction (MI) were previ- ously described.9 The primary end point was the first occurrence of MACE: a composite of cardiac death, nonfatal MI, or ischemia-driven target lesion revascularization (TLR). Secondary end points included noncardiac death and definite ST. Cardiac death was defined as death from car- diovascular causes or any death without known cause. ST was adjudicated according to the criteria of definite ST described by the Academic Research Consortium.13 An in- dependent clinical events committee whose members were blinded to stent group allocation adjudicated all the indi- vidual end points according to the prespecified definitions.

Continuous variables were presented as mean � SD, whereas categorical variables were described with absolute and relative (percentage) frequencies. Comparisons between the 2 subgroups (patients who underwent PD vs those who did not) were performed using the unpaired t test for continuous variables and the Pearson chi-square test or Fisher’s exact test for categorical variables, as appropriate. Data analysis was based on the intention-to-treat principle. We observed significant differences between the 2 sub- groups in several baseline characteristics. Therefore, we performed a propensity scoreematched analysis of the 2 subgroups to estimate the impact of PD on the clinical outcome. We calculated the propensity score using a logistic regression model in which we included—as covariates—all the baseline clinical, angiographic, and procedural variables with a difference between the 2 subgroups as indicated by a p <0.1 in univariate analysis. The unmatched subgroup variable (PD vs non-PD) was entered in the model as the dependent variable. Probabilities predicted by the model were saved as a new variable: propensity score, which was then used to identify and select the matched pairs. Hosmer- Lemeshow test was used to assess the fit of the logistic regression model (chi-square: 12.18, p ¼ 0.143). Finally, we used the “Caliper and Radius” matching method for selec- tion of the matched pairs. Matching was performed based on an estimated caliper width of 0.2 the SD of the propensity score logit. Time-to-event curves were constructed using Kaplan-Meier estimates, based on all the available follow- up data for MACE, and were compared with the log-rank test. Comparison of the 2 subgroups (based on PD) for the clinical outcome was also performed stratified by stent group. All tests were 2 sided and statistical significance was set at 5%. Data were analyzed with SPSS, version 16.

Results

Of the 827 patients enrolled in the BASE ACS trial, 357 (43.2%) underwent PD. Median follow-up duration was

Table 2 Clinical outcome in the 2 study groups at long-term follow-up

Outcome Event Post-Dilatation Hazard Ratio (95% CI) p Value

Yes (N ¼ 357) No (N ¼ 470) MACE 56 (15.7%) 71 (15.1%) 1.05 (0.71 e 1.53) 0.81 Cardiac Death 15 (4.2%) 11 (2.3%) 1.83 (0.83 e 4.04) 0.12 Non-fatal MI 16 (4.5%) 40 (8.5%) 0.50 (0.28 e 0.92) 0.02 Ischemia-driven TLR 33 (9.2%) 36 (7.7%) 1.23 (0.75 e 2.01) 0.41 Non-cardiac Death 20 (5.6%) 17 (3.6%) 1.58 (0.82 e 3.07) 0.17 Definite ST 8 (2.2%) 10 (2.1%) 1.05 (0.41 e 2.69) 0.91

Variables are presented as frequency (percentage). CI ¼ confidence interval; MACE ¼ major adverse cardiac events; MI ¼ myocardial infarction; ST ¼ stent thrombosis.

15.7%

15.1%

Log rank, p=0.85

MACE (%)

Follow-up (years)

Post-dilata on

No Post-dilata on

30

20

10

0 0 1 2 3 4 5 6 7

Figure 1. Kaplan-Meier estimates of the primary end point (a composite of cardiac death, nonfatal myocardial infarction, or ischemia-driven TLR) in the 2 subgroups at long-term follow-up.

Coronary Artery Disease/Post-dilatation in Acute Coronary Syndrome 347

5.0 years; mean (SD) 4.2 years (1.9). Compared with those who did not, patients who underwent PD were more often dyslipidemic and had longer and more frequently calcified target lesions (p <0.05 for all). They underwent more often pre-dilation and received longer stents, with more stents per culprit lesion (p <0.05 for all). The other baseline clinical, angiographic, and procedural data were matched (Table 1).

Patients who underwent PD had less frequent nonfatal MI events at long-term follow-up, compared with those who did not (4.5% vs 8.5%, respectively, p ¼ 0.02). In patients who underwent PD, 16 patients developed nonfatal MI events: in 9 patients (56.3%), MI occurred while the patients were still on dual antiplatelet therapy; in these, 5 events (55.6%) occurred during the first 30 days. In patients who did not undergo PD, 40 patients developed nonfatal MI events: in 18 patients (45%), MI occurred while the patients

were still on dual antiplatelet therapy; in these, 12 events (66.7%) occurred during the first 30 days. The cumulative incidence of MACE was not significantly different between the 2 subgroups (15.7% vs 15.1%, respectively, p ¼ 0.81) (Table 2, Figure 1). The rates of cardiac death and ischemia- driven TLR were not significantly different (p >0.05 both). Definite ST and noncardiac death were not significantly different (p >0.05 both) (Table 2). Propensity score matching yielded 540 patients (270 pairs) with balanced baseline characteristics (Table 3). Consistently, in the pro- pensity scoreematched pairs, patients who underwent PD had less frequent nonfatal MI events, compared with those who did not (3.7% vs 10.0%, respectively, p ¼ 0.004). MACE and all the other individual end points were not significantly different between the 2 matched subgroups (p >0.05 for all) (Table 4). In patients treated with BAS, those who underwent PD had a trend for a fewer nonfatal MI

Table 3 Baseline clinical, angiographic and procedural characteristics of the 2 matched groups

Variable Post-Dilatation p Value

Yes (N ¼ 270) No (N ¼ 270) Age (years) 63.9 � 10.7 62.3 � 12.3 0.096 Women 68 (25.2%) 67 (24.8%) 0.93 Diabetes mellitus 53 (19.6%) 43 (15.9%) 0.26 Current smoker 88 (32.6%) 85 (31.5%) 0.78 Hyperlipidemia 139 (51.5%) 129 (47.8%) 0.38 Hypertension 142 (52.6%) 132 (48.9%) 0.38 Presentation by ST

elevation myocardial infarction

106 (39.3%) 96 (35.6%) 0.37

Stent used (BAS/EES) 52.2%/47.8% 53.7%/46.3% 0.73 Prior myocardial

infarction 33 (12.2%) 32 (11.9%) 0.89

Prior percutaneous coronary intervention

29 (10.7%) 32 (11.9%) 0.68

Prior coronary bypass 14 (5.2%) 12 (4.4%) 0.68 ACC/AHA Lesion

type B/C 239 (88.5%) 241 (89.3%) 0.78

Thrombus 118 (43.7%) 115 (42.6%) 0.79 Calcified lesions 124 (45.9%) 118 (43.7%) 0.60 Bifurcation lesions 61 (22.6%) 65 (24.1%) 0.68 Reference vessel

diameter (mm) 3.13 � 0.42 3.15 � 0.43 0.52

Lesion length (mm) 14.3 � 5.6 14.3 � 5.5 0.94 Stent diameter (mm) 3.15 � 0.44 3.16 � 0.45 0.90 Stent length (mm) 18.5 � 5.2 18.3 � 5.6 0.70 Total stent length per

lesion (mm) 21.1 � 8.9 21.1 � 9.4 0.91

Number of vessels treated per patient

1.13 � 0.36 1.14 � 0.39 0.73

Number of lesions treated per patient

1.17 � 0.44 1.18 � 0.50 0.85

Stents per culprit lesion 1.16 � 0.39 1.16 � 0.37 0.82 Direct stenting 79 (29.3%) 67 (24.8%) 0.24 Stent failure 1 (0.4%) 3 (1.1%) 0.62 Procedural success 269 (99.6%) 270 (100%) 1.00 Unfractionated heparin 68 (25.2%) 63 (23.3%) 0.61 Low-molecular weight

heparin 166 (61.5%) 175 (64.8%) 0.42

GP IIb IIIa inhibitor 72 (26.7%) 84 (31.1%) 0.25 Bivalirudin 34 (12.6%) 31 (11.5%) 0.69

Continuous variables are presented as mean � SD, whereas categorical variables are presented as frequency (percentage). ACC ¼ American College of Cardiology; AHA ¼ American Heart

Association; BAS ¼ bioactive stent; EES ¼ everolimus-eluting stent; GP ¼ glycoprotein.

348 The American Journal of Cardiology (www.ajconline.org)

events, compared with those who did not (2.8% vs 6.7%, respectively, p ¼ 0.076). MACE and the other end points were not significantly different (p >0.05 for all). Compa- rably, in patients treated with EES, MACE and all the in- dividual end points were not significantly different (p >0.5 for all).

Discussion

The current post hoc analysis of the BASE ACS trial demonstrated that patients treated with early percutaneous coronary intervention for ACS who underwent PD

following the index procedure had less frequent nonfatal MI events at long-term follow-up, compared with those who did not; such better outcome persisted after propensity scoree matched analysis. Moreover, the incidence of MI was slightly lower in patients who underwent PD after BAS implantation; yet, such incidence was comparable (between those who underwent PD and those who did not) after EES implantation. The current report is the first to address the impact of PD on the long-term clinical outcome after stent implantation in patients with ACS.

Drug-eluting stents effectively reduced restenosis rates and obviated the need for TLR in most patients who un- derwent percutaneous coronary intervention in contempo- rary clinical practice. Because PD was not routinely performed in trials that confirmed the efficacy of DES, the role of PD after drug-eluting stent implantation has ulti- mately come into question. In clinical practice, PD is usually operator decided and is rarely performed as a standard procedure. A few studies reported the angiographic and clinical outcome of high-pressure balloon PD after drug- eluting stent implantation. In an early study of unselected patients (n ¼ 6,479) who underwent drug-eluting stent im- plantation, operator-decided PD was associated with reduction of in-stent and in-segment late lumen loss and binary restenosis rates at 7-month follow-up; yet, the rates of overall and individual MACE (death, MI, and TLR) were similar; ST rates were similar.14 In a more recent study, unselected patients who underwent routine PD after drug-eluting stent implantation (n ¼ 279, nearly 55% first- generation drug-eluting stents) were compared with histor- ical controls who underwent ad hoc PD for suboptimal results (n ¼ 262, 32% PD). The former group demonstrated better immediate angiographic outcome versus the latter; at 12-month follow-up, routine PD was associated with lower rates of MACE (death, MI, target vessel revascularization, definite/probable ST), TLR, and target vessel revasculari- zation; however, MI included cases of periprocedural MI that were frequent in both groups (8.2% vs 8.4%, respec- tively).15 Another study explored the outcome of operator- decided PD in patients with ST-elevation MI (n ¼ 191) who underwent primary percutaneous coronary intervention with drug-eluting stents: compared with those who did not, patients who underwent PD had less often target vessel revascularization and definite/probable ST at 6-month follow-up; yet, the 2 groups had similar immediate angio- graphic outcome (Thrombolysis In Myocardial Infarction flow, myocardial blush).16 Nevertheless, no propensity score matching was performed in the aforementioned studies (2 of which are small sized); the comparison groups remained unmatched for several key baseline characteristics. More- over, outcome was reported at mid-term follow-up. Two other retrospective studies suggested worse outcome in pa- tients who underwent PD, versus those who did not. In post hoc analysis of the National Heart, Lung, and Blood Insti- tute Dynamic Registry, patients who presented with acute MI and underwent PD had a higher risk of death/MI at 1 year compared with non-PD, and repeat revascularization was similar; in those who presented without acute MI, outcome was similar.17 In large registry data, PD was associated with a higher restenosis risk, similar ST risk, but a lower death risk.18 In the current post hoc analysis of a

Table 4 Clinical outcome in the 2 matched groups at long-term follow-up

Outcome Event Post-Dilatation Hazard Ratio (95% CI) p Value

Yes (N ¼ 270) No (N ¼ 270) MACE 40 (14.8%) 44 (16.3%) 0.89 (0.56 e 1.42) 0.63 Cardiac Death 10 (3.7%) 7 (2.6%) 1.45 (0.54 e 3.85) 0.46 Non-fatal MI 10 (3.7%) 27 (10.0%) 0.35 (0.16 e 0.73) 0.004 Ischemia-driven TLR 24 (8.9%) 18 (6.7%) 1.37 (0.72 e 2.58) 0.33 Non-cardiac Death 16 (5.9%) 9 (3.3%) 1.83 (0.79 e 4.21) 0.15 Definite ST 6 (2.2%) 4 (1.5%) 1.51 (0.42 e 5.42) 0.52

Variables are presented as frequency (percentage). CI ¼ confidence interval; MACE ¼ major adverse cardiac events; MI ¼ myocardial infarction; ST ¼ stent thrombosis; TLR ¼ target lesion

revascularization.

Coronary Artery Disease/Post-dilatation in Acute Coronary Syndrome 349

randomized trial, patients who underwent PD had a lower incidence of nonfatal MI at long-term follow-up versus those who did not, both in crude and propensity scoree matched analysis. The incidence of definite ST was com- parable between the 2 groups, both in crude and matched analysis. Cases of probable ST (acute MI in the index vessel territory or cardiac death within 30 days of the index pro- cedure) could have contributed to the discrepancy between the relative rates of nonfatal MI and definite ST between the 2 comparison groups. Interestingly, the 6-month incidence of definite/probable ST was lower with PD in patients with ST-elevation MI who underwent primary percutaneous coronary intervention with drug-eluting stents.16

Stent underexpansion is common and portends a high risk of ST and restenosis after implantation of first- generation drug-eluting stents.3e5,19 Stent underexpansion is related to acute strut malapposition immediately after stent implantation.20 Stent segments with acute malap- position portend a higher risk of delayed neointimal strut coverage and late malapposition, compared with well- apposed segments at implantation.21 Moreover, thrombus resolution underneath the implanted stent might occur in patients treated for ACS, further contributing to late strut malapposition. In a study by intravascular ultrasound at long-term follow-up, late acquired malapposition could be attributed to positive vessel remodeling and/or plaque/ thrombus resolution.22 In a meta-analysis of 17 studies with intravascular ultrasound performed at 6 to 9 months, the risk of (very) late ST was sixfold higher in patients with, versus those without, late malapposition (late acquired or persistent).23 Moreover, in 2 recent studies by optical coherence tomography, strut malapposition was the most common identifiable mechanism in patients presenting by late and very late ST after drug-eluting stent implantation.24,25

The BASE ACS trial was not designed a priori to explore specific differences in outcome based on PD following the index procedure. Because of the retrospective nature of this post hoc analysis, some data relevant to the outcome might have been missed. In addition, the trial cohort is under- powered for specific subgroup analysis. Moreover, analysis of patient data in 1 subgroup that includes different stent designs should be interpreted with caution. Furthermore, the current post hoc analysis was a nonrandomized subgroup analysis: the trial cohort was not randomized based on the

index subgroup analysis (PD versus non-PD), but instead, PD was performed ad hoc, based on operator decision; this might limit the conclusiveness of the results. Finally, medication use was reported only at baseline, but not at different time points of follow-up; this might have potential effect on the results.

Acknowledgment: The authors thank Tuija Vasankari, Eija Niemelä, and Minna Ampio for their support in the conduct of this study.

Disclosures

The authors declare that there is no conflict of interest. The current post hoc analysis received no grants from any funding agency in the public, commercial, or not-for-profit sectors.

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