Direct Stent Implantation in Acute Coronary Syndrome

Intracoronary stents have been a major milestone in interventional cardiology ever since two large, randomized trials1,2 documented that they reduced restenosis and repeat revascularization rates and increased event-free survival at 6 months. Recent improvements in stent implantation techniques3 and a combination of potent antiplatelet agents,4 such as glycoprotein IIb/IIIa inhibitors, have led to a dramatic improvement in success rate, justifying the stenting of most patients undergoing intervention, even when it is performed in thrombus-containing lesions (which are no longer regarded as lesions for stenting). However, no-reflow may still occur after stenting with predilatation and significantly limit the clinical benefit of the procedure in patients with acute coronary syndrome (ACS).5,6 Standard stent implantation techniques require routine predilatation of the lesion with a balloon catheter to allow easy and uncomplicated passage of the stent, and subsequent complete expansion after deployment. With the improvements in stent design, deployment of stents without balloon predilatation (“direct stenting”) has become more widespread. Despite the increased frequency of direct stenting, the immediate procedural and long-term results are not well documented in ACS patients. Thus, we undertook a prospective randomized study to evaluate the feasibility and safety of direct stenting and compare it with conventional implantation techniques (stenting with predilatation) with respect to in-hospital, 1-month, and 6-month outcomes in patients with ACS. METHODS Patient selection. Between January 2001 and August 2002, a total of 840 patients with ACS underwent percutaneous coronary interventions at our institution. Patients with lesions located in vessels that had excessive proximal tortuosity and those with highly calcified target lesions were excluded. Patients who underwent multivessel procedures (i.e., single-vessel direct stenting plus “traditional” angioplasty and/or stenting on other vessels) were also excluded. Total occlusions [Thrombolysis in Myocardial Infarction (TIMI) 0] were treated by direct stenting only when the infarct-related lesion was clearly identified after the guidewire was passed through the thrombus (TIMI >= 1). The primary endpoint of the study was the rate of major adverse clinical events (MACE;death, acute myocardial infarction and repeat revascularization) in-hospital, at 1 month and at 6 months; the secondary endpoints included the no-reflow phenomenon, balloon inflation time (BIT), number of balloon inflations (NBI), radiation exposure time (RET), and amount of contrast dye used (ACD). The no-reflow phenomenon, which was assessed by three operators who independently reviewed the coronary angiograms and were unaware of the study protocol, was defined as an acute reduction in flow (TIMI Invasive procedure. Coronary angiography was performed with the Judkin’s technique from the right femoral artery. Coronary lesions were assessed by multiple orthogonal views with coronary angiography and visually evaluated for morphologic features similar to those reported by the American College of Cardiology/American Heart Association.7 Stent implantations were performed by three different invasive cardiologists according to standard clinical practice. A 6 French guiding catheter was used in all patients on whom coronary intervention was decided during the coronary angiography. A standard 0.014´´ guidewire was passed through the target lesion. The decision whether to perform predilatation for other lesions that were suitable for both procedures (stenting with or without predilatation) was made by the operator. If a decision was made to proceed without predilatation, the stent was usually deployed at the nominal pressure of the stent balloon and a high-pressure balloon was subsequently used for dilatation within the stent to 14–16 atmospheres (atm). If the stent failed to cross the lesion, standard predilatation with a balloon was performed followed by a further attempt to cross with the stent. If a decision was made to proceed with predilatation, balloon dilatation with 8 atm was performed and stent(s) were subsequently deployed. Results before and after coronary interventions were evaluated quantitatively by coronary angiography (Philips DC). Angiographic success was defined as Medical therapy. All patients received the standard treatment for ACS. Of 145 patients, thirty-five with unstable angina or non-Q wave myocardial infarction were given tirofiban and 16 with Q-wave myocardial infarction were given accelerated tissue-plasminogen activator. Intravenous heparin (10,000 U) was administered at the beginning of the procedure, followed by additional boluses as needed to maintain activated clotting time (ACT) > 300 seconds. ACT was held between 200 and 250 seconds in patients who were given glycoprotein IIb/IIIa receptor antagonists. Intracoronary nitroglycerin 0.1–0.3 mg was given liberally during the procedure. After stenting, all patients received either ticlopidine (500 mg/day) or clopidogrel (300 mg/day as a loading dose immediately before or during the procedure, followed by 75 mg daily) in addition to standard treatment for ACS. Ticlopidine and clopidogrel were discontinued after 1 month. Electrocardiographic monitoring. All patients were monitored continuously during the intervention and then transferred to an intensive care unit after the procedure. A 12-lead electrocardiogram was taken just before and immediately after coronary stenting for exclusion of acute ischemia. A significant ST-segment depression was defined as horizontal or downsloping depression of the ST-segment > 0.1 mV and 0.08 seconds after the J point that persisted more than 1 minute. Clinical follow-up. All patients were followed during the hospital stay and then with telephone contact during the first month and up to six months with respect to MACE (death, acute myocardial infarction, percutaneous coronary intervention or bypass surgery). Deaths were classified as being of cardiac origin if associated with congestive heart failure, acute myocardial infarction, or sudden cardiac death (= 0.1 mV; and increase in serum CK or CK-MB activity. Cardiac enzymes were measured only in cases of: 1) transient or permanent vessel or sidebranch occlusion during the procedure; 2) prolonged changes after the successful procedure; and 3) electrocardiographic changes with or without chest pain. Coronary angiography was performed only in patients with symptoms or signs of ischemia. Statistical analysis. Continuous variables were expressed as means ± standard deviation and were compared by student’s t-test. Categoric variables were compared with the Chi-square test. Comparisons were made between the direct stenting group and the stenting with predilatation group. A p-value Clinical outcomes: Primary study endpoints. Seven patients with Q-wave myocardial infarction in group I and 4 patients with Q-wave myocardial infarction in group II underwent primary percutaneous transluminal coronary angioplasty (PTCA) and stent implantation. A total of 169 lesions were treated with a 153 stents (75 stents in group I and 78 stents in group II). Of the 153 stents, sixty-two were Multi-Link Tristar or Tetra, sixty-five were Hexacath, sixteen were Jostent and 10 were AVE GFX stents. Baseline angiographic features of the two groups were similar. The study population was well matched with respect to baseline angiographic features as shown in Table 2. Clinical outcomes: Secondary study endpoints. The RET, total BIT, and NBI were significantly lower in group I than in group II (p

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