Primary Angioplasty Without On-site Surgical Back-up: The First Experience with Mobile Catherization Facility

Multi-center randomized trials indicate that primary angioplasty in acute myocardial infarction (AMI) lowers the rates of death, stroke, recurrent ischemia and re-infarction compared with fibrinolytic therapy.¹ For low-risk patients with AMI, the mortality of primary angioplasty can be very low (2 Furthermore, most AMI patients included in these studies were not candidates for fibrinolytic therapy, either because they had bleeding risks or shock, or did not have diagnostic electrocardiograms.³ These subgroups of patients may be at higher risk than those eligible to receive fibrinolytic therapy. The invasive approach can be applied to almost all of these patients at capable centers. Moreover, primary angioplasty may be more cost-effective than fibrinolytic therapy. The topic of debate is the safety issue of angioplasty performed in centers without surgical back-up. Although angioplasty is recommended for the management of AMI and refractory unstable angina, less than 10% of European hospitals are equipped with percutaneous coronary intervention (PCI) facilities, some are equipped with mobile fluoroscopy machines and even less have on-site cardiac surgery back-up.^4,5 As the extension of the indications for coronary angioplasty increases, the need for extension of the reference areas increase. It thus becomes increasingly important for both clinical and economic reasons to address the question of whether interventional approaches to the treatment of AMI can be extended safely and effectively to a larger number of hospitals, including those without on-site surgical back-up. This issue is especially important for underdeveloped countries where cardiology centers with interventional capabilities are rare and are found only in heavily populated cities. People living in remote areas, thus, cannot be treated with interventional techniques. The present study analyzes the safety and efficacy of therapeutic interventions performed in a center without surgical back-up. Patients and Methods Laboratory and operators. The fluoroscopy machine is a Siemens C-800 Powermobil (Erlangen, Germany) with an x-ray generator with a maximum 20 kW output. An ambulance was maintained for urgent transport reasons. A tertiary center (Kosuyolu Heart Center, located approximately 200 kilometers, or 160 miles away) with a 24-hour cardiovascular surgery service was informed for urgent cases. The catheterization laboratory is well equipped with resuscitative equipment and well stocked with a broad array of interventional equipment. Primary angioplasty procedures were performed by two experienced operators. They had performed more than 500 PCI procedures from January 1998 to December 2000 as primary operators before they started working in the department where the study was performed. The nursing and technical catheterization laboratory staff are experienced in handling acutely ill patients and are comfortable with interventional equipment. They have participated in PCI procedures on a 24-hour, 365-day call schedule. The cardiac care unit nurses were trained for hemodynamic monitoring. Patients. Between January 2001 and February 2003, 78 consecutive primary angioplasty procedures were performed at our center. A written consent form informing the patient about the status of the laboratory and possible complications was signed by every patient. Primary angioplasty procedure. The study population with AMI underwent primary angioplasty if they had over 30 minutes of ischemic pain not controlled by conventional medications (aspirin, nitroglycerin, beta-adrenergic blocking agents and heparin, but not fibrinolytic agents) or an ECG demonstrating 2.0 mV of ST-segment elevation in 2 or more contiguous leads. There was no time cut-off if the clinical impression suggested ongoing myocardial necrosis (ongoing chest pain and ST deviation with preserved R-waves in 2 or more infarct leads). Patients who presented more than 12 hours after onset of pain if they were symptom-free upon arrival to the emergency department were considered ineligible for PCI. Post-procedure medication protocol and follow-up. After successful stent implantation, heparin was not routinely administered unless there was a clinical indication, such as a large residual dissection. The sheaths were removed the same day. After sheath removal, experienced technicians performed manual compression of the puncture site, following which a pressure bandage was applied for 6 hours. Ambulation was allowed 6 hours after the sheath was removed. Clopidogrel 75 mg once daily was continued for 4 weeks and aspirin 100–300 mg once daily was continued indefinitely. Electrocardiograms (ECG) were recorded immediately after the procedure, then daily before discharge. If the patient had recurrent chest pain, post-procedure creatine kinase-myocardial band (CK-MB) level was measured and an additional ECG was recorded. The majority of patients were discharged from the intensive care unit 2 days after the procedure. Mean hospital discharge was 6 ± 1 days. Follow-up coronary angiography was performed at 6 months in selected patients, or earlier if clinically indicated. Definitions and angiographic analysis. Quantitative coronary angiographic analysis was performed using the quantitative coronary analysis system (AET-med SPA, Italy). Angiographic measurements were obtained during end-diastole using the image that showed the greatest narrowing without overlap and with the least degree of foreshortening. Intracoronary nitroglycerin was administered at baseline and final angiography. Measurements of the reference vessel diameter, minimal lumen diameter (MLD) and percent diameter stenosis were determined by average of 2 orthogonal views. The index reference diameter was the average of proximal and distal reference vessel diameters. Lesion length was measured on the baseline angiography using the “shoulder-to-shoulder” definition. Changes in MLD were expressed as acute gain (post-procedural MLD minus pre-procedural MLD), late loss (post-procedural MLD minus 6-month follow-up MLD), and loss index (late loss/acute gain). Angiographic restenosis was defined as renarrowing of the target lesion > 50%. Q-wave myocardial infarction (MI) was defined as the development of new abnormal Q-waves not present at the baseline in association with CK-MB enzyme elevation of 3 times the upper normal limit, and non-Q-wave myocardial infarction was defined as CK and CK-MB elevation of 3 times the upper normal limit. Device success rate was defined as advancing the guidewire through the culprit lesion and dilating the lesion by balloon or stent. Angiographic success was defined as >= 50% reduction in the diameter of the stenosis with distal TIMI 3 flow. Procedural success was defined as angiographic success without the occurrence of any major ischemic complications during hospitalization. A suboptimal result was defined as a 30–50% residual stenosis after coronary angioplasty with TIMI 3 flow. Restenosis was defined as the occurrence of > 50% stenosis at the site of angioplasty, or clinical evidence of ischemia in the area of the dilated vessel. Complications. Major ischemic complications were defined as the occurrence of MI, death or the need for emergency coronary artery bypass grafting. The patients were screened for major ischemic complications and stroke during follow-up. Data collection and statistics. Demographic, clinical and technical data were gathered prospectively. Follow-up coronary angiography was performed 6 months post-procedure. Statistical analysis was performed with SPSS 10.0 for Windows (Statistical Package for Social Sciences). Continuous variables are expressed as mean ± SD. Results Baseline clinical and angiographic data on the patients who underwent primary angioplasty are summarized in Table 1. There was a high proportion of patients with hypertension (21%) and diabetes mellitus (33%). In 6 out of 78 patients, the guidewire could not be passed distal to the lesion; therefore, the device success rate was 92.3%. In 31 out of 72 patients, direct stenting was feasible (43%). The mean pressure used for stent deployment was 11.4 ± 2.6 atm. There was no incidence of stent loss, stent dislocation, balloon burst before optimal deployment, acute thrombosis, or subacute stent thrombosis. Platelet glycoprotein IIb/IIIa receptor blockers were used in 35 patients (all tirofiban). Control angiography at 6 months could be assessed in 30 patients (at an average of 180 ± 23 days). The binary restenosis rate (50% stenosis at 6-month follow-up) was 13.3 %. Data demonstrated a 1.84 ± 0.46 mm maximum lumen diameter at the end of the study. The acute gain was 1.43 ± 0.48 mm. Mean reference lumen diameter was 2.74 ± 0.42 mm and overall, 62% of the lesions were 7Emergency procedures are also associated with high rates of peri-operative infarction and less frequent use of arterial conduits. Complex intervention, hemodynamic instability, and prolonged time-to-reperfusion are contributing factors to the increased risk of emergency bypass surgery. This data encourage the authors to perform PCI in hospitals without on-site surgery and many studies have reported successful angioplasty series without on-site surgical back-up and a very minimal need for off-site surgery in failed angioplasty. Today’s hot topic is the appropriateness of elective angioplasty in centers without on-site surgical coverage.⁸ PCI was performed in AMI patients by Wharton et al. and in refractory unstable angina by Michalis et al. in hospitals without on-site surgery with excellent results.^9,10 Hayat et al. performed PCI in 117 consecutive patients without any exclusion criteria. Patients were experiencing stable angina, unstable angina and silent ischemia. Angiographic success was 91% with major complications in only 4 patients (1 death, 2 AMI and 1 tamponade) with no need for emergency surgery.¹¹ Smith et al. recommend timely management of ischemic complications, logistics for managing cardiac surgical or vascular complications, and operator/laboratory volumes.¹² Interventional cardiology procedures are associated with complications that are generally inversely related to operator and institutional volume.¹³ Another issue that should be discussed in our study is that all of the procedures were performed with a mobile catheterization system. While the usefulness of this type of machines for coronary angiography has been well documented, the safety and efficacy of PTCA performed with a mobile catheterization facility has been a matter of debate in the interventional cardiology community, mainly because of some of this equipment’s drawbacks. The primary disadvantages include the following: a less effective cooling system which leads to the x-ray tube overheating during longer fluoroscopy sessions — particularly during projections in which the voltage is close to the maximal values; an increased risk of temporary switch-off of the machine due to overheating, followed by the machine turning on, even for as long as several minutes; inferior quality of the images for some projections and for obese patients. The advantages include low cost, feasibility of installation, ease-of-use, a modern digital recording system on CD-ROM in the DICOM system, and the mobility of the apparatus. Reczuch et al. reported a mortality rate of 0.4% and a major adverse cardiac event rate of 0.9% in 687 PCI patients, including AMI patients.¹⁴ The urgent cardiac surgery need was 0%. The major cardiac event rate in the present study is 4 (1%) and the in-hospital mortality rate is the same. These data are compatible with a recent study published by Anderson et al. which is based on PCI data collected and analyzed by the American College of Cardiology’s National Cardiovascular Data Registry from January 1, 1998, through September 30, 2000 and involving 100,292 PCI procedures. This registry reported 77% stent utility and an overall mortality rate of 1.4%.¹⁵ The authors of the present study think that in light of the advancements afforded by new stent technology and drugs, primary coronary angioplasty can be safely performed in all patients with MI — even with the use of mobile catheterization systems.

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