Influence of catheter technology and adjuvant medication on acute complications in percutaneous coronary angioplasty

Arterial wall thermography

An atherosclerotic plaque is considered vulnerable when it is at higher risk of inducing acute cardiac events. The early detection and follow-up of the vulnerable plaque are crucial to prevent these events from happening. To date there are no proven techniques to detect such a plaque. Arterial wall thermography, tracing the heat signature of the activated macrophages, is a new and promising method in this direction. However, the difficulties of applying such a method in vivo should not be neglected. Current science proposes several potential thermographic methods. They can be generally categorized as noninvasive and invasive. Magnetic resonance thermometry (MRT) is the most important noninvasive method. It is novel, accurate, and reproducible, but is unfortunately hampered by resolution limitations due to the size and motion of the target vessels. The "infrared" and the "contact-sensor" are the most important invasive thermographic methods. Mainly due to the difficulties of infrared radiation in penetrating the flowing blood, the contact thermographic methods seem to be the most feasible at present. The superiority of thermal mapping of the arterial wall versus the localized temperature measurements is clear. The use of multiple thermal sensors arranged around the vessel's circumference and the application of motorized catheter pullback, not only ensure a large area of coverage, but also enable us to build thermal maps and vascular thermoanatomical reconstructions by using modern computer technology. It is expected that arterial thermography will undoubtedly initiate debate, mainly concerning the most appropriate therapy for the vulnerable plaque. Data collection and correct interpretation are expected to lead us into making wise decisions.

Aggressive intervention for myocardial infarction: angioplasty, stents, and intra-aortic balloon pumping

Primary percutaneous transluminal coronary angioplasty (PTCA) is not used in all hospitals capable of performing it because the data regarding results are either not known or not easily interpreted. Unlike pharmaceutical trials, which receive $30-50 million in research funds, virtually all trials of PTCA have been unfunded. Nevertheless, several groups have conclusively proved the benefit of primary PTCA over thrombolysis. In a 1995 meta-analysis, PTCA proved superior to thrombolytic therapy in reducing death and reinfarction. The Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-IIB) substudy confirmed this fact with 94% certainly. Other studies were designed to refine the angioplasty technique. In the Primary Angioplasty in Myocardial Infarction (PAMI-I) study, acute catheterization was used to stratify patients and identified a low-risk population whose mortality equaled that of patients treated electively. Compared with clinical risk factors, angiographic findings enhanced the power to predict mortality three-fold. The high-risk subset with acute myocardial infarction (MI) was also randomized to treatment with or without prophylactic intra-aortic balloon pumping (IABP). Although IABP caused no complications, it had no positive effect on primary endpoints (death, recurrent MI, and reocclusion) and did not improve left ventricular function at 6 months. One limitation of primary PTCA is a high rate of late restenosis (30-50% at 6 months). In a pilot study we are examining the role of stents in conjunction with primary PTCA. Early results indicate that in the 69% of patients eligible for stent placement, in-hospital events were uncommon (no deaths, no reinfarctions, low rate of recurrent ischemia) and the need for repeat revascularization was infrequent.

Coronary stenting for acute myocardial infarction

In summary, our experience suggests that coronary stents may play a useful role in carefully selected patients undergoing angioplasty for myocardial infarction. The potential may exist to increase rates of successful infarct artery reperfusion and increase long-term patency. The use of stents in myocardial infarction should probably be reserved for situations in which balloon angioplasty fails. Newer stent designs and anticoagulant regimens may alleviate some of the current concerns with regard to stenting at the time of acute myocardial infarction.

Efficacy of adjunctive thrombolytic therapy in percutaneous transluminal coronary angioplasty

Adjunctive thrombolysis has not been shown to improve angioplasty success or complication rates in elective angioplasty or myocardial infarction and may be detrimental in unstable angina. Thrombolysis of chronically occluded vessels achieves recanalization at a rate comparable to conventional angioplasty and is associated with a high rate of complications and limited long-term patency. Thrombolysis administered for thrombus or acute occlusion complicating angioplasty usually achieves coronary artery patency but is unable to forestall complications in many cases. A benefit of thrombolysis in reducing restenosis has not been conclusively demonstrated.

Changing trends for surgical standby in patients undergoing percutaneous transluminal coronary angioplasty

In 1988 the American College of Cardiology/American Heart Association (ACC/AHA) task force subcommittee on Guidelines for Percutaneous Transluminal Coronary Angioplasty (PTCA) recommended that an experienced cardiovascular surgical team be available within the institution for emergency surgery for all angioplasty procedures. The subcommittee felt strongly that this requirement allowed for no exception, stating that it could not condone existing arrangements that required the transportation of patients to off-site surgical facilities for emergency cardiac surgery. Such arrangements failed to meet the necessary standards of care exercised by prudent physicians. Interventional cardiologists are recognizing that it may be prudent for the ACC/AHA task force to revise its 1988 guidelines. Improved operator technique and new technologic advances, such as lasers, atherectomy devices, stents, and perfusion pumps and balloons, have helped extend the reach of PTCA to more seriously ill patients. With new technologies for angioplasty and an increased awareness of risk factors, active standby can be markedly reduced, thereby resulting in enormous cost reductions and in more appropriate patient care.