Intracoronary stenting

Myocardial Perfusion SPECT Imaging in Patients after Percutaneous Coronary Intervention

Coronary artery disease (CAD) is the most prevalent form of cardiovascular disease affecting about 13 million Americans, while more than one million percutaneous transluminal intervention (PCI) procedures are performed annually in the USA. The relative high occurrence of restenosis, despite stent implementation, seems to be the primary limitation of PCI. Over the last decades, single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), has proven an invaluable tool for the diagnosis of CAD and patients’ risk stratification, providing useful information regarding the decision about revascularization and is well suited to assess patients after intervention. Information gained from post-intervention MPI is crucial to differentiate patients with angina from those with exo-cardiac chest pain syndromes, to assess peri-intervention myocardial damage, to predict-detect restenosis after PCI, to detect CAD progression in non-revascularized vessels, to evaluate the effects of intervention if required for occupational reasons and to evaluate patients’ long-term prognosis. On the other hand, chest pain and exercise electrocardiography are largely unhelpful in identifying patients at risk after PCI.

Although there are enough published data demonstrating the value of myocardial perfusion SPECT imaging in patients after PCI, there is still debate on whether or not these tests should be performed routinely.

Suppressor of cytokine signaling-3 and intimal hyperplasia in porcine coronary arteries following coronary intervention

AIMS

The growth and differentiation of cells is regulated by cytokines by binding to cell-surface receptors and activating intracellular signal transduction cascade. Suppressor of cytokine signaling (SOCS)-3 is a negative regulator of cytokines. In this study we examined the expression of SOCS-3 in porcine coronary artery smooth muscle cells (PCASMCs) in vitro and in proliferating smooth muscle cells of neointimal lesions after coronary artery intervention in a swine model.

METHODS AND RESULTS

PCASMCs were cultured and stimulated with TNF-α and/or IGF-1 individually or in combination. Protein expression of SOCS-3 was examined using Western blot. For in vivo studies, six female Yucatan miniswine were fed with special high cholesterol diet for 8 months. At 4 months of high cholesterol diet, animals underwent coronary balloon angioplasty. At the end of 8 months animals were euthanized, coronary arteries were isolated and morphological and histological studies were performed. Western blot data revealed significantly high SOCS-3 expression in PCASMCs in the presence of either TNF-α or IGF-1 (5-6 fold) alone. However, in the presence of both TNF-α and IGF-1 the SOCS-3 expression was significantly decreased (4-5 fold). Results from morphological studies including, H&E and Masson's trichrome stain showed typical lesions with significant neointimal proliferation. Histological evaluation showed expression of smooth muscle α-actin and significantly increased proliferating cell nuclear antigen (PCNA) in neointimal lesion. Interestingly, there was significantly decreased expression of SOCS-3 in smooth muscle cells of neointima as compared to control.

CONCLUSIONS

These data suggest that SOCS-3 expression is decreased in proliferating smooth muscle cells of neointimal lesions. This leads to uncontrolled growth of vascular smooth muscle cells in injured arteries leading to restenosis. Therefore, local delivery of SOCS-3 gene at the site of injury after coronary artery intervention could regulate the proliferation of vascular smooth muscle cells and help in preventing the neointimal hyperplasia and restenosis.

Morphometric analysis of the intimal reaction after stent implantation in iliac arteries submitted to angioplasty in pigs

PURPOSE

To compare through digital morphometry, the intimal thickening of the common ilíac arteries (CIA) in pigs, submitted to angioplasty and angioplasty followed by stent implantation.

METHODS

Angioplasty was performed in 10 pigs in both CIA, followed by a stent implantation in the left CIA. After four weeks, the aorto-iliac segment was dissected. Histologic slices where divided in three groups: left CIA in the area of the proximal (group 1) and distal (group 2) implantation site of the stent and the region of angioplasty in the right CIA (group 3). The histological slices were digitalized to be analyzed by morphometry with calculation of the luminal, intimal and media layers areas. Descriptive statistics analysis was performed through average and standard deviation of areas on each group, using ANOVA, with LSD Post-Hoc test (p<0.05).

RESULTS

A significant statistic difference was observed when the median area of intimal layer of the groups 1 and 2 where compared with group 3 and in the media layer area of the groups 1 and 2 when compared with group 3. No difference was observed in luminal areas among the three groups.

CONCLUSION

Angioplasty followed by stent insertion produces an intimal thickening larger than that observed after simple angioplasty. However, the area of the media layer is smaller in the "angioplasty plus stent" group and there is no significant change in the luminal area among the three groups.

Current Indications, Results, and Technique of Carotid Angioplasty/Stenting

Carotid endarterectomy (CEA) remains the treatment of choice for most patients with high-grade carotid artery stenosis. Certain patient subsets, including those with severe cardiac and pulmonary disease and those with local/anatomic risk factors (including recurrent stenosis following CEA, cervical radiation therapy, prior radical neck dissection, and surgically inaccessible lesions) are at increased risk of stroke, cranial nerve injury and non-Q myocardial infarction following CEA, and may be better served by carotid angioplasty and stenting (CAS). Procedural success is dependent upon proper patient selection and meticulous attention to detail. The use of cerebral embolic protection appears to reduce the risk of peri-procedural stroke following CAS.

The Role of Recombinant Hirudins in the Management of Thrombotic Disorders

Native hirudin is the most potent natural direct thrombin inhibitor currently known; it is capable of inhibiting not only fluid phase, but also clot-bound thrombin. Recombinant technology now allows production of recombinant hirudins (r-hirudins), which are available in sufficient purity and quantity with essentially unaltered thrombin-inhibitory potency. As thrombin is known to play a key role in a number of thrombotic disorders, numerous studies focused on the impact of r-hirudins on the clinical course in these diseases. R-hirudins provided significantly more stable anticoagulation than standard heparin, but demonstrated a relatively narrow therapeutic range with relevant bleeding risk even at clinically effective doses. In doses that are not associated with an increased bleeding risk, r-hirudins often failed to demonstrate significant superiority to heparin. To date, r-hirudins have a definite role in the treatment of heparin-induced thrombocytopenia, where they markedly reduce the high risk of thrombosis. For prophylaxis of deep vein thrombosis, r-hirudins have been shown to be superior to both unfractionated and low molecular weight heparin, but are not extensively used in this indication. In acute coronary syndromes, a definite role of r-hirudins has not yet been firmly established. When applied in an appropriate dose as adjunct to thrombolysis in patients with acute myocardial infarction, randomized, controlled trials did not show a consistent benefit of r-hirudins, especially in the long-term. In patients undergoing coronary balloon angioplasty for acute coronary syndromes, promising effects in the early postprocedural phase did not translate to an improved outcome after 6 months. In patients with unstable angina pectoris, efficacy and safety of r-hirudins as primary antithrombotic therapy are still under debate. In the future, r-hirudins are to be compared with alternative or additional potent antithrombotic agents or treatment strategies. This comparison will ultimately lead to their final placement in the management of thrombotic disorders.

Long-term outcome of patients with silent versus symptomatic ischemia six months after percutaneous coronary intervention and stenting

OBJECTIVES

We sought to evaluate the incidence of silent ischemia versus symptomatic ischemia six months after percutaneous coronary intervention (PCI) and its impact on prognosis and to test the utility of myocardial perfusion single-photon emission computed tomography (SPECT), or MPS, for risk stratification in these patients.

BACKGROUND

Silent ischemia is frequent after PCI. However, little is known about silent ischemia and long-term outcome after PCI and stenting.

METHODS

In 356 consecutive patients with successful PCI and stenting and follow-up MPS after six months, long-term follow-up (4.1 +/- 0.3 years) was performed. The MPS images were interpreted by defining summed stress, rest, and difference scores (summed difference score [SDS] = extent of ischemia) and related to symptoms and outcome. Critical events included cardiac death, myocardial infarction, and target vessel revascularization.

RESULTS

Eighty-one patients (23%) had evidence of target vessel ischemia, which was silent in 62%. The only independent predictor of silent ischemia was SDS (odds ratio 0.64, p = 0.001). During follow-up, 67 critical events occurred. For patients with an SDS of 0, 1-4, and >4, the critical event rates were 17%, 29%, and 69%, respectively. Similarly, patients without ischemia, silent ischemia, and symptomatic ischemia had 17%, 32%, and 52% of critical events, respectively. Diabetes (relative risk 1.98, p = 0.03) and SDS (relative risk 1.2, p < 0.001) were independent predictors of critical events. The MPS image added incremental information for the prediction of critical events.

CONCLUSIONS

Six months after PCI and stenting, 23% of patients had target vessel ischemia, which was silent in 62%. Silent ischemia predicted a worse outcome than did no ischemia and tended to have a better outcome than symptomatic ischemia. This was closely related to the extent of ischemia. The SDS added incremental value to pre-scan findings with respect to diagnosis and prognosis, indicating the utility of MPS for risk stratification after PCI and stenting.

Randomized comparison of J&J Crown stent versus NIR stent after routine coronary angioplasty

BACKGROUND

Coronary artery stents are used for the treatment of acute or threatening vessel occlusion complicating coronary angioplasty or for prevention of restenosis after angioplasty. The current randomized trial compared the procedural outcome and long-term patency of 2 different flexible stents in unselected lesion morphology.

METHODS

The study population consisted of consecutive patients undergoing coronary angioplasty for symptomatic coronary artery disease followed by high-pressure stent implantation. The poststent treatment consisted of antiplatelet therapy. The primary hypothesis was an assumed restenosis rate of 30% in the group receiving NIR stents (Boston Scientific Europe SPRL, Parc Industriel de Petit-Rechain, Belgium) and a reduction of the restenosis rate (defined as >50% vessel diameter at follow-up) by 50% in the group undergoing J&J Crown stent (Cordis, Johnson & Johnson Interventional Systems, Warren, NJ) implantation: the restenosis rate and minimal luminal diameter at follow-up. Follow-up angiography was performed 6 months after the initial procedure.

RESULTS

A total of 203 patients were randomized to receive either the J&J Crown stent (n = 103) or the NIR stent (n = 100). The procedural success was similar in both groups (96.1% vs 99% in the NIR stent group, respectively; P =.19). There were 4 cases of crossover from the J&J Crown to the NIR stent group. In one patient, stent implantation of either stent model did not succeed. One patient died from fulminant pulmonary embolism. Restenosis, defined as >50% diameter stenosis at follow-up 5.8 +/- 1.3 months after the initial procedure occurred in 19 patients (18.4%) in the J&J Crown stent group compared with 22 patients (22.0%) in the NIR stent group (P =.42). There was a significantly higher rate of crossover from the J&J Crown stent to the NIR stent (3.9% vs 0%, respectively, P =.047), whereas reverse crossover did not occur. The one lesion in which NIR stent implantation was not successful had an extremely tortuous proximal part. This patient underwent only balloon angioplasty. Clinical events were rare during 6 months of follow-up and the incidence did not differ between both groups (nonfatal myocardial infarction: J&J Crown stent 1.0% vs 0% in the NIR stent group, P =.32; all-cause mortality: J&J Crown stent 1.0% vs 0% in the NIR stent group, P =.32).

CONCLUSIONS

There were no significant angiographic and clinical differences between the J&J Crown and NIR stents. Both stents had a similar procedural success rate, although the implantation of NIR stents was successful even in vessels in which previous attempts at J&J Crown stent placement had failed.

The role of adenosine 5'-diphosphate receptor blockade in patients with cardiovascular disease

Aspirin, which has been the mainstay of antiplatelet agent for many decades, affects a single pathway in the platelet activation process and provides incomplete protection against cardiovascular events. Aspirin also may blunt the hemodynamic effect of angiotensin-converting enzyme inhibitors. Dipyridamole may provide some additional benefit, but there is little evidence to suggest its superiority alone or in combination with aspirin compared to standard doses of aspirin. Oral platelet glycoprotein IIb/IIIa inhibitors, although initially promising, have had disappointing results in recent clinical studies. A new class of medications, the thienopyridines, blocks the activity of platelet adenosine 5'-diphosphate (ADP) receptors, thereby reducing platelet activation. This review discusses the pharmacology, clinical studies, and potential uses of these agents, which include ticlopidine and clopidogrel. ADP inhibitors, by blocking an alternate pathway of platelet activation, are slightly more effective than aspirin in reducing cardiovascular events.

Common sense and figures: the rhetoric of validity in medicine (Bradford Hill Memorial Lecture 1999)

Austin Bradford Hill was once a friend to The Lancet, but, as occasionally happens, friends fall out. The great legacy of his association with the journal, however, was Principles of Medical Statistics. As each edition was succeeded by another--the first in 1937, the last in 1991--he seemed to shift his view about the influence of statistical method on clinical practice from one of assured certainty to one of modest advantage. That change paralleled a move away from an emphasis on the importance of internal validity in the randomized trial to one of understanding the inescapably practical significance of generalizability. Writers on medical research have explored notions of external validity in various ways. One view, for example, is to seek a close correlation between the participants in a clinical trial and patients seen in practice. The argument goes that such a correspondence has to be made before any decision can be taken about whether to apply the result of that trial to the clinical setting. Another view, first worked out by the American logician Charles Sanders Peirce, is that one must simply rely on the informed guess, based on a reasonable estimate of the limits of extrapolation. The tensions between and implications of these two different approaches are worked through using the example of coronary stents. A solution is, perhaps, to write explicit rules of interpretation that provide a framework for judging the strength of a claim to applicability. Five questions are posed, which try to lay a foundation for such a framework.

Coronary artery stents: review and patient-management recommendations

BACKGROUND

Coronary artery stents are metallic scaffold devices that physically support narrowed coronary arteries to alleviate symptoms of ischemic coronary artery disease. They are placed during invasive procedures similar to that of percutaneous transluminal coronary angioplasty, and patients are maintained with antiplatelet medications to lessen the chances of stent stenosis.

METHODS

The authors provide a brief overview of coronary artery stents and discuss the dental management of patients who have received stents.

CONCLUSIONS

After stent placement, patients usually are maintained with antiplatelet regimens, which may necessitate choosing medications that do not potentiate their effects. Any discussion as to the possible need for antibiotic prophylaxis of patients with stents largely is missing from the literature. Recent literature, however, indicates that antibiotic prophylaxis, if required, may only be needed during the first few weeks after stent placement.

CLINICAL IMPLICATIONS

Dental professionals should become knowledgeable about coronary artery stents. Although these devices have a higher success rate than other procedures in alleviating symptoms of ischemic coronary artery disease, some patients are still at risk of experiencing significant cardiac events.

Procedural results and intermediate clinical outcomes after multiple saphenous vein graft stenting

OBJECTIVES

We evaluated the early and mid-term (18-month) clinical events in a consecutive series of patients undergoing a nonstaged multiple saphenous vein grafting (SVG) intervention with stents as compared with a single SVG stent procedure.

BACKGROUND

Saphenous vein graft angioplasty has been limited by high rates of distal embolization, myocardial infarction, restenosis and late mortality. It is unknown whether stenting of multiple, different SVGs at the same setting is associated with higher risk.

METHODS

We evaluated in-hospital and mid-term clinical outcomes (death, Q wave myocardial infarction [MI] and repeat revascularization rates up to 18 months) in 70 consecutive patients treated with coronary stents in 2 (93% of patients) or 3 SVGs, as compared with 649 patients undergoing stenting of a single SVG between January 1, 1994 and December 31, 1997.

RESULTS

Overall procedural success was obtained in 97% of patients with 2 or 3 SVGs and 97% of patients with a single SVG (p = 0.94). Procedural complications were also similar (2.8% for multiple SVGs vs. 2.7% for a single SVG, p = 0.94). There was a higher prevalence of periprocedural non-Q wave MI (28% vs. 16%, p = 0.009) in the multiple SVG group. During follow-up (18 months), target lesion revascularization was 11% in multiple SVG and 15% in single SVG interventions (p = 0.19), and repeat revascularization (calculated per treated patient) was also similar for both groups (19% vs. 18%, p = 0.94). There was no difference in death (5.6% vs. 5.3%, p = 0.92) and Q wave MI rate (4.3% vs. 2.9%, p = 0.55) after the multiple SVG intervention. Overall cardiac event-free survival was similar for both groups (62% vs. 60%, p = 0.75). The study was powered to detect a clinically meaningful difference of 10% in mortality; smaller differences could not be evaluated on the basis of this sample size.

CONCLUSIONS

Simultaneous stenting of multiple SVGs in carefully selected patients has similar in-hospital procedural success and major complications rates, as well as mid-term (18-month) clinical outcomes, as compared with single SVG stenting. Thus, multiple SVG interventions using stents may be a viable revascularization strategy for carefully selected patients and suitable lesions in multiple SVG disease.

Gene therapy for restenosis

This review provides an overview of candidate genes that are currently being evaluated for genetic strategies in vascular gene therapy. We discuss treatment strategies that have proven efficacious in limiting postinterventional restenosis through evaluation with in vivo model systems. The candidate strategies utilize genes that are either cytotoxic, regulate vascular smooth muscle cell differentiation or proliferation. In addition, we review oligonuclotide and ribozyme strategies that function by suppressing the expression of cell cycle regulators.

Myocardial Hematoma Documented by Transthoracic Echocardiography After Sequential Coronary Artery Stenting

We report the case of a patient who deteriorated suddenly while undergoing endoluminal coronary artery reconstruction with multiple stents to the left anterior descending coronary artery. With the aid of transthoracic echocardiography, a pericardial effusion was noted; however, dissection of the ventricular wall due to a large myocardial hematoma was also identified. Emergency exploration with evacuation of the pericardial blood with coronary artery bypass graft surgery was successfully accomplished. We discuss the possible factors that could have been associated with this unforeseen complication and the potential benefit of transthoracic echocardiography in early recognition.

Corrective use of the 2.5-mm GFX stent for suboptimal angioplasty results in small coronary arteries

To evaluate the clinical efficacy of endoluminal stenting in the setting of percutaneous intervention for small coronary artery lesions, we reviewed our results on stenting with the 2.5-mm GFX stent (Arterial Vascular Engineering, Santa Rosa, CA) during an 18-month study period. A total of 120 patients with significant coronary artery disease in vessels </=2.6 mm were followed up clinically. Procedural success (defined as angiographic residual stenosis <20% without clinical complications) was obtained in 94% of cases. In-hospital complications were death (1%), non-Q-wave myocardial infarction (5%), and urgent repeat percutaneous intervention because of stent thrombosis (3%). During a mean follow-up of 9.8 months (range, 6-23 months), the following complications were noted: myocardial infarction (1%), clinical need for repeat intervention (13%) requiring repeat percutaneous treatment (12%) and surgical revascularization (1%). In conclusion, transcatheter application of a specifically designed stent for coronary artery disease in small vessels seems safe and efficient with a low incidence of adverse events during follow-up. Cathet. Cardiovasc. Intervent. 48:157-161, 1999.

Preliminary experience with the V-flex plus coronary stent: immediate and one-month clinical outcome

Procedural and 1-month outcome data following implantation of the V-Flex Plus stent in our first 54 consecutive patients (35 male; mean age, 62 years) are described. Sixty-four stents were implanted for 60 mainly complex lesions; 48% were left anterior descending; 20%, circumflex; 27%, right coronary artery; and 5%, saphenous vein graft. The Indication for stenting was elective in half of the patients and for a suboptimal result or as a bailout procedure in the other half. The stents were deployed at a mean of 12 atm (range, 6-18) and postdilatated to a mean of 15 atm (range, 8-20). Pre- and postdilatation balloon sizes were 2.96 +/- 0.57 mm and 3.16 +/- 0.34 mm, respectively. The procedural success rate was 98%. There were no deaths or Q-wave myocardial infarctions. One patient suffered a non-Q-wave myocardial infarction and another developed a femoral false aneurysm. At 1-month follow-up, there were no additional events, in particular no revascularization procedures. Eighty-nine percent of patients were free of angina. Implantation of the V-Flex Plus stent is safe and effective with an excellent early success rate comparable to that of published randomized trials and registries of carefully selected patients.

Coronary artery surgery: the end of the beginning

In each of the first three decades of myocardial revascularization, conventional treatment has been revised completely. This lecture comments on three areas of discovery that have shaped the evolution of myocardial revascularization: science, technology development, and revascularization. The discoveries in all three areas are inexorably interrelated. The single greatest lesson learned so far is that conduit performance carries more prognostic weight than any other factor. We have observed that vein graft atherosclerosis is predictable, and that the first-generation lipid lowering drugs have a favorable effect in patients who achieve marked LDL reduction. Biologically better revascularization begins with use of the internal thoracic artery for grafting to the anterior descending coronary artery. As the results of internal thoracic artery grafting are widely reported, arterial bypass revascularization has expanded, notably by radial and gastroepiploic arteries. The results of bilateral internal thoracic artery grafting are discussed, including large-scale registry results of internal thoracic artery usage in the United States. The internal thoracic artery is significantly underutilized. Diabetes affects both endoluminal and surgical revascularization. The new pharmacology in cardiology interventions shows promise in diminishing restenosis and thrombosis even in diabetic patients. Conversely, extended internal thoracic artery grafting may also benefit diabetic patients. Now we are entering a new age of minimally invasive coronary surgery. We have passed through the early stages of mini-thoracotomy, and we are moving on to access through 1-cm ports, intrathoracic cannulation, antegrade and retrograde myocardial protection, and computer guided three-dimensional vision and instrumentation. The potential for robotic control adds greater precision, ease of use, and safety. This new technology will be integrated with diagnostic information, intraoperative monitoring, anesthesia and perfusion data, cost accounting, and surgical note transcription. The operating room of the future will package intraoperative information and is adaptable to all surgical specialties. The future of coronary artery surgery will depend on minimally invasive techniques, all-arterial grafting, and selective lipid modification to reduce progressive atherosclerosis. The conclusion of this decade marks the end of the beginning. The new generation of cardiothoracic surgeons will share in an array of technology and research unmatched in previous decades.