Darren L. Walters

Acute coronary syndrome is a common clinical presentation of in-stent restenosis ☆

Coronary stents have been the major advancement in percutaneous coronary intervention in the last decade and are used in 60% to 80% of patients. However, in-stent restenosis continues to be a problem, occurring in 20% to 30% of cases. The clinical presentation of patients who develop restenosis after stenting has not been well characterized. In this study we compared the clinical presentation of in-stent restenosis with that of restenosis without stenting. Of 739 patients who underwent percutaneous coronary intervention and had repeat catheterization between October 1, 1997, and June 30, 2000, 262 consecutive patients with recurrent ischemia and restenosis were identified: 191 patients with (group A) and 71 without (Group B) stenting. Patients who underwent interventions in bypass grafts and those who developed early acute stent thrombosis were excluded from the study. Recurrent clinical ischemia occurred at a mean of 5.5 months in group A and 6.5 months in group B (p = 0.24). Rest angina (Braunwald class II and III) was more frequent in group A (48% vs 32%, p = 0.032). Acute coronary syndromes, the combination of rest angina, and acute myocardial infarction were also more frequent in group A (68% vs 46%, p = 0.03). Patients in group A were more likely to have angiographically visible thrombus than those in group B (9% vs 0%, p = 0.02). Thus, acute coronary syndromes are a common clinical presentation of restenosis among patients whose follow-up angiogram is obtained for clinical reasons, and occur more frequently in patients with in-stent restenosis than in those with restenosis without stenting.

Heparin-induced thrombocytopenia: a common complication in cardiac transplant recipients.

BACKGROUNDnHeparin-induced thrombocytopenia (HIT) is an idiosyncratic complication of heparin therapy triggered by the development of immunoglobulin G (IgG) antibodies to platelet factor 4 heparin. It typically results in a 50% decrease in platelet count. Paradoxically, although bleeding is rare, there is a high risk of venous or arterial thrombotic events. Given that many patients awaiting transplantation are exposed to heparin for prolonged periods, we sought to determine the frequency of HIT and its consequences among patients before and after cardiac transplantation.nnnMETHODSnWe reviewed retrospectively the clinical, pathologic, and laboratory databases for all patients who underwent heart transplantation at our institution between January 1, 1998, and December 31, 2000. An enzyme-linked immunoabsorption assay (ELISA) that detected IgG, IgA, and IgM antibodies directed against platelet factor 4 heparin complex confirmed the diagnosis of HIT. We analyzed bleeding and thrombotic complications and determined the influence of HIT on post-transplant outcomes.nnnRESULTSnAn assay for HIT antibody was performed before or after transplantation in 26 of 46 patients (46% of the entire cohort). In all cases, the clinical indication for testing was thrombocytopenia. Among patients screened, HIT antibody was detected in 11 patients (39%); HIT developed in 10 of 11 patients before transplantation. The mean platelet count at diagnosis was 88,000 +/- 22,000/mm(3). Heparin-induced thrombocytopenia with thrombosis syndrome developed in 5 of 11 patients (45%). Manifestations included splenic and renal infarctions, renal artery occlusion, coronary artery embolism with myocardial infarction, pulmonary embolism, and femoral and jugular venous occlusions. Alternative pre-operative anti-coagulation included lepirudin (n = 7), argatroban (n = 1), dalteparin (n = 1), and abciximab (n = 1). Two deaths occurred in the HIT-positive group; neither bleeding nor thrombosis caused either death. Actuarial 36-month survival did not differ between HIT-positive and HIT-negative cohorts (78% and 79%, respectively).nnnCONCLUSIONnHeparin-induced thrombocytopenia is a frequent complication among patients hospitalized for heart failure who are awaiting heart transplantation. Timely HIT-antibody screening and the use of alternative forms of systemic anti-coagulation may permit successful transplantation with intermediate survival rates comparable to those of HIT-negative recipients.

Spontaneous Coronary Artery Dissection Utility of Intravascular Ultrasound and Optical Coherence Tomography During Percutaneous Coronary Intervention

Spontaneous coronary artery dissection (SCAD) is an infrequent cause of acute coronary syndromes but is represented disproportionately in young female patients. No specific guidelines exist concerning the appropriate treatment (medical therapy, intracoronary stents, coronary bypass surgery) or the optimal type of stents in otherwise atheroma-free vessels. The role of intracoronary imaging with intravascular ultrasound (IVUS) and optical coherence tomography (OCT) has yet to be fully established.nnA 39-year-old woman with no traditional risk factors for coronary artery disease presented with an anterior ST-segment elevation myocardial infarct after undergoing rigorous aerobic exercises. The patient was gravida 3 para 3, not known to be pregnant, and not postmenopausal. Her last pregnancy was 5 years earlier, and subsequent β human chorionic gonadotropin was negative. Coronary angiography suggested a long spiral dissection in the left anterior descending artery. Her other coronary arteries were smooth walled with no evidence of atherosclerosis. With ongoing symptoms and persisting ST elevation of the surface …

Transthoracic left ventricular puncture for the assessment of patients with aortic and mitral valve prostheses: The Massachusetts General Hospital experience, 1989–2000

Accurate assessment of suspected prosthetic valve dysfunction is critically important as reoperation carries high risk. Noninvasive methods of hemodynamic assessment of patients with both aortic and mitral mechanical valves continue to be frustrated by the interference created by prosthetic material and direct left ventricular puncture may be required for definitive hemodynamic assessment. We report the hemodynamic and angiographic results and outcomes of 38 consecutive patients with double valve replacement who underwent left ventricular puncture as part of evaluation of possible prosthetic dysfunction. These results were compared with those obtained by noninvasive testing. We found noninvasive assessment alone to be unsatisfactory as measurements of regurgitation and stenosis correlated poorly with those obtained by direct left ventricular puncture. Important information that altered patient management was obtained from invasive assessment in 68% of cases with an acceptable rate of complications. Therefore, hemodynamic and angiographic assessment using transthoracic left ventricular puncture should be entertained in patients with mitral and aortic valve replacement presenting with congestive heart failure and suspected prosthesis dysfunction. Cathet Cardiovasc Intervent 2003;58:539–544.

Adjunctive pharmacotherapy for coronary stenting.

The use of coronary stents improves the outcomes of percutaneous coronary intervention (PCI). This has led to a rapid increase in their use. Coronary stenting is not without problems and is complicated by both early ischemic events and late restenosis. The combination of anticoagulation with unfractionated heparin (UFH) and the use of antiplatelet agents including aspirin, thienopyridines, and glycoprotein IIb/IIIa inhibitors has led to a major reduction in early ischemic events after stenting. Low molecular weight heparin (LMWH) and direct thrombin inhibitors have a number of theoretical advantages over UFH. Their role as an adjunct to coronary stenting is still under investigation. Trials of systemic pharmacotherapy aimed at reducing in-stent restenosis have been consistently disappointing. Preliminary results of stents coated with agents that inhibit neointimal proliferation are extremely promising. The results of ongoing phase III trials of these coated stents are eagerly awaited.

The effect of glycoprotein IIb/IIIa receptor inhibitor on the microcirculation in patients undergoing high-risk coronary stenting; a prospective, randomized study.

AbstractObjectives: We evaluated the effect of the glycoprotein IIb/IIIa inhibitor, tirofiban, on the microcirculation measured by Doppler coronary flow reserve (CFR) in patients undergoing high-risk coronary stenting.nBackground: The mechanisms by which glycoprotein IIb/IIIa inhibitors benefit patients undergoing high-risk angioplasty are not fully understood. This may be due to prevention of distal embolization of the coronary clot at the site of angioplasty.nMethods: Thirty two consecutive patients with acute coronary syndrome within 72 hours or with high-risk angiographic features were randomized into 2 groups. Group A (n = 17) received tirofiban (10 μg/kg bolus followed 0.15 μg/kg/min). Group B (n = 15) received placebo bolus and infusion. Coronary flow reserve was measured by Doppler wire technique at baseline, post balloon angioplasty and post-stenting. Platelet aggregation was measured at baseline, 10 minutes, 6 hours and 12 hours post bolus.nResults: There was no significant difference in CFR between the groups at baseline and after balloon angioplasty. Post-stenting CFR, however, was significantly higher in the group pretreated with tirofiban (2.94 vs. 2.25, p = 0.014). The inhibition of platelet aggregation was 94% at 10 minutes, 97% at 6 hours and 94% at 12 hours in the tirofiban group.nConclusion: In patients undergoing high-risk coronary stenting, tirofiban protects and improves the microcirculation measured by Doppler wire technique. This may be due to prevention of distal embolization of clot by tirofiban and explain the clinical benefit.

Indications for Coronary Angiography

Since the first serendipitous selective coronary angiography was performed by pediatric cardiologist Dr. Mason Sones in 1958 during ventriculography and aortography (Sones et al., 1959), invasive coronary angiography has become well established as the diagnostic gold standard for coronary artery disease. Coronary angiography provides definitive information of “luminology” (radiographic outline using a contrast agent) of the coronary arteries. It is the standard with which other diagnostic modalities are compared. Millions are performed annually worldwide. Whilst the risk of coronary angiography of complications is very low in experienced hands the procedure is invasive and, requires dedicated infrastructure and expense. There are certain specific indications for coronary angiography. The general indication for a coronary angiography is to define the coronary artery anatomy. More detailed guidelines for coronary angiography date back to 1999 from the American College of Cardiology (Scanlon et al., 1999). This of course predated the enormous technological advancement over the past decade, the development in computed tomography coronary angiography, the widespread adoption of coronary stenting, the improvement afforded by drug eluting stents, and the availability of new antiplatelet therapy that enhanced the safety of all coronary interventions. This chapter examines the appropriate indications for invasive coronary angiography in the current era, assesses the role of non invasive CT coronary angiography, and incorporates the emerging adjunctive role in the management of patients undergoing percutaneous cardiac structural interventions. Case vignettes are included in this chapter to illustrate the indications and use of coronary angiography in the current era. It must be stressed whilst guidelines do provide recommendations regarding the indications for invasive coronary angiography, many more complex clinical and non clinical factors exist for each individual patient and the clinician must exercise clinical acumen to proceed to perform an invasive diagnostic and/or therapeutic procedure.

The use of mechanical devices as adjuncts to intracoronary stenting.

A number of mechanical adjuncts to intracoronary stenting are now available to the interventional cardiologist. These devices have assisted in the development of a safer and more effective stenting practice. Intravascular ultrasound-guided stenting has been shown to reduce the rate of subacute thrombosis and subsequent restenosis. It allows a greater appreciation of lesion structure and severity so that an appropriate intervention strategy can be devised. Debulking techniques may allow the optimal deployment of stents so that restenosis is reduced; however, the results of large randomized studies are still awaited. The use of thrombectomy and distal embolization protection devices is emerging as a safer alternate to stenting alone in difficult patient subsets, such as those with thrombus-laden lesions and degenerated vein grafts. Doppler and pressure wires may be useful in determining optimal stent deployment and predict subsequent patient outcomes. An understanding of the indications and limitations of these devices is of increasing importance to the interventional cardiologist as the coming decade threatens to yield an impressive array of high-tech innovations.

Improving the Utility of Coronary Angiography: The Use of Adjuvant Imaging and Physiological Assessment

The most important role of coronary angiography is to delineate coronary lesions that cause inducible ischaemia. It remains the primary tool influencing the decision to undertake revas‐ cularization and patient outcomes [1] [2-4]. However, there are inherent limitations to diag‐ nostic angiography. These pitfalls include difficulties delineating eccentric plaque (that can be underappreciated in the absence of multiple angiographic views), difficulty assessing le‐ sions of moderate severity, the assessment of overall plaque burden and the composition, appreciation of ostial lesions, culprit lesion assessment in acute infarct patients and side branch analysis in bifurcation lesions. Heavily calcified lesions can also produce hazy angio‐ graphic appearances which often leaves the operator at a loss to determine the actual true lumen path and in some circumstances even misdiagnose calcification as “pseudothrom‐ bus” [5]. This latter phenomenon significantly changes the approach to intervention. The ar‐ tery can be put at risk of perforation in the absence of adequate lesion preparation or wire induced dissection as calcified plaque is often undermined, complex and much more diffi‐ cult to wire than soft thrombus.