[Direct thrombin inhibitors in coronary angioplasty. Value of bivalirudin ]

During coronary angioplasty, the association of platelet inhibitors and antithrombin agents is required to prevent myocardial infarction. Bivalirudine, a synthetic direct thrombin inhibitor, has been widely validated in this context and has shown its efficacy and safety in several comparative studies. It is officially recommended as a replacement of NFH and LMWH associated or not with anti-GPIIb/IIIa agents because at comparable efficacy it causes fewer bleeding complications. In acute coronary syndromes without ST elevation, anti GPIIb/IIIa agents reduce angioplasty-related complications and mortality, especially in high risk patients in salvage situations. In the REPLACE-2 trial the clinical efficacy of bivalirudine (associated only when necessary with anti-GPIIb/IIIa agents) was no less than that of NFH associated systematically with anti-GPIIb/IIIa agents at the time of intervention. The incidents of serious adverse events at 30 days (death, infarctus, emergency revascularisation, major bleeding) in the bivalirudine group was 9.2% versus 10.2% in the NFH group. In a retrospective analysis, these results did not seem to be influenced by the prior administration of clopidogrel. Finally, the one year follow-up results showed a lower mortality in patients treated with bivalirudine (1.9% versus 2.5%), essentially in the high risk sub-groups such as the elderly, the diabetic or the renal failure patients. Clinical trials are underway (ACUITY) to study the interaction of anti GPIIb/IIIa agents with bivalirudine in the first hours of acute coronary syndromes and should confirm a major role of direct anti-thrombin drugs in the safety of angioplasty.

[Fibrinolysis in myocardial infarction with EKG elevation. Optimization of myocardial reperfusion by treatment with antithrombotic agents]

In the case of acute coronary syndrome with prolonged ST elevation on ECG showing an acute coronary obstruction, the urgent institution of fibrinolysis is a widely validated treatment. Since the first placebo controlled studies with streptokinase until the development of bolus administration rt-PA varieties, fibrinolytic agents have lowered mortality. Associated anti-thrombotic drugs are multiplying in parallel. Their association is recognised as necessary in order to avoid early reocclusions which worsen the prognosis of infarction, the fibrinolysis triggering a harmful prothrombotic effect, notably due to the clot thrombin re-exposed during thrombolysis. Aspirin has an essential place formally demonstrated in ISIS 2. Non-fractionated heparin has more complex effects and its administration protocol in association with fibrinolysis has recently been reviewed with a reduction in dosage because prolonged clotting times during fibrinolysis have provoked a distinct increase in the risk of intracranial haemorrhage. The low molecular weight heparins seem to have become the adjuvant treatment of choice following publication of the ASSENT-3 trial. Pentasaccharide seems attractive. The place of hirudine and its derivatives in the acute phase of MI appear limited after the results of the HERO-2 trial, associating hirulog and streptokinase, with the earlier studies also having been disappointing. The GPIIbIIIa blockers in association with a half dose of fibrinolysis do not aggravate the intracerebral haemorrhagic risk before 75 years old and clearly reduce hospital morbidity in infarction, at the price however of an increase in transfusions.

[Anticoagulation in mechanical valve prostheses. A difficult situation]

Although long-term anticoagulant therapy in patients with mechanical valve prostheses is well codified, a number of difficult situations persists because of the high thromboembolic risk. The protocols of anticoagulation suggested in these situations are controversial as there are no large scale prospective therapeutic trials. However, modern protocols take more and more into account the thromboembolic risk in each individual case. The authors review the most common situations: the early postoperative period for which no precise consensus exists in the literature; anticoagulation in extra-cardiac surgery, a common situation for which the protocols remain very debatable; anticoagulation in pregnancy, a special situation because of the risk of embryopathy with oral anticoagulant therapy and the risk of thromboembolism with heparin; anticoagulation in cases of thromboembolic complications; anticoagulation during infectious endocarditis; anticoagulation during serious haemorrhage.

[Treatment of left atrial thrombosis by low-molecular-weight heparin. A preliminary study of 6 cases]

Left atrial thrombosis is a serious complication of atrial fibrillation because of its embolic potential, especially for the cerebral circulation. These thrombi are usually treated by oral anticoagulation. The authors studied the efficacy and tolerance of a low molecular weight heparin. Enoxaparin, in the treatment of this condition. This was a prospective study carried out over a 1 year period. Patient recruitment came from the transoesophageal echocardiography laboratory: of 15 thrombi detected, 6 were treated by ambulatory Enoxaparin therapy. Five of the 6 patients had no signs of left atrial thrombosis after 3 weeks of Enoxaparin therapy. The left atrial thrombus of the 6th patient remained hyperechogenic and had decreased in length from 27 to 24 mm. No cases of bleeding, haematoma, embolism or thrombopenia were observed with this treatment. This preliminary study shows that low molecular weight heparin may be used as an alternative to classical oral anticoagulation for the treatment of left atrial thrombosis.

[Local progression of atherosclerosis after optimal directional atherectomy. Endocoronary ultrasonography of 17 patients]

In vivo endovascular ultrasonography has confirmed the extension of atheroma to angiographically normal segments. The authors set out to determine by endocoronary ultrasonography if the introduction of the atherotome changed the intimal thickness 20 mm proximal and distal to the site treated. The area circumscribed by the external elastic layer (EEL) and the surface area of the lumen was measured in 17 patients: 1) before atherectomy; 2) after atherectomy; 3) at control 6 months later. Atherectomy immediately increased the luminal area at the site dilated from 1.9 + 0.9 to 8.1 +/- 2mm (p < 0.001). At the proximal segment, the surface area of the lumen was unchanged (mean + 0.6 +/- 1.5 mm2; p = 0.13). Similarly the procedure did not change the surface circumscribed by the EEL (mean + 0.8 +/- 3.2 mm2; p = 0.32) in this zone. The same results were observed at the distal site. At 6 months, the areas under the EEL and those of the lumen were unchanged at the unoperated sites. The mean of the differences (+/- 1 SD) for the area under the EEL was respectively -0.2 +/- 1.5 mm2 proximally and +0.7 +/- 2.5 mm2 distally. The means for the luminal area were 0.2 +/- 1 mm2 proximally and -0.01 +/- 1.1 mm2; distally. At the site of atherectomy, the luminal surface increased (+2.0 +/- 2.6 mm2; p < 0.01) as did the area under the EEL (+2.0 +/- 3.5 mm2; p < 0.05). This preliminary series shows no significant progression of atherosclerosis at the sites not affected by atherectomy.

[Restenosis after optimal coronary atherectomy and influence on left ventricular function]

The authors prospectively assessed 95 patients undergoing optimal guided atherectomy to assess the incidence of restenosis at 6 months. The coronary lesions were measured by a system of quantitative angiography to ensure reproducibility. Ventricular volumes, ejection fraction and segmental wall motion were assessed by ventriculography performed in the right anterior oblique projection. Sixty-three patients underwent atherectomy of the left anterior descending artery and 32 patients of the right coronary artery. The reference diameter was 3.58 +/- 0.65 mm. Atherectomy increased the minimal diameter of the lesion from 1.19 +/- 0.44 to 3.03 +/- 0.45 mm, with a residual stenosis of 14 +/- 10% of the diameter. At 6 months, 23% of patients had restenosed (> 50% stenosis) with a residual lumen at 1.16 +/- 0.39 mm. In the absence of restenosis, there was no significant change in left ventricular volumes or pressures and the global ejection fraction increased by +4 +/- 9% (p < 0.01), mainly in the group undergoing left anterior descending atherectomy. Moreover, fractional shortening increased in the anterior segments (+11 +/- 18%; p < 0.001). The authors conclude that optimal atherectomy is associated with acceptable rates of restenosis and that medium-term benefits of segmental wall motion are observed in patients without angiographic restenosis, mainly in those undergoing the procedure on the left anterior descending artery.

Impact of restenosis after optimal directional coronary atherectomy on regional left ventricular function

To assess the effect of optimal directional coronary atherectomy (DCA) on restenosis and left ventricular (LV) function, 95 patients who underwent DCA and adjunctive balloon angioplasty for de novo lesions were prospectively followed for 6 months. Absolute and relative coronary lumen measurements were analyzed with online quantitative coronary angiography. LV volumes, ejection fraction, and segmental wall motion were measured off-line according to the radial method for LV cineangiograms acquired in a right anterior oblique projection. Target vessels were the left anterior descending artery in 63 patients and right coronary artery in 32. Mean (+/- SD) reference diameter was 3.58 +/- 0.65 mm. Mean lumen diameter improved significantly after DCA from 1.19 +/- 0.44 to 3.03 +/- 0.45 mm, yielding a 14 +/- 10% residual stenosis. Overall angiographic restenosis rate (> 50% stenosis in diameter) at control was 23%. In patients without restenosis, there were no significant changes in LV volumes or in LV pressures. In this subgroup, ejection fraction improved significantly in the left anterior descending group (mean difference 3 +/- 10%, p < 0.04). Moreover, there was an increase in fractional shortening of all anterior segments (mean difference 11 +/- 16%, p < 0.005). Improvement in fractional shortening was less marked in the right coronary artery group even without restenosis. We conclude that: (1) optimal DCA can achieve a low restenosis rate in selected large vessels, (2) long-term beneficial effects on regional LV function are possible, particularly in patients with left anterior descending disease and in the absence of coronary restenosis.

[Predictive factors of coronary restenosis after optimal directional atherectomy. A multivariate analysis apropos of 102 patients]

The authors studied 102 patients prospectively who were undergoing coronary atherectomy optimised by balloon dilatation in order to assess the restenosis rate at 6 months. The coronary lesions were measured in a reproducible manner by quantitative angiography. The vessels dilated were the left anterior descending in 66 patients and the right coronary artery in 36 patients. The reference diameter was on average of 3.57 +/- 0.64 mm. Atherectomy increased the minimal diameter of the lesion of 1.20 +/- 0.44 to 3.01 +/- 0.44 mm giving a residual stenosis of 15 +/- 11%. At six months, 25% of patients had developed a restenosis (> 50% stenosis) with a residual lumen of 2.15 +/- 0.77 mm. The predictive factors of restenosis were the initial absolute gain, the length of the lesion, the reference diameter of the vessel and the presence of an endoluminal thrombus. In multivariate analysis, a small initial gain (p < 0.02) and length of stenosis (p < 0.02) were independently correlated with restenosis. The authors conclude: 1) that optimal atherectomy is associated with acceptable restenosis rates in selected vessels, 2) that short stenoses of large diameter arteries may be a privileged indication of the technique if the best results are obtained.