Transient thrombotic state after abrupt discontinuation of heparin in percutaneous coronary angioplasty

A pilot study documenting increased thrombin generation following abrupt withdrawal of heparin therapy in healthy dogs

OBJECTIVE

To document if a transient hypercoagulable state occurs in healthy dogs following abrupt cessation of unfractionated heparin (UFH) therapy.

DESIGN

Prospective experimental pilot study.

SETTING

University research facility.

ANIMALS

Seven adult random-source male dogs.

INTERVENTION

Thromboelastography (TEG) and thrombin-antithrombin (TAT) complex formation were used to assess coagulation status in healthy dogs. Seven adult research dogs received 200-300 IU/kg subcutaneous UFH every 8 hours for 4 days. A final IV bolus of 100 IU/kg was given on day 4 and the peak measured heparin concentration 1 hour later is defined as the start of heparin withdrawal (time 0). Citrated whole blood samples were collected at baseline (prior to heparin administration) and 3, 6, 12, 30, and 48 hours after UFH withdrawal. At all time points, a kaolin-activated TEG was performed and citrated plasma for measurement of TAT concentration was collected for batch analysis. Fibrinogen concentration, PCV, total plasma proteins, and platelet count were measured at baseline and 48 hours after heparin withdrawal.

MEASUREMENTS AND MAIN RESULTS

Compared to baseline, TAT was increased 12 hours after heparin withdrawal and returned to baseline by 30 hours. TEG clot formation time (K) was decreased 30 and 48 hours after heparin withdrawal.

CONCLUSION

TAT results suggest that a transient increase in thrombin generation developed 12 hours after withdrawal of UFH therapy. Though clot kinetics were rapid compared to baseline beginning 30 hours after heparin withdrawal, a return to baseline was not documented. Future studies are warranted to determine the clinical relevance of these results and to evaluate the effect of UFH withdrawal in critically ill animals.

Controlled continuous systemic heparinization increases success rate of artery-only anastomosis replantation in single distal digit amputation: A retrospective cohort study

Replantation is a prime indication for distal digital amputation, as it helps restore hand aesthetics and functions; however, venous anastomosis is often not feasible. Previous studies used systemic anticoagulation in distal digital artery only anastomosis replantation surgery to improve replantation success rate, however, which yielded limited level of clinical evidence. This study aimed to compare controlled continuous heparinization (CCH) and intermittent bolus heparinization (IBH) for surgical outcome and clinical variables after single distal digital artery only anastomosis replantation surgery.A single-institution, retrospective cohort study was performed. Out of 324 patients who underwent digital replantation surgery, we focused the study for the Zone I and II single distal digital amputation patients excluding confounding factors. Sixty-one patients were included in this study and underwent artery-only anastomosis replantation surgery with postoperative CCH (34 patients) or IBH (27 patients) protocols. The CCH group targeted activated partial thromboplastin time (aPTT) at 51 to 70 seconds, monitoring aPTT levels every eight hours and administering 100 mg of aspirin per day. The IBH group received 300 mg of aspirin per day and underwent IBH (12,500 U). Both groups received intravenous prostaglandin E1 drips (10 μg). To verify the factors affecting the success rate of the heparin protocol, patient factors, clinical factors, and operative factors were extracted from the medical records. Statistical analysis with inverse probability of treatment weights propensity score methods compared treatment outcomes and clinical variables.The CCH group's replantation success rate was higher (91.17% vs 59.25%), and the transfusion rate was increased (P = 0.032). However, the significant decrease in hemoglobin levels (>15%) did not differ between the groups (P = 0.108). Multivariable logistic regression analysis with potent univariate variables (P < .10) revealed that CCH was a statistically significant variable in replantation success rate (P = 0.004). Neither the major bleeding complications nor the significant decrease in patients' platelet levels were observed in both groups.Our study suggests that CCH after artery-only anastomosis replantation surgery in Zone I and II distal digital replantation is a safe method to improve the replantation success rate and may provide a guideline for use of the anticoagulation method following artery-only anastomosis distal digital replantation surgery.

Effectiveness and safety of reduced-dose enoxaparin in non-ST-segment elevation acute coronary syndrome followed by antiplatelet therapy alone for percutaneous coronary intervention

Adjunctive pharmacotherapy for stabilizing patients with acute coronary syndrome/non-ST-segment elevation myocardial infarction (ACS/NSTEMI) and for subsequent percutaneous coronary intervention (PCI) includes a combination of anticoagulant and antiplatelet agents. However, all anticoagulants have been shown to paradoxically activate platelets and induce other prothrombotic activities, increase bleeding, and/or cause thrombocytopenia. A single-center experience of 1,400 consecutive patients presenting with ACS/NSTEMI managed using decreased-dose anticoagulation (enoxaparin) and dual-antiplatelet therapy (aspirin and clopidogrel) followed by triple-antiplatelet therapy (aspirin, clopidogrel, and eptifibatide) alone, without additional anticoagulation, during subsequent PCI was retrospectively analyzed. Patients received a median of 3 doses of enoxaparin at a mean dose of 0.51 mg/kg. The final dose was administered 10.8 hours (mean) before PCI. Medical management "failed" in 8 patients (0.6%), and each required emergency PCI. The overall technical success rate was 99.8%. One major adverse clinical event (0.1%) occurred within 24 hours after PCI. Non-Q-wave myocardial infarction occurred in 1.8% of patients, major and minor bleeding complications, in 0.1% and 2.1%, respectively, and thrombocytopenia in 1.3%. Five additional major adverse clinical events (0.4%) occurred within 30 days after PCI, none involving target vessel thrombosis. In conclusion, for patients with ACS/NSTEMI, reduced-dose enoxaparin combined with dual-antiplatelet therapy followed by triple-antiplatelet therapy alone (without additional anticoagulation) during subsequent PCI appears safe and may prove efficacious.

Effect of the novel direct factor Xa inhibitor DX-9065a on thrombin generation and inhibition among patients with stable atherosclerotic coronary artery disease

INTRODUCTION

Thrombin, a pluripotential effector enzyme with prothrombotic, proinflammatory, and mitogenic properties, plays a pivotal role in the pathobiology and clinical expression of atherothrombotic coronary artery disease. Existing anticoagulant drugs have not been shown to attenuate thrombin generation or activity consistently. We sought to investigate the effect of DX-9065a on thrombin generation and inhibition in patients with stable CAD. DX-9065a is a small-molecule, synthetic, direct inhibitor of factor Xa.

MATERIALS AND METHODS

Peripheral venous blood samples were collected serially during and after administration of either placebo or 1 of 4 weight-adjusted regimens of DX-9065a, in 73 patients with stable CAD participating in the XaNADU-1B study.

RESULTS AND CONCLUSIONS

At baseline, the median (25th, 75th) prothrombin activation fragment 1.2 (F1.2) level was 2.56 (2.05, 3.20) nmol/L, and the median d-dimer level was 0.26 (0.19, 0.38) microg FEU/L. There were significant relationships between measured plasma DX-9065a concentrations and both F1.2 (4.9% decrease for each doubling of DX-9065a) (P<0.0001) and d-dimer (5.5% decrease for each doubling of DX-9065a) (P=0.001). F1.2 was suppressed (below baseline) at 96 h after administration of DX-9065a. Coronary thrombotic events did not occur during or after study drug administration. DX-9065a, the first in a class of small-molecule, direct, selective and reversible factor Xa inhibitors, reduces thrombin generation and fibrin formation among patients with stable CAD. The effect is concentration-dependent and persists for at least 96 h following drug cessation, without biochemical or clinical evidence of rebound.

Elective percutaneous coronary intervention using broad-spectrum antiplatelet therapy (eptifibatide, clopidogrel, and aspirin) alone, without scheduled unfractionated heparin or other antithrombin therapy

BACKGROUND

Adjunctive pharmacotherapy during percutaneous coronary intervention (PCI) has historically consisted of a regimen of antiplatelet agents accompanied by an antithrombin agent, typically unfractionated heparin. Paradoxically, unfractionated heparin may activate platelets, induce other pro-thrombotic activities, increase bleeding complications, and cause thrombocytopenia. To optimize patient care and avoid the potential risks of unfractionated heparin in patients undergoing elective PCI, one of the authors began to use adjunctive pharmacotherapy consisting of broad-spectrum antiplatelet therapy alone, without scheduled unfractionated heparin or other antithrombin therapy.

METHODS

Five hundred consecutive patients undergoing scheduled, elective PCI (stent deployment, cutting balloon atherotomy, conventional balloon angioplasty, or high-speed rotational atherectomy) received adjunctive pharmacotherapy consisting of eptifibatide, clopidogrel, and aspirin.

RESULTS

The technical success rate was 100%. During the first 24 hours, there were no major adverse clinical events. Non-Q-wave myocardial infarction occurred in 1.6% of patients, major and minor bleeding complications in 0.2% and 0.6%, respectively, and thrombocytopenia in 0.6%. During the first 30 days, there was 1 (0.2%) major adverse clinical event.

CONCLUSIONS

For elective PCI, adjunctive pharmacotherapy consisting of broad-spectrum antiplatelet therapy alone, without scheduled unfractionated heparin or other antithrombin therapy, appears to be safe and may prove to be efficacious.

Hemostatic and fibrinolytic activation is less following cutting balloon angioplasty of the coronary arteries

Recent studies have shown that percutaneous coronary intervention (PCI) activates systemic hemostatic activity, reflecting platelet activation and thrombin formation in the coronary arteries. The present study compared systemic levels of hemostatic markers induced by plain old balloon angioplasty (POBA), coronary stenting (STENT), and cutting balloon (CB) angioplasty. Sixty-one patients with stable angina pectoris, who underwent elective PCI or diagnostic coronary angiography (CAG) alone, were investigated. Patients who underwent PCI were divided into the POBA group (n = 11), the STENT group (n = 27), and the CB group (n = 11). Patients who underwent CAG alone were assigned to the CAG group (n = 12). Blood samples were collected before, 24 hours after, and 3 days after PCI or CAG. Plasma concentrations of prothrombin fragment 1+2 (F1+2), fibrinopeptide A (FPA), thrombin-antithrombin III complex (TAT), and plasminogen activator inhibitor-1 (PAI-1) were measured. In the CB group, the F1+2 (1.23 +/- 0.4 nmol/L) level 3 days after PCI was significantly smaller than that of the POBA group (2.37 +/- 0.5 nmol/L) (P < 0.05). The FPA (1.81 +/- 0.9 ng/mL), TAT (3.36 +/- 1.2 ng/mL) and PAI-1 (23.0 +/- 4.1 ng/mL) levels in the CB group 3 days after PCI were significantly smaller than those of the POBA group (P < 0.05, respectively) and STENT group (P < 0.05, respectively), but similar to the CAG group. Systemic hemostasis is activated to a greater extent after POBA and stenting than it is after CB angioplasty of the coronary arteries. This may contribute to the favorable long-term outcome of CB angioplasty.

Acenocoumarol associated priapism: report of a case

We report on a 20-year-old man presenting with priapism while receiving oral acenocoumarol for the treatment of deep vein thrombosis. To the authors' knowledge, it is the first reported case of acenocoumarol-associated priapism.

Efficacy and safety of minimal dose (< or =1,000 units) unfractionated heparin with abciximab in percutaneous coronary intervention

Abciximab decreases adverse cardiac ischemic events, and in some subgroups, decreases the need for revascularization after percutaneous coronary intervention (PCI). However, abciximab may cause bleeding complications and thrombocytopenia after PCI. We hypothesized that the efficacy and safety of PCI would be maintained, if not improved, when performed using abciximab accompanied by only minimal doses (< or =1,000 U) of unfractionated heparin. In this prospectively designed observational study, we assessed 500 consecutive patients who underwent PCI, consisting of either stent deployment or high-speed rotational atherectomy, and who received abciximab accompanied by only a minimal dose of unfractionated heparin, as directed by a novel dosing strategy: (1) if the patient was previously receiving an infusion of heparin, then it was terminated upon arrival to the cardiac catheterization laboratory, and no further heparin was administered; or (2) if the patient was not receiving an infusion of heparin, then a single bolus infusion of 1,000 U was administered after establishment of vascular access. The median activated clotting time for the patients during PCI was 168 seconds (25% quartiles, 153 to 185). The technical success rate was 99.8%. There were no major adverse clinical events during the 24 hours after PCI. The incidence of non-Q-wave myocardial infarction was 1.6%. The incidences of major and minor bleeding complications were 0.2% and 3.6%, respectively, and the incidence of thrombocytopenia was 2.2%. During the 30 days after PCI, there was 1 major adverse clinical event (0.2%). During the 1 year after PCI, among the remaining patients, there were 92 adverse events (18.4%). We conclude that, in the context of historical data, the efficacy and safety of PCI using either stent deployment or high-speed rotational atherectomy is maintained, if not improved, when performed using abciximab accompanied by only minimal doses of unfractionated heparin.

Argatroban: a direct thrombin inhibitor for heparin-induced thrombocytopenia and other clinical applications

Argatroban, a direct thrombin inhibitor derived from arginine, is an effective anticoagulant indicated for prophylaxis or treatment of thrombosis in patients with heparin-induced thrombocytopenia (HIT). Argatroban has been used as an alternative anticoagulant in patients with HIT in various clinical conditions including interventional cardiovascular procedures that require anticoagulation. Satisfactory clinical outcomes with acceptable complications have been reported in these patients. Whether argatroban offers additional clinical advantage over conventional heparin therapy in patients without HIT remains unclear. Argatroban has been evaluated as an alternative anticoagulant to replace heparin in various clinical studies, especially in patients with coronary artery disease or cerebral vascular disease. To date, it remains unclear if argatroban is more effective than heparin, although the agent seems to cause less bleeding complications. This article reviews the pharmacology of argatroban and its clinical application beyond the management of HIT, with particular emphasis on interventional cardiology procedure, acute myocardial infarction, unstable angina pectoris, cerebral thrombosis or ischemic stroke, peripheral obstructive arterial disease, and extracorporeal circulation.

Usefulness of intravenous enoxaparin for percutaneous coronary intervention in stable angina pectoris

This pilot study was designed to determine whether the low molecular weight heparin, enoxaparin, could be used for elective percutaneous coronary intervention (PCI) to provide antithrombotic effects without the full systemic anticoagulation that occurs with the use of unfractionated heparin. Sixty patients were randomized to receive intravenous enoxaparin (1 mg/kg bolus dose) or unfractionated heparin at the time of coronary intervention. Laboratory testing was performed at baseline, 5 minutes, and 4 hours after study drug to test if a single bolus dose of intravenous enoxaparin can consistently achieve therapeutic antithrombotic effect, thus eliminating the need for multiple doses of heparin and closely monitoring levels of anticoagulation during PCI. Thirty percent of patients who received unfractionated heparin required a second bolus of intravenous heparin to achieve the target-activated clotting time of 300 seconds before PCI. Enoxaparin showed antithrombotic properties comparable to that of unfractionated heparin as measured by anti-Xa levels, with less inhibition of thrombin (factor IIa) at the time points measured (p <0.0001). Angioplasty success rates, in-hospital ischemia, bleeding, and vascular complications were similar in both groups. Thus, intravenous enoxaparin has predictable and effective antithrombotic effects during elective PCI. Although the level of anticoagulation attained with enoxaparin is significantly lower than that after unfractionated heparin, no increase in ischemic complications were noted. The use of a single bolus of intravenous enoxaparin, without the need for measuring the activated clotting time or titrating heparin anticoagulation, has the potential for simplifying the performance and perhaps enhancing the safety of PCI.

Thrombin generation after the abrupt cessation of intravenous unfractionated heparin among patients with acute coronary syndromes: potential mechanisms for heightened prothrombotic potential

OBJECTIVES

The purpose of this study was to determine the mechanistic basis for thrombin generation and increased prothrombotic potential after the abrupt cessation of intravenous (i.v.) unfractionated heparin among patients with acute coronary syndromes.

BACKGROUND

A "rebound" increase in prothrombotic potential has been observed biochemically and clinically after the abrupt cessation of unfractionated heparin (UFH) among patients with acute coronary syndromes. Although the mechanism is unknown, tissue factor and the extrinsic coagulation cascade, both operative in atherosclerotic vascular disease and arterial thrombosis, are thought to be centrally involved.

METHODS

In a single-center, pilot study, 30 patients with either unstable angina or non-ST segment elevation myocardial infarction who had received a continuous i.v. infusion of UFH for 48 h were randomly assigned to: 1) abrupt cessation, 2) i.v. weaning over 12 h or 3) subcutaneous weaning over 12 h.

RESULTS

Thrombin generation (prothrombin fragment 1.2) was evident within 1 h of UFH cessation, increased progressively (by nearly two-fold) at 24 h (p = 0.002) and correlated inversely with tissue factor pathway inhibitor concentration (r = -0.61). Thrombin generation was greatest among patients randomized to abrupt cessation (1.6-fold increase at 24 h) and least in those with i.v. weaning.

CONCLUSIONS

Thrombin generation after the abrupt cessation of UFH may represent a drug-induced impairment of physiologic vascular thromboresistance in response to locally generated tissue factor. A dosing strategy of abbreviated i.v. weaning attenuates but does not prevent heparin rebound among patients with acute coronary syndromes.

Oral blockade of the platelet glycoprotein IIb/IIIa receptor: fact or fancy?

Currently available antiplatelet agents are limited in the scope and magnitude of platelet inhibition. Orally active platelet glycoprotein IIb/IIIa antagonists are currently in clinical testing. These agents may extend platelet inhibition and clinical benefit from parenteral glycoprotein IIb/IIIa antagonists. The most common adverse side effect is mucocutaneous bleeding, which is related to the magnitude and duration of platelet inhibition. Point-of-care monitoring of platelet function may enhance safety and efficacy of oral platelet GP IIb/IIIa blockade. Because aspirin, ticlopidine, and clopidogrel have proved beneficial in reducing vascular ischemic events, oral platelet glycoprotein IIb/IIIa inhibitors, which provide more marked platelet inhibition, are positioned to provide even greater clinical benefit if tolerated.

Failure of early heparin cessation as treatment for heparin-induced thrombocytopenia

PURPOSE

The complications of heparin-induced thrombocytopenia include thrombosis and death. The purpose of the study was to determine whether early heparin cessation can prevent these outcomes.

SUBJECTS AND METHODS

We performed a retrospective analysis of consecutive patients with heparin-induced thrombocytopenia diagnosed by platelet aggregometry. Demographic, clinical, and laboratory findings were compared in patients by whether heparin treatment was stopped early (< or = 48 hours) or late (>48 hours) after the onset of thrombocytopenia, as well as between patients with and without thrombosis. Thrombocytopenia was defined as a 50% decline in baseline platelet counts or an absolute platelet count < 100,000/mm3.

RESULTS

Of the 113 patients, 38% developed thrombosis and 27% died. One-half of patients had thrombosis diagnosed >24 hours after heparin cessation. No difference in thrombosis or mortality was found in the 40 patients with early heparin cessation [mean (+/-SD) time of cessation 0.7 +/- 0.6 days] compared with the 73 patients with late heparin cessation (5 +/- 3 days). Thrombosis >24 hours after heparin cessation occurred in 61% of the patients in the early group and in 40% of the late group (P = 0.17). In a multivariate analysis, only a lower nadir of the platelet count (percent of baseline) was associated with thrombosis. Neither thrombosis nor the time to heparin cessation were associated with mortality.

CONCLUSIONS

Early heparin cessation was not effective in reducing morbid events in patients with heparin-induced thrombocytopenia. Treatment strategies other than heparin cessation alone should be considered in patients with this condition.

Antithrombin activity during the period of percutaneous coronary revascularization: relation to heparin use, thrombotic complications and restenosis

OBJECTIVES

This study evaluated changes in antithrombin (AT) activity around the time of percutaneous transluminal coronary revascularization (PTCR) with unfractionated heparin anticoagulation and the effects these changes had on major thrombotic complications of PTCR.

BACKGROUND

Heparin is used during PTCR to prevent thrombosis. However, heparin, a cofactor for AT, causes AT activity to fall. AT activity <70% is associated with thrombosis. There is a prothrombotic state after heparin discontinuation that has not been well explained.

METHODS

Antithrombin activity was sampled at the start and end of PTCR and the next two mornings in 250 consecutive patients. We recorded occurrence of major thrombotic events, defined as 1) major thrombotic complications of PTCR; 2) major in-lab thrombus formation; or 3) subacute occlusion. Discriminant analysis was employed to evaluate the relationship of AT activity to these events. Change in AT activity and its relationship to heparin was evaluated. Evidence of restenosis at six months was obtained.

RESULTS

There were 14 major thrombotic events. Antithrombin activity <70% was strongly (p = 0.006) associated with these events. The AT activity fell significantly through the morning after PTCR when 21% of patients had AT activity <70%; AT activity did not normalize until >20 h after heparin discontinuation. Pre-PTCR use of heparin led to lower AT activity in proportion to duration of heparin use. There was no relationship between AT activity and restenosis.

CONCLUSIONS

Low AT activity may contribute to major thrombotic complications of PTCR. The way heparin is used before and after PTCR is important to development of low AT activity.

Clinical and angiographic follow-Up after primary stenting in acute myocardial infarction: the Primary Angioplasty in Myocardial Infarction (PAMI) stent pilot trial

BACKGROUND

Restenosis has been reported in as many as 50% of patients within 6 months after PTCA in acute myocardial infarction (AMI), which necessitates repeat target-vessel revascularization (TVR) in approximately 20% of patients during this time period. Routine (primary) stent implantation after PTCA has the potential to further improve late outcomes.

METHODS AND RESULTS

Primary stenting was performed as part of a prospective study in 236 consecutive patients without contraindications who presented with AMI of <12 hours' duration at 9 international centers. A mean of 1.4+/-0.7 stents were implanted per patient (97% Palmaz-Schatz) at 17.3+/-2.4 atm. During a clinical follow-up period of 7.4+/-2.6 months, death occurred in 4 patients (1.7%), reinfarction occurred in 5 patients (2.1%), and TVR was required in 26 patients (11.1%). By Cox regression analysis, small reference-vessel diameter and the number of stents implanted were the strongest determinants of TVR. Angiographic restenosis occurred in 27.5% of lesions. By multiple logistic regression analysis, the number of stents implanted and the absence of thrombus on the baseline angiogram were independent determinants of binary restenosis.

CONCLUSIONS

A strategy of routine stent implantation during mechanical reperfusion of AMI is safe and is associated with favorable event-free survival and low rates of restenosis compared with primary PTCA alone.

Case studies in therapeutics: warfarin resistance and inefficacy in a man with recurrent thromboembolism, and anticoagulant-associated priapism

Case report

A 52 year-old male unemployed labourer was referred because of recurrent thromboembolism. An episode of thrombophlebitis migrans 3 months earlier had been followed by a pulmonary embolus a week later, and then a deep vein thrombosis despite apparently adequate anticoagulant therapy with warfarin 10 mg daily (INRs between 2 and 4). For 9 years he had suffered from hypertension for which he took lisinopril 2.5 mg daily, had smoked 20 cigarettes daily since his teens and drank 12–15 pints of beer each week. On presentation, his right leg remained hot, swollen and tender to the thigh but there were no other abnormal findings. Investigations revealed a normochromic, normocytic anaemia (Hb 11.6 g dl⁻¹ ) and his erythrocyte sedimentation rate, which had been 11 mm h⁻¹, had risen to 35 mm h⁻¹. Renal and liver function tests, autoantibody screen, and prostate-specific antigen were normal. Antithrombin III, protein C and S concentrations were all within normal limits and ultrasound of the abdomen and pelvis, barium meal and enema, and CT of the thorax, abdomen and pelvis, bronchoscopy and brushings also failed to reveal any abnormality.

He was commenced on full-dose (porcine mucosal) heparin for 10 days and the warfarin dose was increased to 15 mg daily until his INR had risen to 4.0, when his plasma warfarin concentration was measured at 3.1 mg l⁻¹.

Prolonged heparin after uncomplicated coronary interventions: a prospective, randomized trial

BACKGROUND

Continuous heparin infusion after percutaneous transluminal coronary angioplasty (PTCA) procedures prolongs the hospital stay and could increase the occurrence of bleeding complications. The aim of this randomized trial was to evaluate whether omission of heparin infusion after uncomplicated coronary interventions in patients with stable and unstable angina with or without stent implantation increased the incidence of acute cardiac complications.

METHODS AND RESULTS

A total of 191 consecutive patients who underwent successful PTCA were randomly assigned to receive either prolonged heparin (heparin group) or no postprocedure heparin (control group). The 2 treatment groups were comparable with respect to clinical and angiographic characteristics. Stents were used in 36% of the control group and in 33% of the heparin group. Cardiac complications occurred in 8 (4%) patients. Four (4%) patients in the control group and 3 (3%) patients in the heparin group had a myocardial infarction. One patient in the control group died 3 days after the intervention. No patient in either group needed a repeat revascularization during the target hospitalization. Peripheral vascular complications in the control and heparin groups occurred in 1% and 3% of the patients, respectively.

CONCLUSIONS

Omission of heparin after successful PTCA with or without stent implantation in patients with stable and unstable angina did not significantly increase the incidence of acute cardiac complications. It allows for early sheath removal and patient discharge and saves costs. This study, combined with other small studies in the field, provides strong evidence that heparin should not be used routinely.

Prospective, multicenter study of the safety and feasibility of primary stenting in acute myocardial infarction: in-hospital and 30-day results of the PAMI stent pilot trial. Primary Angioplasty in Myocardial Infarction Stent Pilot Trial Investigators

OBJECTIVES

The goals of this study were to examine the safety and feasibility of a routine (primary) stent strategy in acute myocardial infarction (AMI).

BACKGROUND

Limitations of reperfusion by primary percutaneous transluminal coronary angioplasty (PTCA) in AMI include in-hospital recurrent ischemia or reinfarction in 10% to 15% of patients, restenosis in 37% to 49% and late infarct-related artery reocclusion in 9% to 14%. By lowering the residual stenosis and sealing dissection planes created by PTCA, primary stenting may further improve short- and long-term outcomes after mechanical reperfusion.

METHODS

Three hundred twelve consecutive patients treated with primary PTCA for AMI at nine international centers were prospectively enrolled. After PTCA, stenting was attempted in all eligible lesions (vessel size 3.0 to 4.0 mm; lesion length < or = 2 stents; and the absence of giant thrombus burden after PTCA, major side branch jeopardy or excessive proximal tortuosity or calcification). Patients with stents were treated with aspirin, ticlopidine and a 60-h tapering heparin regimen.

RESULTS

Stenting was attempted in 240 (77%) of 312 patients, successfully in 236 (98%), with Thrombolysis in Myocardial Infarction grade 3 flow restored in 230 patients (96%). Patients with stents had low rates of in-hospital death (0.8%), reinfarction (1.7%), recurrent ischemia (3.8%) and predischarge target vessel revascularization for ischemia (1.3%). At 30-day follow-up, no additional deaths or reinfarctions occurred among patients with stents, and target vessel revascularization was required in only one additional patient (0.4%).

CONCLUSIONS

Primary stenting is safe and feasible in the majority of patients with AMI and results in excellent short-term outcomes.

A prospective, randomized evaluation of prophylactic intraaortic balloon counterpulsation in high risk patients with acute myocardial infarction treated with primary angioplasty. Second Primary Angioplasty in Myocardial Infarction (PAMI-II) Trial Investigators

OBJECTIVES

A large, international, multicenter, prospective, randomized trial was performed to determine the role of prophylactic intraaortic balloon pump (IABP) counterpulsation after primary percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (AMI).

BACKGROUND

Previous studies have suggested that routine IABP use after primary PTCA reduces infarct-related artery reocclusion, augments myocardial recovery and improves clinical outcomes.

METHODS

Cardiac catheterization was performed in 1,100 patients within 12 h of onset of AMI at 34 clinical centers. Clinical and angiographic variables were used to stratify patients undergoing primary PTCA into high and low risk groups. High risk patients were then randomized to 36 to 48 h of IABP (n = 211) or traditional care (n = 226). The study had 80% power to detect a reduction in the primary end point from 30% to 20%.

RESULTS

There was no significant difference in the predefined primary combined end point of death, reinfarction, infarct-related artery reocclusion, stroke or new-onset heart failure or sustained hypotension in patients treated with an IABP versus those treated conservatively (28.9% vs. 29.2%, p = 0.95). The IABP strategy conferred modest benefits in reduction of recurrent ischemia (13.3% vs. 19.6%, p = 0.08) and subsequent unscheduled repeat catheterization (7.6% vs. 13.3%, p = 0.05) but did not reduce the rate of infarct-related artery reocclusion (6.7% vs. 5.5%, p = 0.64), reinfarction (6.2% vs. 8.0%, p = 0.46) or mortality (4.3% vs. 3.1%) and was associated with a higher incidence of stroke (2.4% vs. 0%, p = 0.03). IABP use did not result in enhanced myocardial recovery as assessed by paired admission to predischarge and 6-week rest and exercise left ventricular ejection fraction.

CONCLUSIONS

In contrast to previous studies, a prophylactic IABP strategy after primary PTCA in hemodynamically stable high risk patients with AMI does not decrease the rates of infarct-related artery reocclusion or reinfarction, promote myocardial recovery or improve overall clinical outcome.