Efficacy and Safety of Appropriate Shocks and Antitachycardia Pacing in Transvenous and Subcutaneous Implantable Defibrillators: Analysis of All Appropriate Therapy in the PRAETORIAN Trial.

BACKGROUND: The PRAETORIAN trial (A Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) showed noninferiority of subcutaneous implantable cardioverter defibrillator (S-ICD) compared with transvenous implantable cardioverter defibrillator (TV-ICD) with regard to inappropriate shocks and complications. In contrast to TV-ICD, S-ICD cannot provide antitachycardia pacing for monomorphic ventricular tachycardia. This prespecified secondary analysis evaluates appropriate therapy and whether antitachycardia pacing reduces the number of appropriate shocks. METHODS: The PRAETORIAN trial was an international, investigator-initiated randomized trial that included patients with an indication for implantable cardioverter defibrillator (ICD) therapy. Patients with previous ventricular tachycardia <170 bpm or refractory recurrent monomorphic ventricular tachycardia were excluded. In 39 centers, 849 patients were randomized to receive an S-ICD (n=426) or TV-ICD (n=423) and were followed for a median of 49.1 months. ICD programming was mandated by protocol. Appropriate ICD therapy was defined as therapy for ventricular arrhythmias. Arrhythmias were classified as discrete episodes and storm episodes (≥3 episodes within 24 hours). Analyses were performed in the modified intention-to-treat population. RESULTS: In the S-ICD group, 86 of 426 patients received appropriate therapy, versus 78 of 423 patients in the TV-ICD group, during a median follow-up of 52 months (48-month Kaplan-Meier estimates 19.4% and 17.5%; P=0.45). In the S-ICD group, 83 patients received at least 1 shock, versus 57 patients in the TV-ICD group (48-month Kaplan-Meier estimates 19.2% and 11.5%; P=0.02). Patients in the S-ICD group had a total of 254 shocks, compared with 228 shocks in the TV-ICD group (P=0.68). First shock efficacy was 93.8% in the S-ICD group and 91.6% in the TV-ICD group (P=0.40). The first antitachycardia pacing attempt successfully terminated 46% of all monomorphic ventricular tachycardias, but accelerated the arrhythmia in 9.4%. Ten patients with S-ICD experienced 13 electrical storms, versus 18 patients with TV-ICD with 19 electrical storms. Patients with appropriate therapy had an almost 2-fold increased relative risk of electrical storms in the TV-ICD group compared with the S-ICD group (P=0.05). CONCLUSIONS: In this trial, no difference was observed in shock efficacy of S-ICD compared with TV-ICD. Although patients in the S-ICD group were more likely to receive an ICD shock, the total number of appropriate shocks was not different between the 2 groups. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022.

Subcutaneous or Transvenous Defibrillator Therapy.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (ICD) was designed to avoid complications related to the transvenous ICD lead by using an entirely extrathoracic placement. Evidence comparing these systems has been based primarily on observational studies. METHODS: We conducted a noninferiority trial in which patients with an indication for an ICD but no indication for pacing were assigned to receive a subcutaneous ICD or transvenous ICD. The primary end point was the composite of device-related complications and inappropriate shocks; the noninferiority margin for the upper boundary of the 95% confidence interval for the hazard ratio (subcutaneous ICD vs. transvenous ICD) was 1.45. A superiority analysis was prespecified if noninferiority was established. Secondary end points included death and appropriate shocks. RESULTS: A total of 849 patients (426 in the subcutaneous ICD group and 423 in the transvenous ICD group) were included in the analyses. At a median follow-up of 49.1 months, a primary end-point event occurred in 68 patients in the subcutaneous ICD group and in 68 patients in the transvenous ICD group (48-month Kaplan-Meier estimated cumulative incidence, 15.1% and 15.7%, respectively; hazard ratio, 0.99; 95% confidence interval [CI], 0.71 to 1.39; P = 0.01 for noninferiority; P = 0.95 for superiority). Device-related complications occurred in 31 patients in the subcutaneous ICD group and in 44 in the transvenous ICD group (hazard ratio, 0.69; 95% CI, 0.44 to 1.09); inappropriate shocks occurred in 41 and 29 patients, respectively (hazard ratio, 1.43; 95% CI, 0.89 to 2.30). Death occurred in 83 patients in the subcutaneous ICD group and in 68 in the transvenous ICD group (hazard ratio, 1.23; 95% CI, 0.89 to 1.70); appropriate shocks occurred in 83 and 57 patients, respectively (hazard ratio, 1.52; 95% CI, 1.08 to 2.12). CONCLUSIONS: In patients with an indication for an ICD but no indication for pacing, the subcutaneous ICD was noninferior to the transvenous ICD with respect to device-related complications and inappropriate shocks. (Funded by Boston Scientific; PRAETORIAN ClinicalTrials.gov number, NCT01296022.).

Cardiac sequelae in athletes following COVID-19 vaccination: evidence and misinformation.

The recognition of myocarditis as a rare side effect of SARS-CoV-2 mRNA vaccination has sparked a global debate on vaccine safety, especially in the realm of sports. The main proposed mechanisms in the pathogenesis of COVID-19 mRNA vaccination-associated myocarditis (C-VAM) are based on the activation of the innate- and adaptive immune system against a susceptible immune-genetic background, including the recognition of mRNA as an antigen by the immune system, molecular mimicry between SARS-CoV-2 spike glycoprotein and cardiac tissue antigens and inflammatory sex-hormone signalling. The relatively younger age of the athlete population hypothetically constellates an increased risk of C-VAM. A subgroup analysis in individuals under 40 years revealed a low incidence of myocarditis following COVID-19 mRNA vaccination when compared to positive SARS-CoV-2 tests. No confirmed cases of athletes experiencing cardiac complications after mRNA vaccination have been reported. Most athletes only reported mild side effects after COVID-19 vaccination. A small but statistically significant decrease in maximal oxygen consumption in recreational athletes occurred after BNT162b2 mRNA booster vaccine administration. The clinical relevance and temporality of which remain to be determined. Many speculative social media reports attribute sudden cardiac arrest/death (SCA/D) in athletes to mRNA vaccination. Large media outlets have thoroughly debunked these claims. There is currently no evidence to support the claim that COVID-19 mRNA vaccination increases the risk of myocardial sequelae or SCA/D in athletes. However, specific vaccine regimen selection and timing may be appropriate to prevent detrimental performance effects.

Device-related complications in subcutaneous versus transvenous ICD: a secondary analysis of the PRAETORIAN trial.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (S-ICD) is developed to overcome lead-related complications and systemic infections, inherent to transvenous ICD (TV-ICD) therapy. The PRAETORIAN trial demonstrated that the S-ICD is non-inferior to the TV-ICD with regard to the combined primary endpoint of inappropriate shocks and complications. This prespecified secondary analysis evaluates all complications in the PRAETORIAN trial. METHODS AND RESULTS: The PRAETORIAN trial is an international, multicentre, randomized trial in which 849 patients with an indication for ICD therapy were randomized to receive an S- ICD (N = 426) or TV-ICD (N = 423) and followed for a median of 49 months. Endpoints were device-related complications, lead-related complications, systemic infections, and the need for invasive interventions. Thirty-six device-related complications occurred in 31 patients in the S-ICD group of which bleedings were the most frequent. In the TV-ICD group, 49 complications occurred in 44 patients of which lead dysfunction was most frequent (HR: 0.69; P = 0.11). In both groups, half of all complications were within 30 days after implantation. Lead-related complications and systemic infections occurred significantly less in the S-ICD group compared with the TV-ICD group (P < 0.001, P = 0.03, respectively). Significantly more complications required invasive interventions in the TV-ICD group compared with the S-ICD group (8.3% vs. 4.3%, HR: 0.59; P = 0.047). CONCLUSION: This secondary analysis shows that lead-related complications and systemic infections are more prevalent in the TV-ICD group compared with the S-ICD group. In addition, complications in the TV-ICD group were more severe as they required significantly more invasive interventions. This data contributes to shared decision-making in clinical practice.

Development and external validation of prediction models to predict implantable cardioverter-defibrillator efficacy in primary prevention of sudden cardiac death.

AIMS: This study was performed to develop and externally validate prediction models for appropriate implantable cardioverter-defibrillator (ICD) shock and mortality to identify subgroups with insufficient benefit from ICD implantation. METHODS AND RESULTS: We recruited patients scheduled for primary prevention ICD implantation and reduced left ventricular function. Bootstrapping-based Cox proportional hazards and Fine and Gray competing risk models with likely candidate predictors were developed for all-cause mortality and appropriate ICD shock, respectively. Between 2014 and 2018, we included 1441 consecutive patients in the development and 1450 patients in the validation cohort. During a median follow-up of 2.4 (IQR 2.1-2.8) years, 109 (7.6%) patients received appropriate ICD shock and 193 (13.4%) died in the development cohort. During a median follow-up of 2.7 (IQR 2.0-3.4) years, 105 (7.2%) received appropriate ICD shock and 223 (15.4%) died in the validation cohort. Selected predictors of appropriate ICD shock were gender, NSVT, ACE/ARB use, atrial fibrillation history, Aldosterone-antagonist use, Digoxin use, eGFR, (N)OAC use, and peripheral vascular disease. Selected predictors of all-cause mortality were age, diuretic use, sodium, NT-pro-BNP, and ACE/ARB use. C-statistic was 0.61 and 0.60 at respectively internal and external validation for appropriate ICD shock and 0.74 at both internal and external validation for mortality. CONCLUSION: Although this cohort study was specifically designed to develop prediction models, risk stratification still remains challenging and no large group with insufficient benefit of ICD implantation was found. However, the prediction models have some clinical utility as we present several scenarios where ICD implantation might be postponed.

Myocardial Bridging as a Trigger in Angina With No Obstructive Coronary Artery Disease.

We present 2 patients with angina with no obstructive coronary artery disease and concomitant myocardial bridging. Despite maximal tolerated pharmacotherapy, symptoms remained. Invasive anatomical and hemodynamic assessment identified myocardial bridging as a contributing cause of angina. Following heart team discussion, both patients underwent successful coronary artery unroofing of the left anterior descending artery.

Safety of Sports for Patients with Subcutaneous Implantable Cardioverter Defibrillator (SPORT S-ICD): study rationale and protocol.

Background: Recent studies suggest that participation in recreational and even competitive sports is generally safe for patients with implantable cardioverter-defibrillators (ICDs). However, these studies included only patients with implanted transvenous ICD (TV-ICD). Nowadays, subcutaneous ICD (S-ICD) is a safe and effective alternative and is increasingly implanted in younger ICD candidates. Data on the safety of sport participation for patients with implanted S-ICD systems is urgently needed. Objectives: The goal of the study is to quantify the risks (or determine the safety) of sports participation for athletes with an S-ICD, which will guide shared decision making for athletes requiring an ICD and/or wishing to return to sports after implantation. Methods: The SPORT S-ICD (Sports for Patients with Subcutaneous Implantable Cardioverter Defibrillator) study is an international, multicenter, prospective, noninterventional, observational study, designed specifically to collect data on the safety of sports participation among patients with implanted S-ICD systems who regularly engage in sports activities. Results: A total of 450 patients will undergo baseline assessment including baseline characteristics, indication for S-ICD implantation, arrhythmic history, S-ICD data and programming, and data regarding sports activities. LATITUDE Home Monitoring information will be regularly transferred to the study coordinator for analysis. Conclusion: The results of the study will aid in shaping clinical decision making, and if the tested hypothesis will be proven, it will allow the safe continuation of sports for patients with an implanted S-ICD.

Predictive value of the PRAETORIAN score for defibrillation test success in patients with subcutaneous ICD: A subanalysis of the PRAETORIAN-DFT trial.

BACKGROUND: The PRAETORIAN score estimates the risk of failure of subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy by using generator and lead positioning on bidirectional chest radiographs. The PRospective randomized compArative trial of subcutanEous implanTable cardiOverter-defibrillatoR ImplANtation with and without DeFibrillation Testing (PRAETORIAN-DFT) investigates whether PRAETORIAN score calculation is noninferior to defibrillation testing (DFT) with regard to first shock efficacy in spontaneous events. OBJECTIVE: This prespecified subanalysis assessed the predictive value of the PRAETORIAN score for defibrillation success in induced ventricular arrhythmias. METHODS: This multicenter investigator-initiated trial randomized 965 patients between DFT and PRAETORIAN score calculation after de novo S-ICD implantation. Successful DFT was defined as conversion of induced ventricular arrhythmia in <5 seconds from shock delivery within 2 attempts. Bidirectional chest radiographs were obtained after implantation. The predictive value of the PRAETORIAN score for DFT success was calculated for patients in the DFT arm. RESULTS: In total, 482 patients were randomized to undergo DFT. Of these patients, 457 (95%) underwent DFT according to protocol, of whom 445 (97%) had successful DFT and 12 (3%) had failed DFT. A PRAETORIAN score of ≥90 had a positive predictive value of 25% for failed DFT, and a PRAETORIAN score of <90 had a negative predictive value of 99% for successful DFT. A PRAETORIAN score of ≥90 was the strongest independent predictor for failed DFT (odds ratio 33.77; confidence interval 6.13-279.95; P < .001). CONCLUSION: A PRAETORIAN score of <90 serves as a reliable indicator for DFT success in patients with S-ICD, and a PRAETORIAN score of ≥90 is a strong predictor for DFT failure.

Accelerated Idioventricular Rhythm in a Young Athlete: Physiology or Pathology?

An accelerated idioventricular rhythm was seen on a routine preparticipation electrocardiogram of a 19-year-old healthy and symptom-free athlete. Family history was negative for cardiac disease. Additional investigations revealed a hypertrophic cardiomyopathy, confirmed with cardiac magnetic resonance imaging and genetic analysis. Accelerated idioventricular rhythm in young athletes warrants careful clinical evaluation. (Level of Difficulty: Advanced.).

The Sports Cardiology Team: Personalizing Athlete Care Through a Comprehensive, Multidisciplinary Approach.

Objective: To systematically investigate and document the infrastructure, practices, recommendations, and clinical consequences of a structured, organized sports cardiology multidisciplinary team (MDT) for athletes and patients who wish to engage in sports and exercise. Patients and Methods: We established bimonthly sports cardiology MDT meetings, with a permanent panel of experts in sports cardiology, genetics, pediatric cardiology, cardiovascular imaging, electrophysiology, and sports and exercise medicine. Cases were referred nationally or internationally by cardiologists/sports physicians. We retrospectively analyzed all MDT cases (April 10, 2019 through May 13, 2020) and collected clinical follow-up data up to 1 year after the initial review. Results: A total of 115 athletes underwent MDT review; of them, 11% were women, 65% were recreational athletes, and 54% were performing "mixed" type of sports; the mean age was 32±16 years. An MDT review led to a diagnosis revision of "suspected cardiac pathology" to "no cardiac pathology" in 38% of the athletes and increased the number of definitive diagnoses (from 77 to 109; P=.03). We observed fewer "total sports restrictions" (from 6 to 0; P=.04) and more tailored sports advice concerning "no peak load/specific maximum load" (from 10 to 26; P=.02). At the 14±6-month follow-up, 112 (97%) athletes reported no cardiovascular events, 111 (97%) athletes reported no (new) cardiac symptoms, 113 (98%) athletes reported adherence to the MDT sports advice, and no diagnoses were revised. Conclusion: Our experiences with a comprehensive sports cardiology MDT demonstrate that this approach leads to higher percentages of definitive diagnoses and fewer cardiac pathology diagnoses, more tailored sports advice with excellent rates of adherence, and fewer total sports restrictions. Our findings highlight the added value of sports cardiology MDTs for patient and athlete care.

Anticoagulants and their reversal.

In an exciting era with many alternatives to the old anticoagulants heparin and warfarin emerging on the scene, awareness of the possibility to reverse their effect is mandatory. In this review, the traditional antidotes for warfarin (vitamin K, plasma, and prothrombin complex concentrate) and for heparin (protamine) are described together with the newer alternatives (recombinant activated factor VII, concatameric peptides, and recombinant platelet factor 4). For some of the newer anticoagulants, possible antidotes have been identified, whereas other alternatives have been discarded. There is a very limited experience of deamino-d-arginine vasopressin or a von Willebrand factor VIII concentrate to counteract hirudin. The small direct thrombin inhibitors may be reversed with activated prothrombin complex concentrate but not with recombinant activated factor VII, whereas the latter agent appears to be effective against the pentasaccharides and the recombinant nematode anticoagulant protein C2. Additional options that may become available in the future are also discussed briefly.

Ability of recombinant factor VIIa to reverse the anticoagulant effect of the pentasaccharide fondaparinux in healthy volunteers.

BACKGROUND: The novel anticoagulant fondaparinux proved to be effective and safe in the postoperative prevention of venous thrombosis. Current phase III trials with this synthetic selective factor Xa inhibitor focus on its use in the treatment of patients with venous and arterial thrombosis. As with any anticoagulant therapy, there is a risk of bleeding complications; hence, a strategy to reverse the effects of fondaparinux is desirable. The aim of this study was to investigate whether recombinant factor VIIa (rFVIIa) could neutralize the anticoagulant effects of subcutaneously administered fondaparinux. METHODS AND RESULTS: In a randomized, placebo-controlled design, 16 healthy male subjects received either a single subcutaneous dose of fondaparinux (10 mg) and a single intravenous bolus of rFVIIa (90 microg/kg; n=8), fondaparinux and placebo (n=4), or placebo and rFVIIa (n=4). Fondaparinux (or placebo) was administered 2 hours before rFVIIa (or placebo). Injection of rFVIIa after fondaparinux normalized the prolonged activated partial thromboplastin and prothrombin times and reversed the decrease in prothrombin activation fragments 1+2 (F(1+2)), as observed with fondaparinux alone. Thrombin-generation time and endogenous thrombin potential, which were inhibited by fondaparinux, normalized up to 6 hours after rFVIIa injection. CONCLUSIONS: rFVIIa is capable of normalizing coagulation times and thrombin generation during fondaparinux treatment. The duration of this effect ranged from 2 to 6 hours after rFVIIa injection. These results suggest that rFVIIa may be useful to reverse the anticoagulant effect of fondaparinux in case of serious bleeding complications or need for acute surgery during treatment with fondaparinux.

Recurrent cardiac ischemic events early after discontinuation of short-term heparin treatment in acute coronary syndromes: results from the Thrombolysis in Myocardial Infarction (TIMI) 11B and Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q-Wave Coronary Events (ESSENCE) studies.

OBJECTIVES: The aim of this study was to determine whether discontinuation of low-molecular-weight heparin (LMWH) treatment results in a clustering of cardiac ischemic events as previously observed after cessation of unfractionated heparin (UFH) in acute coronary syndrome (ACS) patients. BACKGROUND: Clinical trials in patients with ACS have shown early recurrent ischemic events after discontinuation of UFH treatment. We analyzed whether LMWH cessation also results in early ischemic recurrence events and if continuation of a fixed-dose LMWH prevents this complication. METHODS: The combined incidence of death, myocardial infarction, or urgent revascularization in the first seven days after discontinuation of UFH (n = 3,012), short-term enoxaparin 1 mg/kg subcutaneously twice a day (n = 2,011), and short-term enoxaparin followed by prolonged enoxaparin 60 mg subcutaneously twice a day (n = 1,075) was analyzed from the combined Thrombolysis In Myocardial Infarction (TIMI) 11B/Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q-Wave Coronary Events (ESSENCE) database in a per patient analysis. RESULTS: The cessation of both UFH and short-term enoxaparin resulted in a similar clustering of recurrent ischemic events on the first day, with an incidence of the primary end point of 2.8% in both groups. Of all recurrent events in the first week after cessation, 40% occurred in the first 24 h. The continuation of a fixed-dose enoxaparin treatment prevented this early excess, with a first day incidence of 0.4% (p < 0.0001). The TIMI risk score characteristics predicted the incidence of early rebound ischemic events. CONCLUSIONS: There is significant clustering of recurrent ischemic events within 24 h after cessation of both short-term UFH and enoxaparin treatment, and patients should be carefully monitored during that period. This early rebound may be prevented by continuation of a fixed dose of enoxaparin.

Rebound thrombin generation after heparin therapy in unstable angina. A randomized comparison between unfractionated and low-molecular-weight heparin.

OBJECTIVES: This study compared rebound coagulation in patients with acute coronary syndrome patients after discontinuation of unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH). BACKGROUND: Up to a quarter of patients hospitalized for unstable angina experience recurrent ischemia after discontinuation of UFH or LMWH therapy, which may be the result of rebound coagulation activation and subsequent thrombosis. It is unknown whether UFH and LMWH differ in this respect. METHODS: We randomized 71 patients admitted with unstable angina to intravenous UFH or subcutaneous LMWH (dalteparin) and measured plasma markers of coagulation before, during, and after treatment. RESULTS: A complete series of measurements was obtained in 59 patients. Plasma prothrombin fragment 1+2 (F(1+2)) levels decreased in both groups during treatment. After loss of therapeutic plasma drug levels, F(1+2) increased (within 3 h) to a maximum level at 12 to 24 h that was higher than before or during treatment in both groups (p < 0.0001). In both groups, F(1+2) levels remained higher than pretreatment up to 24 h after discontinuation. Similarly, thrombin-antithrombin (TAT) levels exceeded treatment and pretreatment levels, at a slower rate after dalteparin than after UFH. However, after dalteparin a higher peak value of TAT was observed. CONCLUSIONS: Rebound coagulation activation occurs within hours after discontinuation of both UFH and dalteparin. With both drugs, thrombin generation is significantly greater after treatment than before or during treatment. A longer duration or weaning of treatment, or continuation with another anticoagulant treatment, may reduce rebound coagulation activation and ischemic events.

Recombinant nematode anticoagulant protein c2, an inhibitor of the tissue factor/factor VIIa complex, in patients undergoing elective coronary angioplasty.

OBJECTIVES: We investigated the safety and pharmacodynamics of escalating doses of recombinant nematode anticoagulant protein c2 (rNAPc2) in patients undergoing elective coronary angioplasty. BACKGROUND: Recombinant NAPc2 is a potent inhibitor of the tissue factor/factor VIIa complex, which has the potential to reduce the risk of thrombotic complications in coronary artery disease. METHODS: In a randomized, double-blinded, dose-escalation, multicenter trial, 154 patients received placebo or rNAPc2 at doses of 3.5, 5.0, 7.5, and 10.0 microg/kg body weight as a single subcutaneous administration 2 to 6 h before angioplasty. All patients received aspirin, unfractionated heparin during angioplasty, and clopidogrel in case of stent implantation. RESULTS: Minor bleeding rates for the doses 3.5 to 7.5 microg/kg were comparable to that with placebo (6.7%), whereas an incidence of 26.9% was observed at the 10.0 microg/kg dose level (p < 0.01). Major bleedings occurred in the 5.0 microg/kg (n = 3) and 7.5 microg/kg (n = 1) dose groups. The three patients in the 5.0 microg/kg dose group also received a glycoprotein IIb/IIIa receptor inhibitor at the moment of major bleeding. Systemic thrombin generation, as measured by prothrombin fragment 1+2 (F(1+2)), was suppressed in all rNAPc2 dose groups to levels below pretreatment values for at least 36 h. In the placebo group, a distinct increase of F(1+2) levels was observed following cessation of heparin. CONCLUSIONS: Inhibition of the tissue factor/factor VIIa complex with rNAPc2, at doses up to 7.5 microg/kg, in combination with aspirin, clopidogrel, and unfractionated heparin appears to be a safe and effective strategy to prevent thrombin generation during coronary angioplasty.

The impact on coagulation of an intravenous loading dose in addition to a subcutaneous regimen of low-molecular-weight heparin in the initial treatment of acute coronary syndromes.

OBJECTIVES: We sought to quantify the impact of adding an intravenous loading dose to a subcutaneous regimen of enoxaparin in patients with an acute coronary syndrome (ACS). BACKGROUND: It is unclear whether an intravenous (i.v.) loading dose of enoxaparin should be added to a subcutaneous (s.c.) regimen in patients with ACS. METHODS: Patients admitted with ACS were randomized to i.v.+s.c.(n = 14) or s.c. alone (n = 11) enoxaparin treatment. Coagulation markers were measured at nine time points during the first 24 h of treatment. RESULTS: The i.v.+s.c. therapy immediately resulted in therapeutic anti-Xa levels, which remained significantly higher for 6 h compared with s.c. alone, without reaching excessively high levels. A rapid decrease of plasma prothrombin fragments 1+2 (F(1+2)) levels was observed as soon as 5 min after the i.v. injection (33% lower; p = 0.007), and these levels remained lower up to 2 h after the start of treatment compared with SQ alone. The ex vivo thrombin generation time was maximally prolonged at 5 min post-injection in the i.v.+s.c. group and remained significantly prolonged up to 6 h post-injection compared with s.c. alone. The tissue factor pathway inhibitor plasma activity was immediately increased by 194% with i.v.+s.c., whereas the maximum increase with s.c. alone was 47% at 3 h. CONCLUSIONS: Therapeutic plasma levels of enoxaparin are achieved significantly earlier by an i.v.+s.c. regimen compared with s.c. alone, without leading to unacceptably high levels. As the risk of thrombotic complications is greatest early after admission, the observed differences in antithrombotic effects may translate into a clinical benefit. However, this remains to be established.

Recombinant factor VIIa reverses the anticoagulant effect of the long-acting pentasaccharide idraparinux in healthy volunteers.

We investigated whether the anticoagulant effect of idraparinux, a selective long-acting factor Xa inhibitor, could be neutralized by recombinant factor VIIa (rFVIIa) in healthy male volunteers. We performed a randomized, placebo-controlled trial, comparing idraparinux [7.5 mg subcutaneous (s.c.)] followed at 3 h by rFVIIa [90 microg/kg intravenous (i.v.)] (n = 6), or idraparinux (7.5 mg s.c) followed after 1 week by rFVIIa (90 microg/kg i.v.)(n = 6). rFVIIa, given 3 h after idraparinux, significantly reversed the increased thrombin generation time (TGT), the increased activated partial thromboplastin time (aPTT) and prothrombin time (PT), and the reduced prothrombin fragment 1+2 (F1+2) levels caused by idraparinux, although no clear effect of rFVIIa on the endogenous thrombin potential (ETP) was observed. One week after idraparinux, injection of rFVIIa resulted in a similar relative reduction of the remaining increased aPTT, PT and TGT, with correction to pre-idraparinux values. A clear increase of F1+2 was observed, together with a small increase in ETP. We conclude that rFVIIa has significant effects on the idraparinux-inhibited thrombin generation and clotting parameters. These results suggest that rFVIIa may be useful in serious bleeding complications in idraparinux treated patients.