The Mortality Burden of Untreated Aortic Stenosis

BACKGROUND

The American College of Cardiology/American Heart Association guidelines recommend the assessment and grading of severity of aortic stenosis (AS) as mild, moderate, or severe, per echocardiogram, and recommend aortic valve replacement (AVR) when the AS is severe.

OBJECTIVES

The authors sought to describe mortality rates across the entire spectrum of untreated AS from a contemporary, large, real-world database.

METHODS

We analyzed a deidentified real-world data set including 1,669,536 echocardiographic reports (1,085,850 patients) from 24 U.S. hospitals (egnite Database, egnite). Patients >18 years of age were classified by diagnosed AS severity. Untreated mortality and treatment rates were examined with Kaplan-Meier (KM) estimates, with results compared using the log-rank test. Multivariate hazards analysis was performed to assess associations with all-cause mortality.

RESULTS

Among 595,120 patients with available AS severity assessment, the KM-estimated 4-year unadjusted, untreated, all-cause mortality associated with AS diagnosis of none, mild, mild-to-moderate, moderate, moderate-to-severe, or severe was 13.5% (95% CI: 13.3%-13.7%), 25.0% (95% CI: 23.8%-26.1%), 29.7% (95% CI: 26.8%-32.5%), 33.5% (95% CI: 31.0%-35.8%), 45.7% (95% CI: 37.4%-52.8%), and 44.9% (95% CI: 39.9%-49.6%), respectively. Results were similar when adjusted for informative censoring caused by treatment. KM-estimated 4-year observed treatment rates were 0.2% (95% CI: 0.2%-0.2%), 1.0% (95% CI: 0.7%-1.3%), 4.2% (95% CI: 2.0%-6.3%), 11.4% (95% CI: 9.5%-13.3%), 36.7% (95% CI: 31.8%-41.2%), and 60.7% (95% CI: 58.0%-63.3%), respectively. After adjustment, all degrees of AS severity were associated with increased mortality.

CONCLUSIONS

Patients with AS have high mortality risk across all levels of untreated AS severity. Aortic valve replacement rates remain low for patients with severe AS, suggesting that more research is needed to understand barriers to diagnosis and appropriate approach and timing for aortic valve replacement.

Design and rationale of the XIENCE short DAPT clinical program: An assessment of the safety of 3-month and 1-month DAPT in patients at high bleeding risk undergoing PCI with an everolimus-eluting stent

Dual antiplatelet therapy (DAPT) is key for the prevention of recurrent ischemic events after percutaneous coronary intervention (PCI); however, it increases the risk of bleeding complications. While new generation drug-eluting stents have been shown superior to bare-metal stents after a short DAPT course, the optimal DAPT duration in patients at high bleeding risk (HBR) remains to be determined. TRIAL DESIGN: The XIENCE Short DAPT program consists of three prospective, single-arm studies (XIENCE 90, XIENCE 28 Global and XIENCE 28 USA) investigating 3- or 1-month DAPT durations in HBR patients undergoing PCI with the XIENCE stent. The XIENCE 90 study is being conducted in the US and enrolled 2047 subjects who discontinued DAPT at 3 months if they were free from myocardial infarction (MI), repeat coronary revascularization, stroke, or stent thrombosis. The XIENCE 28 program includes the USA study, enrolling 642 patients in US and Canada, and the Global study, enrolling 963 patients in Europe and Asia. In XIENCE 28, patients were to discontinue DAPT at 1 month post-PCI if event-free. The primary hypothesis for both XIENCE 90 and XIENCE 28 is that a short DAPT regimen will be non-inferior to a conventional DAPT duration with respect to the composite of all-cause death or MI. Patients enrolled in the prospective multicenter post-market XIENCE V USA study will be used as historical control group in a stratified propensity-adjusted analysis. CONCLUSIONS: The XIENCE Short DAPT Program will provide insights into the safety and efficacy of 2 abbreviated DAPT regimens of 3- and 1-month duration in a large cohort of HBR patients undergoing PCI with the XIENCE stent.

P1854Clinical implications of physical function and resilience in patients undergoing transcatheter aortic valve implantation

Background

Gait speed, as a measure of physical function and marker of frailty, is now routinely screened when evaluating patients with aortic stenosis (AS) for transcatheter aortic valve implantation (TAVI). Assessment of physical function is important to identify patients for whom TAVI may be futile and to assign patients to a procedural risk category. After TAVI, patients may exhibit physical resilience (improvement in physical function) or vulnerability (worsening). Characterizing the trajectory and clinical consequences of physical function after TAVI represent knowledge gaps in the field.

Purpose

Evaluate associations between physical resilience (improved gait speed) vs vulnerability (decline) after TAVI and subsequent death/hospitalization.

Methods

The REPRISE III trial compared a mechanically-expanded vs a self-expanding valve in 912 high/extreme risk patients with symptomatic AS. Patients (n=587) who underwent valve implantation and who had a gait speed recorded both pre- and 1-year post-TAVI were analyzed. Gait speed is based on the 5m walk test (slow: 5m in >6s, <0.83m/s; normal: ≥0.83m/s). Trajectory of physical function after TAVI was characterized in 2 ways. Model 1 examined 4 groups based on slow or normal gait speeds at baseline and 1-year post-TAVI. Model 2 examined gait speed change pre-TAVI to 1 year (adjusted for baseline gait speed). Using a landmark approach, the relationships between baseline and 1-year gait speed were evaluated in multivariable Cox PH models of outcomes between 1 and 2 years post-TAVI.

Results

A clinically-meaningful improvement (≥0.1m/s), no change (±0.1m/s), or decline (≥0.1/ms) in gait speed 1 year after TAVI was observed in 39%, 36%, and 26% of patients, respectively. Among the 4 groups defined by pre- and 1-year post-TAVI gait speeds, 1 to 2 year mortality or hospitalization rates were: 6.6% (normal/normal), 20.9% (normal/slow), 8.0% (slow/normal), and 21.5% (slow/slow). Adjusted hazard ratios of the 2 models are shown (Table).

Table. Outcome by Change in Gait Speed Death/Hospitalization P-value Death P-value Hospitalization P-value Adjusted HR [95% CI] Adjusted HR [95% CI] Adjusted HR [95% CI] Model 1: Baseline/1 year Gait Speed   (Normal/Normal (n=150) [referent])   Normal/Slow (n=59) 3.82 [1.61, 9.08] <0.01 2.75 [0.96, 7.86] 0.06 7.31 [1.94, 27.58] <0.01   Slow/Normal (n=114) 1.39 [0.53, 3.59] 0.50 1.44 [0.50, 4.12] 0.50 1.69 [0.38, 7.60] 0.49   Slow/Slow (n=253) 3.88 [1.91, 7.91] <0.01 2.36 [1.02, 5.46] 0.045 3.89 [1.14, 13.27] 0.03 Model 2: Gait speed change   Baseline to 1 year per 0.1m/s increase 0.83 [0.74, 0.92] <0.01 0.92 [0.80, 1.04] 0.19 0.75 [0.64, 0.88] <0.01

Conclusion

These data reveal there is marked heterogeneity in the trajectory of physical function after TAVI and that this trajectory–more so than baseline physical function–is clinically consequential. Identifying and optimizing factors associated with physical resilience after TAVI may improve outcomes.

Acknowledgement/Funding

Boston Scientific

Percutaneous coronary intervention in unprotected left main disease: a status report

Percutaneous coronary intervention (PCI) of the unprotected left main (LM) artery is currently not recommended as a routine procedure based on the history of inferior outcomes of LM percutaneous transluminal coronary angioplasty and bare metal stenting. Instead, surgical revascularization (coronary artery bypass grafting, CABG) is considered to be the gold standard. There is renewed interest in LM-PCI because of improved outcomes of PCI utilizing drug eluting stents (DES) in multiple randomized trials. Several single-center non-randomized registries have evaluated the role of DES for LM-PCI. Data suggest a low mortality and target vessel failure of ostial LM or mid-shaft lesions in contrast to bifurcation lesions, which frequently require complex dual stenting techniques. The complex PCI in the bifurcation is associated with the increased occurrence of target vessel failure ranging from 2% and 38%. The rate of target vessel failure in bifurcation lesions is less in patients in whom the circumflex ostium is not involved so that single cross over stent is suitable. Current recommendations call for a follow-up angiography at 4-6 months to detect LM restenosis prior to a potentially fatal clinical event. The question of the duration of dual antiplatelet therapy in patients who underwent LM-PCI is unanswered. More registry data and randomized trials are needed before unprotected LM-PCI can be routinely offered to patients as an alternative to CABG.

Bivalirudin in acute coronary syndromes and percutaneous coronary intervention

The standard of care for patients with acute coronary syndrome is antithrombotic and antiplatelet therapies along with early percutaneous coronary intervention. Because of the limitations of heparin, there has been an interest in direct thrombin inhibitors, such as bivalirudin, which is now the anticoagulant of choice in percutaneous coronary intervention.

Effects of clopidogrel, aspirin and combined therapy in a porcine ex vivo model of high-shear induced stent thrombosis

AIMS

Use of ticlopidine in coronary stenting is limited by delayed onset of action. We studied the effects of clopidogrel, a rapidly acting analog of ticlopidine alone, and in combination with aspirin, in inhibiting stent thrombosis.

METHODS

Unpolished nitinol stents were deployed in a porcine ex vivo arteriovenous shunt and exposed to flowing arterial blood at a shear rate of approximately 1500. s-1. Stent thrombus, platelet aggregation and bleeding times were measured at baseline and after treatment.

RESULTS

Intravenous clopidogrel produced a rapid (within 30 min) and dose-dependent inhibition of stent thrombosis, with 87% reduction at a dose of 10 mg.kg-1 (P < 0.001). Aspirin alone (10 mg.kg-1) was minimally effective (20% inhibition P > 0.05) in inhibiting stent thrombosis. Combined treatment with clopidogrel and aspirin produced 95-98% inhibition of stent thrombosis, even at low doses of clopidogrel (2.5-5.0 mg.kg-1) (P < 0.0001). At effective doses both clopidogrel and combined therapy produced significant prolongation of bleeding time (P < 0.05) and inhibition of platelet aggregation (P < 0.05).

CONCLUSION

Clopidogrel, either alone or combined with aspirin, may have a potential role in preventing stent thrombosis in high-risk clinical situations.

Effects of GP IIb/IIIa receptor monoclonal antibody (7E3), heparin, and aspirin in an ex vivo canine arteriovenous shunt model of stent thrombosis

BACKGROUND

Thrombosis is an important limitation of metallic coronary stents, especially in smaller vessels in which shear rates are high. Monoclonal antibody to platelet glycoprotein IIb/IIIa receptor (7E3) has been shown to inhibit shear-induced platelet aggregation. In this study, we compared the effects of 7E3, heparin, and aspirin on stent thrombosis in an ex vivo arteriovenous shunt model of high-shear blood flow.

METHODS AND RESULTS

An ex vivo arteriovenous shunt was created in 10 anesthetized dogs. Control rough-surface slotted-tube nitinol stents (n = 72) expanded to 2 mm in diameter in a tubular perfusion chamber were interposed in the shunt and exposed to flowing arterial blood at a shear rate of 2100s-1 for 20 minutes. The animals were treated with intravenous murine 7E3 (Fab')2 (0.2, 0.4, and 0.8 mg/kg), heparin (100 U/kg), or aspirin (10 mg/kg). Effects of the test agents on thrombus weight, platelet aggregation, platelet P-selectin expression, bleeding time, and activated clotting time (ACT) were quantified. 7E3 reduced stent thrombosis by 95% (20 +/- 1 to 1 +/- 1 mg, P < .001) and platelet aggregation by 94% (14 +/- 2 to 1 +/- 1 omega, P < .001) at the highest dose (0.8 mg/kg). 7E3 significantly prolonged bleeding time but had no effect on ACT and platelet P-selectin expression. Heparin prolonged ACT but had no significant effect on stent thrombosis or platelet aggregation. Aspirin, although it inhibited platelet aggregation by 65%, had no effect on stent thrombosis (19 +/- 2 versus 20 +/- 1 mg in controls).

CONCLUSIONS

7E3 produced a dose-dependent inhibition of acute stent thrombosis under high-shear flow conditions. Stent thrombosis was resistant to heparin and aspirin. Thus, 7E3 may be an effective agent for preventing stent thrombosis.

Inhibition of acute stent thrombosis under high-shear flow conditions by a nitric oxide donor, DMHD/NO. An ex vivo porcine arteriovenous shunt study

BACKGROUND

Coronary stenting is limited by subacute thrombosis, especially in smaller-diameter vessels, in which shear rates are high. The objective of the present study was to determine whether local delivery of a new type of NO donor, the NO adduct of N,N'-dimethylhexanediamine (DMHD/NO), inhibits acute stent thrombosis (ST) at high-shear flow.

METHODS AND RESULTS

Effects of local infusion of DMHD/NO; intravenous aspirin, and heparin on ST were evaluated in an ex vivo porcine AV shunt model. Nitinol stents (2 mum in diameter, n = 120) were placed in a tubular chamber and perfused with blood from pigs (n = 13) at a shear rate of 2100s-1 for 20 minutes. ST was quantified by measurement of dry thrombus weight(TW). Effects on platelet aggregation (PA), blood pressure, bleeding time, and activated clotting time (ACT) were also examined. There was a dose-dependent inhibition of ST and PA by DMHD/NO. TW was reduced by 95% (1 +/- 2 versus 16 +/- 4 mg control, mean +/- SD, P < .001), and PA was reduced by 75% (4 +/- 3 versus 14 +/- 9 omega/min control, P < .05) at the highest dose of 10 mumol/L. DMHD/NO had no effects on bleeding time, ACT, or blood pressure. In contrast, aspirin (10 mg/kg), despite inhibiting PA, had no effects on TW (12 +/- 5 versus 16 +/- 8 mg control, P = .3). Heparin (200 U/kg) reduced TW by 33% (14 +/- 4 versus 21 +/- 3 mg control, P < .05) and prolonged ACT.

CONCLUSIONS

Local delivery of DMHD/NO produced a 15-fold inhibition of acute ST at high-shear flow without producing adverse systemic hemostatic or hemodynamic effects. Thus, treatment with DMHD/NO may be an effective strategy for prevention of stent thrombosis.

Prevention of Restenosis by Local Drug Delivery

Local drug therapy for preventing restenosis after angioplasty has been investigated for over a decade. Biologically active agents ranging from drugs to genes can be delivered locally using a wide variety of catheters. Microspheres, liposomes, and polymers have been used to enhance drug retention at the delivery site. More recently stents have been investigated as devices to attain local drug delivery, either by coating with polymers, seeding with genetically modified cells or by using them as a source of local radiation. Though the best method of delivering agents locally remains undefined, this approach is likely to emerge as an essential mode of therapy in the near future.

Female gender as a risk factor for torsades de pointes associated with cardiovascular drugs

OBJECTIVE

To test the hypothesis that female prevalence is greater than expected among reported cases of torsades de pointes associated with cardiovascular drugs that prolong cardiac repolarization.

DATA SOURCES

A MEDLINE search of the English-language literature for the period of 1980 through 1992, using the terms torsade de pointes, polymorphic ventricular tachycardia, atypical ventricular tachycardia, proarrhythmia, and drug-induced ventricular tachycardia, supplemented by pertinent references (dating back to 1964) from the reviewed articles and by personal communications with researchers involved in this field.

STUDY SELECTION

Ninety-three articles were identified describing at least one case of polymorphic ventricular tachycardia (with gender specified) associated with quinidine, procainamide hydrochloride, disopyramide, amiodarone, sotalol hydrochloride, bepridil hydrochloride, or prenylamine. A total of 332 patients were included in the analysis following application of prospectively defined criteria (eg, corrected QT [QTc] interval of 0.45 second or greater while receiving drug).

DATA EXTRACTION

Clinical and electrocardiographic descriptors were extracted for analysis. Expected female prevalence for torsades de pointes associated with quinidine, procainamide, disopyramide, and aminodarone was conservatively estimated from gender-specific data reported for antiarrhythmic drug prescriptions in 1986, as derived from the National Disease and Therapeutic Index, a large pharmaceutical database; expected female prevalence for torsades de pointes associated with sotalol, bepridil, and prenylamine was assumed to be 50% or less since these agents are prescribed for male-predominant cardiovascular conditions.

RESULTS

Women made up 70% (95% confidence interval, 64% to 75%) of the 332 reported cases of cardiovascular-drug-related torsades de pointes, and a female prevalence exceeding 50% was observed in 20 (83%) of 24 studies having at least four included cases. When analyzed according to various descriptors, women still constituted the majority (range, 51% to 94% of torsades de pointes cases), irrespective of the presence or absence of underlying coronary artery or rheumatic heart disease, left ventricular dysfunction, type of underlying arrhythmia, hypokalemia, hypomagnesemia, bradycardia, concomitant digoxin treatment, or level of QTc at baseline or while receiving drug. When cases of torsades de pointes were analyzed by individual drug, observed female prevalence was always greater than expected, representing a statistically significant difference (P < .05) for all agents except procainamide.

CONCLUSIONS

These findings strongly suggest that women are more prone than men to develop torsades de pointes during administration of cardiovascular drugs that prolong cardiac repolarization. The pathophysiological basis for, and therapeutic implications of, this gender disparity should be further investigated.