Long-term clinical experience with the Omnicarbon prosthetic valve

Clinical evaluation of new heart valve prostheses: update of objective performance criteria

This article summarizes the long-term clinical results of the Food and Drug Administration-approved heart valves, provides current updates to the objective performance criteria (OPC) used to evaluate new heart valve prostheses, and documents the steps that the International Organization for Standardization Committee used to arrive at the updated OPC. Data were extracted from 19 Food and Drug Administration summaries of safety and effectiveness data reports (31 series) and 56 literature articles (85 series) published from 1999 to 2012. The OPC were calculated for five valve-related complications by valve type (mechanical and bioprosthetic) and valve position (aortic and mitral).

A Six-Year Experience with the Omnicarbon Valve in North American Patients

AIM

We studied the results of an all-carbon monoleaflet valve prosthesis (the Omnicarbon) in a North American population.

METHODS

Patients were recalled to our valve clinic for complete evaluation, including echocardiography, laboratory tests, and physician examination. This experience includes 108 Omnicarbon valve implants. We report the results of single aortic (AVR) or mitral (MVR) valve replacement.

RESULTS

Patients' ages ranged from 40 to 83 (mean: 63 +/- 9 years), and most were male (60%, 59/98). Preoperatively, 71% were NYHA Classes III/IV, while most patients are now Classes I/II (86%). AVR predominated (63%, 62/98), and many patients (44%, 43/98) underwent cardiac procedures either previously or concomitant with valve replacement. Hospital mortality was 6.1% (6/98). Predicted hospital mortality using the Parsonnet additive risk model averaged 12.1%. Currently, four patients cannot be located (96% accountability). Overall, hematology indicated low hemolysis-lactate dehydrogenase: 691 +/- 184 IU/L (112%+/- 30% upper normal), reticulocytes: 1.8%+/- 0.7%, and red blood cells (10(6)/mm(3)): 4.41 +/- 0.50 (males)/4.16 +/- 0.50 (females). International normalized ratio averaged 2.67 +/- 0.72. Doppler echocardiography values were acceptable and comparable to other mechanical valves. Five-year survival (hospital death included) is 86%+/- 4%. At 5 years, freedom from any thromboembolic event is 99%+/- 1%, and freedom from bleeding is 97%+/- 2%. Endocarditis and nonstructural dysfuction also occurred at low rates (99%+/- 1% freedom at five years), and no structural failure or hemolytic anemia was observed during the 343 patient-years (mean: 3.7 +/- 1.6 years).

CONCLUSIONS

Good hematology and hemodynamics, along with remarkably low complication rates, demonstrate that the Omnicarbon valve meets contemporary performance expectations.

Antithrombotic Therapy in Valvular Heart Disease—Native and Prosthetic

This chapter about antithrombotic therapy in native and prosthetic valvular heart disease is part of the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following: For patients with rheumatic mitral valve disease and atrial fibrillation (AF), or a history of previous systemic embolism, we recommend long-term oral anticoagulant (OAC) therapy (target international normalized ratio [INR], 2.5; range, 2.0 to 3.0) [Grade 1C+]. For patients with rheumatic mitral valve disease with AF or a history of systemic embolism who suffer systemic embolism while receiving OACs at a therapeutic INR, we recommend adding aspirin, 75 to 100 mg/d (Grade 1C). For those patients unable to take aspirin, we recommend adding dipyridamole, 400 mg/d, or clopidogrel (Grade 1C). In people with mitral valve prolapse (MVP) without history of systemic embolism, unexplained transient ischemic attacks (TIAs), or AF, we recommended against any antithrombotic therapy (Grade 1C). In patients with MVP and documented but unexplained TIAs, we recommend long-term aspirin therapy, 50 to 162 mg/d (Grade 1A). For all patients with mechanical prosthetic heart valves, we recommend vitamin K antagonists (Grade 1C+). For patients with a St. Jude Medical (St. Paul, MN) bileaflet valve in the aortic position, we recommend a target INR of 2.5 (range, 2.0 to 3.0) [Grade 1A]. For patients with tilting disk valves and bileaflet mechanical valves in the mitral position, we recommend a target INR of 3.0 (range, 2.5 to 3.5) [Grade 1C+]. For patients with caged ball or caged disk valves, we suggest a target INR of 3.0 (range, 2.5 to 3.5) in combination with aspirin, 75 to 100 mg/d (Grade 2A). For patients with bioprosthetic valves, we recommend vitamin K antagonists with a target INR of 2.5 (range, 2.0 to 3.0) for the first 3 months after valve insertion in the mitral position (Grade 1C+) and in the aortic position (Grade 2C). For patients with bioprosthetic valves who are in sinus rhythm and do not have AF, we recommend long-term (> 3 months) therapy with aspirin, 75 to 100 mg/d (Grade 1C+).

The optimal intensity of vitamin K antagonists in patients with mechanical heart valves: a meta-analysis

OBJECTIVES

The purpose of this study was to compare two different intensities of vitamin K antagonists (VKA) among patients with mechanical heart valves using meta-analytic techniques.

BACKGROUND

Patients with mechanical heart valves are at increased risk for valve thrombosis and systemic embolism, which can be reduced by VKA. The range of optimal intensity of VKA is still a matter of debate.

METHODS

A computerized search in the PubMed database was made for relevant articles. A meta-analysis was performed of all eligible studies with data on the incidences of thromboembolic and bleeding complications in patients with mechanical heart valve prostheses during different intensities of VKA therapy. The studies were classified into low-intensity VKA therapy (mean target international normalized ratio [INR] of 3.0 or lower) or high-intensity VKA therapy (mean target INR above 3.0).

RESULTS

Thirty-five eligible studies were identified, including in total 23,145 patients, who were studied for 108,792 patient-years. For patients with an aortic valve, high intensity resulted in a lower incidence of thromboembolic events (risk ratio [RR] = 0.73, p < 0.0001); however, the incidence of bleeding was increased (RR = 1.23, p < 0.0001). In the mitral valve group, the incidence rate for thromboembolism was lower in the high-intensity group (RR = 0.74, p < 0.0001), without a significantly increased bleeding incidence (RR = 1.08, p = 0.0524). The total number of thromboembolic and bleeding events was decreased in the high-intensity group compared with low-intensity VKA therapy for both aortic and mitral valve prostheses (RR = 0.94 [p = 0.0067] and 0.84 [p < 0.0001]), respectively.

CONCLUSIONS

This meta-analysis shows that both aortic and mitral valves will benefit from a treatment strategy with a target INR higher than 3.0.

Early in vivo hemodynamic results after aortic valve replacement with the St Jude Medical Regent mechanical heart valve in patients with pure aortic stenosis

BACKGROUND

The St Jude Medical Regent is a new-generation mechanical heart valve that represents a design evolution of the St Jude Hemodynamic Plus Series (HP). The purpose of this study was to evaluate early "in vivo" hemodynamic performance of the Regent valve in patients with aortic stenosis.

METHODS

Between March 2000 and December 2001, 32 patients (mean age 59.9 +/- 5.9,56.3% male) with pure aortic stenosis received a Regent mechanical prosthesis in the aortic position. Hemodynamic performance was assessed by Doppler echocardiography at discharge, two months, six months, and one year by calculating peak transprosthetic velocity (Vmax), mean (MG) and peak (PG) transprosthetic gradients, effective orifice area index (EOAI), left ventricular mass index (LVMI), and degree of aortic regurgitation.

RESULTS

A significant reduction in mean and peak transaortic gradients (p < 0.001) and a significant increase in EOAI (p < 0.001) over time followed valve replacement, and a bivariate analysis of variance (ANOVA) failed to demonstrate statistical differences by valve size over time (p = ns). A significant reduction in left ventricular hypertrophy occurred over time (p < 0.001) in all valve sizes (p = ns between groups): baseline LVMI was 221 +/- 57 g/cm2; it decreased by 30 g/cm2 (p < 0.001) at discharge. LVMI decreased from 191 +/- 54 g/cm2 to 161 +/- 41 g/cm2 (p < 0.001) from discharge to two months. Further reductions were not significant. At the six-month follow-up no patient in our cohort exhibited moderate or severe aortic regurgitation at Doppler echocardiography.

CONCLUSIONS

Early results with the St Jude Medical Regent valve have been satisfactory. Further assessments are necessary to confirm these results.

Single-center experience with the bicarbon bileaflet prosthetic heart valve in Japan

We analyzed midterm results using the Bicarbon valve in a single center. Forty-four patients had aortic valve replacement (AVR), 48 had mitral valve replacement (MVR), and 13 had both aortic and mitral valve replacement (DVR). The mean age of the 105 patients was 61.2 +/- 11.3 years. The mean follow-up was 1.8 +/- 1.1 years with a cumulative follow-up of 188 patient-years. There were 5 early deaths (4.7%: 4 in the AVR group and 1 in the MVR group) and 5 late deaths (2.7% per patient-year: 3 malignancy, 1 cerebral hemorrhage, 1 myocardial infarction). Survival at 3 years was 91 +/- 4% in the AVR group, 92 +/- 5% in the MVR group, and 66 +/- 23% in the DVR group. The linearized incidence of thromboembolic complications, hemorrhagic complications, and paravalvular leaks in all patients was 1.06 +/- 2.34%, 1.60 +/- 2.53%, and 0.53 +/- 2.22% per patient-year, respectively. No other complications were observed. In conclusion, the Bicarbon prosthetic heart valve has shown excellent clinical results associated with a low incidence of valve-related complications.

Microembolic signal counts increase during hyperbaric exposure in patients with prosthetic heart valves

BACKGROUND

Patients with prosthetic heart valves have an increased risk of thromboembolic events, and transcranial Doppler sonography reveals microembolic signals. Whereas microembolic signals were initially assumed to be of particulate matter, recent studies suggest that they are partially gaseous in origin. If this is true, alteration of environmental pressure should change microembolic signal counts. We undertook this study to evaluate the influence of hyperbaric exposure on microembolic signal counts in persons with prosthetic heart valves.

METHODS AND RESULTS

Microembolic signal counts were monitored by transcranial Doppler sonography of both middle cerebral arteries under normobaria (normobaria 1), 2 subsequent periods of hyperbaria (2.5 and 1.75 bar), and a second period of normobaria (normobaria 2) in 15 patients with prosthetic heart valves. Each monitoring period lasted 30 minutes. Compression and decompression rates were 0.1 bar/min. Microembolic signal counts increased from 20 (12-78) at normobaria 1 to 79 (30-165) at 2.5 bar (P <.01 vs normobaria 1 and 2), decreased to 44 (18-128) at 1.75 bar (P <.01 vs normobaria 1 and 2.5 bar; P <.001 vs normobaria 2), and returned to 20 (8-96) at normobaria 2 (values are medians and 95% confidence intervals).

CONCLUSIONS

Our results strongly suggest that gaseous bubbles are underlying material for part of the microembolic signals detected in patients with prosthetic heart valves.

Fourteen year experience with the omnicarbon prosthetic heart valve

The Omnicarbon prosthetic valve was implanted in 168 patients (mean age, 53 years); 84 had aortic valve replacement (AVR), 57 had mitral valve replacement (MVR), and 27 had both aortic and mitral valve replacement (DVR). The mean follow-up period was 6.8 years, with a maximum of 13.7 years. Three patients (1.8%) were lost to follow-up. There were 4 (2.4%) early deaths and 26 late deaths. Survival at 10 years was 76% in the AVR and MVR groups, and 85% in the DVR group. Freedom from thromboembolism at 10 years was 94% in the AVR group, 80% in the MVR group, and 92% in the DVR group. Freedom from hemorrhagic complications at 10 years was 86% in the AVR group and 92% in the MVR group. At 10 years, 97% in the AVR group and 96% in the MVR group were free from endocarditis. One patient in the DVR group suffered a paravalvular leak. At 10 years, 97% in the AVR group and 95% in the MVR group had not needed reoperation. Elevation of the postoperative serum lactate dehydrogenase levels were acceptable in the three groups. In conclusion, the Omnicarbon prosthetic valve has shown excellent long-term clinical results.

Evolution of mechanical heart valves

The need for prosthetic heart valves was long recognized but seemed an impossible dream before 1952 when Dr Charles Hufnagel clinically introduced a ball valve that he placed into the descending thoracic aorta for treatment of aortic valvular insufficiency. Fulfillment of that dream became a reality with the advent of extracorporeal circulation in the early 1950s. Development of prosthetic heart valves involved the search for biologically compatible materials and hemologically tolerant designs. Success could not be achieved without the union of these two factors. As there was no satisfactory mechanism to scientifically achieve this goal, trial and error was the method of choice. The development of prosthetic heart valves became the purview of the cardiovascular surgeon who often collaborated with engineers. To distinguish one valve from another each prosthesis often became identified with the surgeon developer. The development of bioprostheses occurred later in the development of artificial heart valves and constitutes a separate subject not covered in this presentation.