Mechanical versus Bioprosthetic Aortic Valve Replacement in Patients Aged 50 to 70 Years

Background

This study compared the outcomes of surgical aortic valve replacement (AVR) in patients aged 50 to 70 years based on the type of prosthetic valve used.

Methods

We compared patients who underwent mechanical AVR to those who underwent bioprosthetic AVR at our institution between January 2000 and March 2019. Competing risk analysis and the inverse probability of treatment weighting (IPTW) method based on propensity score were employed for comparisons.

Results

A total of 1,580 patients (984 patients with mechanical AVR; 596 patients with bioprosthetic AVR) were enrolled. There was no significant difference in early mortality between the mechanical AVR and bioprosthetic AVR groups (0.9% vs. 1.7%, p=0.177). After IPTW adjustment, the risk of all-cause mortality was significantly higher in the bioprosthetic AVR group than in the mechanical AVR group (hazard ratio [HR], 1.39; 95% confidence interval [CI], 1.07-1.80; p=0.014). Competing risk analysis revealed lower risks of stroke (sub-distributional hazard ratio [sHR], 0.44; 95% CI, 0.28-0.67; p<0.001) and anticoagulation-related bleeding (sHR, 0.35; 95% CI, 0.23-0.53; p<0.001) in the bioprosthetic AVR group. Conversely, the risk of aortic valve (AV) reintervention was higher in the bioprosthetic AVR group (sHR, 6.14; 95% CI, 3.17-11.93; p<0.001).

Conclusion

Among patients aged 50 to 70 years who underwent surgical AVR, those receiving mechanical valves showed better survival than those with bioprosthetic valves. The mechanical AVR group exhibited a higher risk of stroke and anticoagulation-related bleeding, while the bioprosthetic AVR group showed a higher risk of AV reintervention.

Impact of explanted valve type on aortic valve reoperations: nationwide UK experience

OBJECTIVES

This nationwide retrospective cohort study assessed the impact of the explanted valve type on reoperative outcomes in aortic valve surgery within the UK over a 23-year period.

METHODS

Data were sourced from the National Institute for Cardiovascular Outcomes Research (NICOR) database. All patients undergoing first-time isolated reoperative aortic valve replacement between 1996 and 2019 in the UK were included. Concomitant procedures, homograft implantation or aortic root enlargement were excluded. Propensity score matching was utilized to compare outcomes and risk factors for in-hospital mortality was evaluated through multivariable logistic regression. Final model selection was conducted using Akaike Information Criterion through bootstrapping. The primary end point was in-hospital mortality, and secondary end points included postoperative morbidities.

RESULTS

Out of 2371 patients, 24.9% had mechanical and 75% had bioprosthetic valves implanted during the primary procedure. Propensity matched groups of 324 patients each, were compared. In-hospital mortality for mechanical and bioprosthetic valve explants was 7.1% and 5.9%, respectively (P = 0.632). On multivariable logistic regression analysis, valve type was not a risk factor for mortality [odds ratio (OR) 0.62, 95% confidence interval (CI) 0.37-1.05; P = 0.1]. Age (OR 1.03, 95% CI 1.01-1.05; P < 0.05), left ventricular ejection fraction (OR 1.62, 95% CI 1.08-2.42; P < 0.05), creatinine ≥ 200 mg/dl (OR 2.21, 95% CI 1.17-4.04; P < 0.05) and endocarditis (OR 2.66, 95% CI 1.71-4.14; P < 0.05) emerged as risk factors for mortality.

CONCLUSIONS

The type of valve initially implanted (mechanical or bioprosthetic) did not determine mortality. Instead, age, left ventricular ejection fraction, renal impairment and endocarditis were significant risk factors for in-hospital mortality.

Long-Term Outcomes of Mechanical Aortic Valve Replacement in Children

When the options of aortic valve repair or the Ross procedure are not feasible or have been exhausted, mechanical aortic valve replacement (AVR) may provide a reliable and structurally durable alternative, but with the limitations of long-term anticoagulation, thrombosis risk and lack of valve growth potential. In this article, we review the longitudinal outcomes of mechanical AVR in children in our institution and compare them to those recently reported by others. From 1978 to 2020, 62 patients underwent mechanical AVR at a median age of 12.4 years (interquartile range (IQR): 8.6-16.8 years). The most common underlying diagnoses were: conotruncal anomalies (40%, 25/62), congenital aortic stenosis (16%, 10/62), rheumatic valve disease (16%, 10/62), connective tissue disease (8.1%, 5/62) and infective endocarditis (6.5%, 4/62). Thirty-two patients (52%, 32/62) had at least 1 prior aortic valve surgery prior to mechanical AVR. Early death was 3.2% (2/62). Median follow-up was 14.4 years (IQR: 8.4-28.2 years). Kaplan-Meier survival was 96.8%, 91.9%, 86.3%, and 81.9% at 1, 5, 10, and 20 years. On competing risk analysis, the proportion of patients alive without aortic valve reoperation at 1, 5, 10, and 20 years was 95.2%, 87.0%, 75.5% and 55.4%, respectively, while the proportion of patients that had aortic valve reoperation (with death as a competing event) at 1, 5, 10, and 20 years was 1.6%, 4.9%, 12.8%, and 28.5%, respectively. In conclusion, when the options of aortic valve repair or the Ross procedure are not feasible in children, mechanical AVR is an alternative, yet the long-term rates of mortality and need for aortic valve reoperation are of concern.

Ross procedure versus pulmonary homograft versus mechanical valve versus bioprosthetic valve versus Ozaki procedure for surgical aortic valve replacement: a frequentist network meta-analysis

BACKGROUND

There has been a resurgence in interest regarding the Ross procedure due to recent publications detailing positive long-term outcomes. Conversely, surgical aortic valve replacement (SAVR) with a pulmonary homograft (PH), mechanical (MV), bioprosthetic (BV), or the Ozaki procedure each has its own technical advantages and disadvantages. Therefore, we performed a network meta-analysis (NMA) comparing other alternatives to Ross procedure.

METHODS

Medical databases were comprehensively searched for studies comparing the Ross procedure with AVR using a PH, MV, BV, or the Ozaki procedure. Outcomes were pooled as risk ratios (RR) with their 95% confidence intervals (95% CI).

RESULTS

A total of 7816 patients were pooled for our NMA from 24 studies. Compared to Ross procedure, both BV and MV were associated with significantly higher rates of 30-day mortality of RR (2.37, 95% CI 1.20-4.67) and (1.88 95% CI 1.04-3.40), respectively, with no significant difference regarding PH or Ozaki. However, only MV was associated with a higher risk of 30-day stroke (RR 8.42, 95% CI 1.57-45.23) with no significant difference in the other alternatives, as well as 30-day MI which showed no significant differences between any of the aortic conduits compared to the Ross procedure. Regarding 30-day major bleeding, MV was associated with a higher when compared to the Ross procedure RR (4.58, 95% CI 1.94-10.85), PH was associated with a lower risk of major bleeding with RR (0.35, 95% CI 0.17-0.71), and BV showed no significant difference. With a mean follow-up duration of 8.5 years compared to the Ross procedure, BV, PH, and MV were associated with a higher risk of long-term mortality with RR (1.89, 95% CI 1.38-2.58), (1.38, 95% CI 1.0-1.87), and (1.94, 95% CI 1.52-2.47), respectively, with the Ozaki procedure showed no significant difference. Regarding long-term stroke-with a mean of 6.3-year follow-up duration-there were no significant differences between any of the aortic conduits compared to the Ross procedure. Nevertheless, long-term need for reintervention-with a mean follow-up duration of 17.5 years-was significant of higher risk with both BV and PH with RR (3.28, 95% CI 1.21-8.84) and (2.42, 95% CI 1.05-5.58), respectively, compared to Ross procedure with MV and Ozaki having no significant difference.

CONCLUSIONS

The Ross procedure is a viable treatment option for patients undergoing SAVR, showing promising outcomes at short- and long-term follow-ups.

Readmissions After Surgical Aortic Valve Replacement: Influence of Prosthesis Type

INTRODUCTION

Prosthesis choice during aortic valve replacement (AVR) weighs lifelong anticoagulation with mechanical valves (M-AVR) against structural valve degeneration in bioprosthetic valves (B-AVR).

METHODS

The Nationwide Readmissions Database was queried to identify patients who underwent isolated surgical AVR between January 1, 2016 and December 31, 2018, stratifying by prothesis type. Propensity score matching was used to compare risk-adjusted outcomes. Readmission at 1 y was estimated with Kaplan-Meier (KM) analysis.

RESULTS

Patients (n = 109,744) who underwent AVR (90,574 B-AVR and 19,170 M-AVR) were included. B-AVR patients were older (median 68 versus 57 y; P < 0.001) and had more comorbidities (mean Elixhauser score: 11.8 versus 10.7; P < 0.001) compared to M-AVR patients. After matching (n = 36,951), there was no difference in age (58 versus 57 y; P = 0.6) and Elixhauser score (11.0 versus 10.8; P = 0.3). B-AVR patients had similar in-hospital mortality (2.3% versus 2.3%; P = 0.9) and cost (mean: $50,958 versus $51,200; P = 0.4) compared with M-AVR patients. However, B-AVR patients had shorter length of stay (8.3 versus 8.7 d; P < 0.001) and fewer readmissions at 30 d (10.3% versus 12.6%; P < 0.001) and 90 d (14.8% versus 17.8%; P < 0.001), and 1 y (P < 0.001, KM analysis). Patients undergoing B-AVR were less likely to be readmitted for bleeding or coagulopathy (5.7% versus 9.9%; P < 0.001) and effusions (9.1% versus 11.9%; P < 0.001).

CONCLUSIONS

B-AVR patients had similar early outcomes compared to M-AVR patients, but lower rates of readmission. Bleeding, coagulopathy, and effusions are drivers of excess readmissions in M-AVR patients. Readmission reduction strategies targeting bleeding and improved anticoagulation management are warranted in the first year following AVR.

Comprehensive collection of COVID-19 related prosthetic valve failure: a systematic review

Since the beginning of the SARS-CoV-2 (COVID-19) pandemic, correlation of venous thromboembolism (VTE) and COVID-19 infection has been well established. Increased inflammatory response in the setting of COVID-19 infection is associated with VTE and hypercoagulability. Venous and arterial thrombotic events in COVID-19 infection have been well documented; however, few cases have been reported involving cardiac valve prostheses. In this review, we present a total of eight cases involving COVID-19-related prosthetic valve thrombosis (PVT), as identified in a systematic review. These eight cases describe valve position (mitral versus aortic) and prosthesis type (bioprosthetic versus mechanical), and all cases demonstrate incidents of PVT associated with simultaneous or recent COVID-19 infection. None of these eight cases display obvious non-adherence to anticoagulation; five of the cases occurred greater than three years after the most recent valve replacement. Our review offers insights into PVT in COVID-19 infected patients including an indication for increased monitoring in the peri-infectious period. We explore valve thrombosis as a mechanism for prosthetic valve failure. We describe potential differences in antithrombotic strategies that may offer added antithrombotic protection during COVID-19 infection. With the growing population of valve replacement patients and recurring COVID-19 infection surges, it is imperative to explore relationships between COVID-19 and PVT.

The role of mechanical valves in the aortic position in the era of bioprostheses and TAVR: Evidence-based appraisal and focus on the On-X valve

Patients who need a prosthetic aortic heart valve may decide, working with their cardiologist and cardiac surgeon, among a variety of options: surgical or transcatheter approach, bioprosthetic or mechanical valve, or a Ross procedure if suitable to their age and anatomy. This review article examines the evidence for survival benefit with mechanical aortic valves, discusses bioprosthetic structural valve degeneration and its consequences, and considers the risks of redo aortic valve surgery or subsequent valve-in-valve (ViV) transcatheter intervention. It highlights the unique characteristics of the On-X aortic valve, including the US Food and Drug Administration approved and American College of Cardiology/American Heart Association guideline supported reduced anticoagulation target INR of 1.5 to 2.0, and discusses the PROACT Xa trial comparing apixaban vs warfarin anticoagulation. The choice of prosthetic valve should be individualized, carefully considering each patient's unique circumstances. In that context, the On-X aortic valve offers a potential lifetime solution without need for a repeat operation, while minimizing the risks of long-term anticoagulation. In an era of enthusiasm for bioprosthetic and transcatheter-based approaches, the option of a second-generation bileaflet mechanical valve with optimized hemodynamics-the On-X aortic valve-may well align with patient expectations.

On-X mitral valve leaflet embolization presenting as acute pulmonary oedema

Background

Structural valve failure in the form of leaflet fracture and embolization is an uncommon complication. Severe valve regurgitation with pulmonary oedema in a patient with a history of a prosthetic cardiac valve requires urgent diagnosis. An echocardiogram is essential in identifying the cause of valve failure.

Case presentation

We report a case of a 21-year-old male patient who presented with acute pulmonary oedema due to fracture and embolization of a leaflet of an On-X mitral valve four years post-implant. He underwent an emergency redo mitral valve replacement with a good outcome.

Conclusions

Structural valve failure with leaflet fracture and embolization is an extremely rare complication and may be fatal. Good clinical acumen is required for prompt diagnosis in any patient who presents with a circulatory collapse in the presence of a history of previous cardiac surgery. Once the diagnosis is made, the patient should undergo emergency redo valve replacement surgery.

A simple closure method for a mechanical aortic valve in left ventricular assist device implantation

Because a mechanical aortic valve is a contraindication for the implantation of left ventricular assist device, complicated additional procedures such as a replacement with a bioprosthesis and a closure of the left ventricular outflow tract are required to implant the device. Among such procedures, a sandwich plug technique using vascular clips is one of the simple and feasible procedures. However, this technique requires an off-label use of vascular clips within the aorta that could be associated with a risk of dislodgement and embolization. Thus, we developed a modified sandwich technique without using vascular clips, where the valve leaflets were fixed in the closed position using felt patches and sutures instead of vascular clips. This modified technique is a simple and secure method to close the mechanical aortic valve with the minimum use of artificial materials.

Prosthetic cardiac valves: history and review of cardiac prostheses clinically available in Japan

Recently developed prosthetic valves are reliable and essential for the treatment of valvular heart disease. The mechanical valve evolved remarkably following the introduction of pyrolite carbon material, which enabled the creation of a bileaflet form incorporated with a pivot mechanism. The improved durability of the biological valve is attributed mainly to the development of a tissue fixation process and anti-calcification treatments. However, optimal antithrombogenicity and durability have not yet been achieved for either prosthetic valve type. To select the most suitable prosthetic valve for each individual patient from among the many clinically available prosthetic valves, it is necessary to have a thorough understanding of the characteristics of each valve.

Predictors of survival in paediatric mitral valve replacement

OBJECTIVES

The aim of this study was to identify the predictors of death and of reintervention after mitral valve replacement (MVR) in children.

METHODS

A single-centre retrospective study was performed including 115 patients under the age of 18 undergoing MVR between 1982 and 2019. For all patients, the ratio of prosthetic valve size (diameter in mm) to weight (kg) at surgery was calculated and long-term result was assessed. The primary outcome was freedom from mitral valve (MV) re-replacement. The composite secondary outcome was freedom from death or transplant.

RESULTS

Fifty-four patients had a previous surgical attempt to MV repair. The median age at surgery was 5.5 years (interquartile range 1.21-9.87). Death/transplant-free survival was 77 ± 4% at 5 years and 72 ± 5% at 10 years. Univariate analysis showed a size/weight ratio higher than 2 and age <2 years as significant risk factors for death or transplant. Freedom from MV re-replacement at 5 and 10 years was 90 ± 3% and 72 ± 6%, respectively. Biological prosthesis implanted at first replacement (P = 0.007) and size/weight ratio higher than 2 (P = 0.048) were predictors of reoperation. Significant upsizing (P < 0.0001) of mitral prosthesis was observed at re-replacement.

CONCLUSIONS

MVR is a viable strategy in children with unrepairable MV disease. Mortality can be predicted based on size/weight ratio and age <2 years. MV re-replacement can be performed with low morbidity and mortality and a larger-size prosthesis can often be placed at the time of redo.

Propensity matched long-term analysis of mechanical versus stentless aortic valve replacement in the younger patient

OBJECTIVES

The choice of prosthesis for aortic valve replacement (AVR) in younger patients remains controversial. Stentless AVR was introduced 3 decades ago, with the aim of better haemodynamics and durability than stented xenografts. The objective of this analysis was to compare the long-term outcomes to mechanical prostheses in younger patients (age ≤60 years).

METHODS

All adult patients who underwent AVR due to aortic valve stenosis and/or insufficiency between 1993 and 2002 were identified. After the exclusion of patients with congenital heart defects, aortic dissections and Ross-procedures, 158 patients with stentless valves and 226 patients with bi-leaflet mechanical valves were finally included in this analysis. Sixty-six patient pairs could be included in a propensity matched analysis. Mortality and morbidity including stroke, bleeding, endocarditis and reoperation were analysed.

RESULTS

Group baseline characteristics and operative data did not differ significantly after propensity matching. Hospital mortality was 0.0% in the stentless and 1.5% in the mechanical group. Total patient years/median follow-up was 2029.1/15.4 years (completeness: 100.0%, range: 0-25 years). After 20 years, actuarial survival was 47.0 ± 6.4% in the stentless and 53.3 ± 6.6% in mechanical group (P = 0.69). Bleeding, endocarditis and stroke occurred rarely and did not differ significantly between groups. After 20 years, actuarial overall freedom-from-reoperation was 45.1 ± 8.2% in the stentless group and 90.4 ± 4.1% in the mechanical group (P < 0.001). Hospital mortality while reoperation was 7.4% in the stentless group and 0% in the mechanical group (P = 1.0).

CONCLUSIONS

Long-term morbidity and mortality of stentless and mechanical aortic valves were statistically not different besides a significantly higher reoperation rate after stentless AVR combined with a probably higher risk of in-hospital mortality. Thus, mechanical AVR should remain the procedure of choice in younger patients.

Effect of Aortic Valve Type on Patients Who Undergo Type A Aortic Dissection Repair

Aortic valve replacement (AVR) is common in the setting of type A aortic dissection (TAAD) repair. Here, we evaluated the association between prosthesis choice and patient outcomes in an international patient cohort. We reviewed data from the International Registry of Acute Aortic Dissection (IRAD) interventional cohort to examine the relationship between valve choice and short- and mid-term patient outcomes. Between January 1996 and March 2016, 1290 surgically treated patients with TAAD were entered into the IRAD interventional cohort. Of those, 364 patients undergoing TAAD repair underwent aortic valve replacement (AVR; mean age, 57 years). The mechanical valve cohort consisted of 189 patients, of which 151 (79.9%) had a root replacement. The nonmechanical valve cohort consisted of 5 patients who received homografts and 160 patients who received a biologic AVR, with a total of 118 (71.5%) patients who underwent root replacements. The mean follow-up time was 2.92 ± 1.75 years overall (2.46 ± 1.69 years for the mechanical valve cohort and 3.48 ± 1.8 years for the nonmechanical valve cohort). After propensity matching, Kaplan-Meier estimates of 4-year survival rates after surgery were 64.8% in the mechanical valve group compared with 74.7% in the nonmechanical valve group (p = 0.921). A stratified Cox model for 4-year mortality showed no difference in hazard between valve types after adjusting for the propensity score (p = 0.854). A biologic valve is a reasonable option in patients with TAAD who require AVR. Although this option avoids the potential risks of anticoagulation, long-term follow up is necessary to assess the effect of reoperations or transcatheter interventions for structural valve degeneration.

Outcomes related to anticoagulation management for mechanical valve replacements

Background

This study evaluates anticoagulation management and its impact on longitudinal clinical outcomes in patients undergoing mechanical valve replacement.

Methods

Patients undergoing mechanical mitral valve replacement (MVR) or aortic valve replacement (AVR) from 2010–2018 at a single center were included. Patients were stratified into therapeutic and non-therapeutic anticoagulation groups based on the median percentage of international normalized ratio (INR) values within the reference range (2.0–3.0 for AVR, 2.5–3.5 for MVR) during the first post-operative year. Using Cox regression analysis, comorbidity-adjusted survival and freedom from adverse events were compared.

Results

Six hundred and fifty-one patients underwent mechanical valve replacement (166 MVR, 485 AVR). Comorbidity-adjusted survival was similar in the MVR and AVR cohorts (P=0.23). There was a median of 27 [interquartile range (IQR): 14–42] INRs drawn per patient in the first post-operative year. The median percentage of INRs within the reference values during the first post-operative year was 42.85% (IQR: 30.77–53.95%), with the majority of non-therapeutic INRs being subtherapeutic (34.51%; n=6,864). There were no significant differences in adjusted survival between the therapeutic and non-therapeutic groups [hazard ratio (HR): 1.12, P=0.73]. Within the first post-operative year, there were no significant differences in stroke, major bleeding, peripheral non-stroke arterial thromboembolism, and readmission for intravenous heparin in the therapeutic and non-therapeutic groups.

Conclusions

Taking into account relevant comorbidities and valve type, patients with a larger proportion of non-therapeutic INRs during the first post-operative year demonstrated no difference in longitudinal clinical outcomes. Further research into more standardized INR monitoring and potentially expanded INR target ranges for patients undergoing mechanical valve replacement is warranted.

Evaluation of on-line solid-phase extraction capillary electrophoresis-mass spectrometry with a nanoliter valve for the analysis of peptide biomarkers

On-line solid-phase extraction capillary electrophoresis-mass spectrometry (SPE-CE-MS) is a powerful technique for high throughput sample clean-up and analyte preconcentration, separation, detection, and characterization. The most typical design due to its simplicity and low cost is unidirectional SPE-CE-MS. However, in this configuration, the sample volumes introduced by pressure depend on the dimensions of the separation capillary and some matrix components could be irreversibly adsorbed in its inner walls. Furthermore, in many cases, the requirements of on-line preconcentration are incompatible with the background electrolyte necessary for an efficient separation and sensitive MS detection. Here, we present SPE-CE-MS with a nanoliter valve (nvSPE-CE-MS) to overcome these drawbacks while keeping the design simple. The nvSPE-CE-MS system is operated with a single CE instrument and two capillaries for independent and orthogonal SPE preconcentration and CE separation, which are interfaced through an external and electrically isolated valve with a 20 nL sample loop. The instrumental setup is proved for the analysis of opioid and amyloid beta peptide biomarkers in standards and plasma samples. NvSPE-CE-MS allowed decreasing the limits of detection (LODs) 200 times with regard to CE-MS. Compared to unidirectional SPE-CE-MS, peak efficiencies were better and repeatabilities similar, but total analysis times longer and LODs for standards slightly higher due to the heart-cut operation and the limited volume of the valve loop. This small difference on the LODs for standards was compensated for plasma samples by the improved tolerance of nvSPE-CE-MS to complex sample matrices. In view of these results, the presented setup can be regarded as a promising versatile alternative to avoid complicated matrix samples entering the separation capillary in SPE-CE-MS.

Ultraslow thrombolytic therapy in stuck mechanical aortic valve, case report, and review of the literature

Background

Stuck mechanical heart valves had a debate about the management plan. There is debate regarding the type, dose, and rate of administration of various thrombolytic agents. We report a case with successful thrombolysis using an ultraslow regimen.

Case summary

A 43-year-old female with a history of aortic valve (AV) and mitral valve replacement (bi-leaflet metallic valves), and tricuspid valve repair (MINI band) at October 2017. Physical examination showed normal metallic first heart sound and weak metallic second heart sound. Laboratory investigations were normal except low INR, hematocrit, and hemoglobin level (9 gm/L due to iron deficiency anemia). Transthoracic echocardiogram (TTE) and Transoesophageal echocardiogram (TEE) confirmed stuck aortic valve leaflet, with a high mean pressure gradient across prosthetic AV (34 mmHg). The mechanical mitral valve was working well. Fluoroscopy showed stuck one of the AV leaflets in a closed position. The treating physician decided to give her the chance for thrombolytic therapy. This case was treated with ultraslow thrombolytic therapy (Alteplase, 1 mg, every hour) with follow up transthoracic echocardiogram every 24 h to check the pressure gradient on the AV. She was young, asymptomatic, and hemodynamically stable. After 48 h of Alteplase, the stuck leaflet was released. The mean pressure gradient dropped to 16 mmHg.

Discussion

Ultraslow thrombolytic regimen advised to be tried in stuck mechanical valves and hemodynamically stable patients.

Safety of low intensity oral anticoagulant therapy in patients with bileaflet mechanical aortic valve prosthesis: A propensity weighted study

BACKGROUND

Scarce data are available on the long-term outcomes of different regimens of oral anticoagulation in an all comer population of patients undergoing aortic valve replacement with a bileaflet mechanical heart valve.

METHODS

Outcomes of 88 patients discharged with a target INR of 2.0 (LOW-INR) were compared to 147 contemporary patients who have been recommended a target INR of 2.5 (CONV). Primary outcome was the composite of any thromboembolic or haemorrhagic events. Secondary outcomes were the individual components of the primary outcome, cardiovascular mortality and stroke. To reduce selection bias, a propensity weighted analysis was performed.

RESULTS

After inverse probability of treatment weighting, the primary endpoint occurred in 0.7% of patient in the LOW-INR group and in 7.0% in the CONV group (p = .0255). Linearized event rate were significantly lower in the LOW-INR group (primary endpoint: rate difference - 12.0 per 1000 patient/years, p = .0052; haemorrhage: -5.8 per 1000 patient/years, p = .0330; neurological events: -7.6 per 1000 patient/years, p = .0140). Conventional target INR was associated with an increased hazard of the composite endpoint (HR 11.193, 95% CI 1.424-88.003, p = .0217).

CONCLUSIONS

Lowering the intensity of oral anticoagulation resulted in a relevant clinical benefit of reduced rates of haemorrhagic and neurological adverse events in the mid-term follow-up. This report confirms the safety profile of the low INR regimen in an all comer population undergoing aortic valve replacement with an Abbott mechanical valve.

Impact of needle-free connectors compared with 3-way stopcocks on catheter-related bloodstream infection rates: A meta-analysis

BACKGROUND

Needle-free connectors (NFCs) were introduced to eliminate the use of needles in intravascular catheters, and their newest generations were designed to improve patient safety and reduce catheter-related bloodstream infection (CRBSI) risks. The aim of this meta-analysis was to compare NFCs with 3-way stopcocks (3WSCs) and their effects on CRBSI rates.

METHODS

A meta-analysis was conducted using a research protocol consistent with the PRISMA statement for reporting meta-analyses. The Cochrane Database of Systematic Reviews and MEDLINE were searched for relevant randomized studies published from January 2000 to September 2018.

RESULTS

We identified and selected for the meta-analysis 8 studies comparing CRBSI rates (according to the Centers for Disease Control and Prevention's National Healthcare Safety Network definition) associated with NFCs utilizing negative-displacement, neutral-displacement, or positive-displacement devices with rates for 3WSCs. Relative risk was 0.53 with a 95% CI of 0.28 to 1.00, and the relative difference was -0.018 with a 95% CI of -0.039 to 0.004.

CONCLUSIONS

CRBSI risk was statistically higher for 3WSCs compared to NFCs.

Mechanical versus biological valve prosthesis for surgical aortic valve replacement in patients with infective endocarditis

OBJECTIVES

The optimal choice of valve prosthesis in surgical aortic valve replacement for infective endocarditis (IE) is controversial. We studied outcomes after mechanical versus biological prosthetic valve surgical aortic valve replacement in IE patients.

METHODS

All patients with native-valve IE aged 16-70 years undergoing mechanical or biological surgical aortic valve replacement in Finland, between 2004 and 2014, were retrospectively studied (n = 213). Outcomes were all-cause mortality, ischaemic stroke, major bleeding and aortic valve reoperation at 1 year and 5 years. Results were adjusted for baseline features (age, sex, comorbidity burden, atrial fibrillation, valvular stenosis, concomitant coronary artery bypass grafting, extension, urgency, year and centre of operation). Median follow-up was 5 years.

RESULTS

The 5-year mortality rate was 19.0% with mechanical prostheses and 34.8% with biological prostheses [hazard ratio (HR) 0.47, 95% confidence interval (CI) 0.23-0.92; P = 0.03]. Ischaemic stroke rates were 8.3% with mechanical prostheses and 16.8% with biological prostheses at 5 years (HR 0.21, CI 0.06-0.79; P = 0.01). Results were comparable in patients aged 16-59 and 60-70 years (interaction P = 0.84). Major bleeding within 5 years was similar between mechanical (11.3%) and biological valve (13.4%) groups (P = 0.95) with comparable rates of both gastrointestinal and intracranial bleeds. Reoperation rates at 5 years were 5.0% for mechanical prostheses and 9.2% for biological prostheses (P = 0.14). The 1-year ischaemic stroke rate was lower with mechanical prostheses (3.6% vs 11.6%, P =0.03), whereas mortality, major bleeding and reoperation rates were similar between groups.

CONCLUSIONS

The use of mechanical aortic valve is associated with lower mid-term mortality compared to biological prosthesis in patients with native-valve IE aged ≤70 years. Our results do not support the routine choice of a biological aortic valve prosthesis in this patient group.

Vector Flow Imaging of the Ascending Aorta in Patients with Tricuspid and Bicuspid Aortic Valve Stenosis Treated with Biological and Mechanical Implants

Aortic valve stenosis (AS) is treated with biological prostheses (BPs) and mechanical prostheses (MPs). Vector flow imaging (VFI), an angle-independent ultrasound method, can quantify flow complexity (vector concentration (VC)) and secondary rotation (SR). Ten patients (mean age: 70.7 y) with tricuspid AS scheduled for BPs, 10 patients (mean age: 56.2 y) with bicuspid AS scheduled for MPs and 10 patients (mean age: 63.9 y) with normal aortic valves were scanned intra-operatively on the ascending aorta with VFI and conventional spectral Doppler. Bicuspid AS (peak systolic velocity (PSV): 380.9 cm/s, SR: 16.7 Hz, VC: 0.21) had more complex flow (p < 0.02) than tricuspid AS (PSV: 346.1 cm/s, SR: 17.1 Hz, VC: 0.33). Both groups had more complex and faster flow (p < 0.0001) than normal aortic valve patients (PSV: 124.0 cm/s, SR: 4.3 Hz, VC: 0.79). VC (r = 0.87) and SR (r = 0.89) correlated to PSV. After surgery, flow parameters changed (p < 0.0001) for patients with MPs (PSV: 250.4 cm/s, SR: 9.8 Hz, VC: 0.54) and BPs (PSV: 232.4 cm/s, SR: 12.5 Hz, VC: 0.61), with MPs having slower SR (p < 0.01). None of the implants had normal flow (p < 0.0001). In conclusion, VFI can provide new flow parameters for AS and implant assessment.

Long-term outcome after mitral valve replacement using biological versus mechanical valves

BACKGROUND

This study compared long-term outcomes of biological and mechanical mitral valve replacement (MVR) in patients requiring replacement of the mitral valve where repair was not feasible.

METHODS

A single-centre registry of patients receiving MVR between 2005 and 2015 was established. Thirty-day mortality and long-term outcomes were analysed and compared.

RESULTS

Three hundred twenty four patients underwent MVR (265 biological; 59 mechanical valves). Patients receiving biological valves were older (p < 0.001), had a higher log EuroSCORE (p < 0.001) and received less minimally invasive surgery (p < 0.001). Immediate procedural mortality was 1.9%, which only occurred in the biological valve group. At 30 days, 9.0% of patients had died, 4.0% experienced stroke, 8.0% received a pacemaker and 10.5% suffered an acute renal failure. The rate of re-thoracotomy (14.2%) was lower in the biological (12.5%) than in the mechanical valve group (22.0%; adjOR 0.45 [0.20-1.00]; p = 0.050). Frequent long-term complications were stroke (9.2%) and bleeding (4.8%), with bleeding complications being higher in the mechanical valve group (p = 0.009). During the follow-up period biological valves showed a numerically higher survival rate during the first years, which shifted after 3 years in favour of mechanical valves. At 10 years, survival rates were 62.4% vs. 77.1% in the biological and mechanical valve groups (p = 0.769). Hazard ratio after adjustment was 0.833 (95% CI 0.430-1.615).

CONCLUSION

These data confirm that mechanical valve implantation is associated with an increased risk of bleeding. While there was a potential survival benefit during the first years after surgery for patients receiving a biological valves the difference became insignificant after a follow-up of 10 years.

Late prosthetic valve endocarditis with Mycobacterium tuberculosis after the Bentall procedure

Background

Prosthetic valve endocarditis (PVE) is a rare but severe complication of valve replacement surgery, with an incidence rate of 0.3–1.2% per patient-year. At present, staphylococci are the predominant causative microorganism of PVE. Herein, we report a confirmed case of late PVE in a mechanical aortic valve caused by Mycobacterium tuberculosis.

Case presentation

A 32-year-old immunocompetent man with recurrent fever and 5-kg weight loss had a history of having undergone the Bentall procedure due to congenital heart disease. Nine years after the operation, he developed a paravalvular abscess in the mechanical aortic valve, presented with evidence of pulmonary tuberculosis on CT scan and was diagnosed with tuberculous endocarditis. This case report highlights a rare and non-negligible example of tuberculous endocarditis involving a mechanical valve.

Conclusions

Tuberculous PVE should be considered in patients with a history of valve replacement, recurrent fever, unexplained weight loss, pulmonary tuberculosis and meaningful valvular findings on echocardiogram.

Diagnostic challenges in infective endocarditis: is PET/CT the solution?

PURPOSE

Despite developments in both imaging and microbiological techniques, the final diagnosis of IE often remains challenging. In this single-center cohort study, we aimed to identify the specific indications for request of ¹⁸F-FDG-PET/CT in clinical practice and to evaluate the diagnostic benefit of this nuclear imaging technique.

METHODS

A total of 235 patients with possible (n = 43) or definite (n = 192) IE according to the revised Duke criteria were prospectively studied from July 2013 until December 2016. Echocardiography was generally used as the primary cardiac imaging technique. All patients were treated by a multidisciplinary Endocarditis Team. Diagnostics with ¹⁸F-FDG-PET/CT were undertaken on request by at least one member of the multidisciplinary team when overall diagnostics were inconclusive.

RESULTS

In 20 patients, ¹⁸F-FDG-PET/CT scan was performed for additional diagnostic evaluation. Hereof, 15 patients had a history of implanted cardiac prosthetic material. In six patients with definite IE, the use of ¹⁸F-FDG-PET/CT was helpful for further clarification of the diagnosis. In one patient with possible IE, the diagnosis could be reclassified to definite IE. In addition, one case of vertebral osteomyelitis as well as upper and lower leg abscesses and knee empyema were detectable as extracardiac foci. Furthermore, ¹⁸F-FDG-PET/CT leads to a modification of the management in five patients.

CONCLUSION

Our findings support the utility of ¹⁸F-FDG-PET/CT as an adjunctive diagnostic tool especially in the evaluation of prosthetic valve-/cardiac device-related IE and for the detection of extracardiac foci in some cases. However, due to remaining limitations also of this imaging technique, a multidisciplinary clinical evaluation still remains the essential basis for the diagnostic assessment.

Heart-cut nano-LC-CZE-MS for the characterization of proteins on the intact level

Multidimensional separation techniques play an increasingly important role in separation science, especially for the analysis of complex samples such as proteins. The combination of reversed-phase liquid chromatography in the nanoscale and CZE is especially beneficial due to their nearly orthogonal separation mechanism and well-suited geometries/dimensions. Here, a heart-cut nano-LC-CZE-MS setup was developed utilizing for the first time a mechanical 4-port valve as LC-CE interface. A model protein mixture containing four different protein species was first separated by nano LC followed by a heart-cut transfer of individual LC peaks and subsequent CZE-MS analysis. In the CZE dimension, various glycoforms of one protein species were separated. Improved separation capabilities were achieved compared to the 1D methods, which was exemplarily shown for ribonuclease B and its different glycosylated forms. LODs in the lower μg/mL range were determined, which are considerably lower compared to traditional CZE-MS. In addition, this study represents the first application of an LC-CE-MS system for intact protein analysis. The nano-LC-CZE-MS system is expected to be applicable to various other analytical challenges.

Re-do mitral valve replacement for a bioprosthetic valve with central transvalvular leakage in a patient with ischemic cardiomyopathy: a case report

Transvalvular leakage (TVL) of a prosthetic heart valve is not negligible regurgitant flow in patients with critically low contractile function. Although the opening function of prosthetic valves has been reported, its closing function is not well understood. A man in his 70 s had a history of mitral valve replacement (MVR) with a Magna Mitral® valve for ischemic mitral valve regurgitation. He presented with dyspnea 2 years postoperatively. Echocardiography showed moderate TVL. The pulmonary capillary wedge pressure and cardiac index were 37 mmHg and 1.65 L/min/m², respectively. Because we considered his TVL relevant, we performed re-do MVR with a mechanical valve and papillary muscle approximation and suspension ("papillary muscle tugging approximation"). His cardiac function improved postoperatively; he was discharged with New York Heart Association class I. For MVR in patients with critically low contractile function, prosthetic valves, such as mechanical valves, with small TVL are recommended.

A compact solvent extraction based 99Mo/99mTc generator for hospital radiopharmacy

A compact and portable ⁹⁹Mo-^99 mTc generator based on solvent-extraction, mimic to the conventional ⁹⁹Mo-^99 mTc alumina column generator is much-needed commodity for use in hospital radiopharmacy setup. The present study includes the development of a portable, simple and low cost ⁹⁹Mo/^99 mTc-generator based on MEK solvent extraction technique to obtain a very high concentration of no-carrier added (nca) ^99 mTc solution, where low specific activity ⁹⁹Mo source is obtained through ⁹⁸Mo(n, γ)⁹⁹Mo reaction in a research reactor. The unit is intended for operation under the conditions of medical radiological laboratories. Technical trials showed that the mean time of preparation of sodium [^99mTc] pertechnetate radiopharmaceutical did not exceed 15 min. The quality and yield of ^99 mTc-pertechnetate is upto the mark for formulation of radiopharmaceuticals.

[Initial experience of catheter ablation of ventricular tachycardia originate from endocardium via direct ventricle puncture access in patients underwent mechanical valve implantation]

Objective: To evaluate the results of catheter ablation of ventricular tachycardia (VT) via direct ventricle puncture access in patients without traditional approach. Methods: Two idiopathic left fasicular VT patients with mechanical aortic and mitrial valve repalcement and 1 patient with right ventricular originated VT post mechanical tricuspid valve repalcement from March 2010 to July 2012 in Fuwai hospital were enrolled in this study. For left fasicular VT patients, catheter ablation was performed using transapical left ventricular access via minithoracotomy. For the patient with right ventricular originated VT, catheter ablation was performed via percutaneous right ventricle puncture at xiphoid. Abaltion was guided under EnSite NavX mapping system. The feasibility of VT ablation via direct ventricle puncture access and long-term VT recurrence were investigated. Results: Catheter ablation was successful in all patients, and all clinical VTs were eliminated. The procedure time was 53, 62 and 74 minutes respectively with radiation time 11, 16 and 20 minutes. The ablation time was 130, 170 and 240 seconds individually. No procedure related complication occurred. After a follow-up time of 76, 55 and 82 months respectively, no VT recurrence was found in patients with left fasicular VT. New-onset VT with different morphology with previous VT was recorded in the patient with right ventricular originated VT, subcutaneous implantable defibrillator was implanted finally in this patient. Conclusions: For patients with endocardial origined ventricular arrhythmias which could not be ablated via traditional approaches, direct ventricle puncture access with hybrid techniques provides a new approach foreliminating VTs in these patients.

Current status of cardiovascular surgery in Japan, 2013 and 2014: A report based on the Japan Cardiovascular Surgery Database. 4. Valvular heart surgery

Data from the Japan cardiovascular surgery database from 2013 to 2014 were analyzed to demonstrate the mortality rate and choice of surgical procedures, especially concerning the selection of valve prosthesis for each valve position and patient age group, and the effects of preoperative complications on mortality and prosthetic valve selection. The proportion of each surgical procedure was compared for each patient age in the aortic, mitral, and tricuspid positions. The proportion of mechanical valve prostheses was 23.1, 40.5, and 11.4% in the aortic, mitral, and tricuspid positions, respectively, and was higher in hemodialysis than in non-hemodialysis patients. The operative mortality rate was 4.3, 11.7, 15.8, and 5.6% in all cases, hemodialysis patients, patients with liver dysfunction, and patients with atrial fibrillation and flutter, respectively, after Aaortic valve replacement, and 4.0, 14.4, 11.2, and 4.1%, respectively, in each group listed above after mitral valve surgery. These results clarify the current status of cardiac valvular surgery in Japan.

Mechanical aortic valve without anticoagulation for 33 years in a Yemeni man: a case report

BACKGROUND

Mechanical prosthetic heart valves have been used for many decades to replace damaged native valves. Guidelines mandate the use of anticoagulant therapy in patients with mechanical prosthetic valves of any type, irrespective of the position in the heart. The rationale for this is to prevent valve thrombosis and thromboembolic complications without increasing the risk of excess bleeding. We report a case involving a patient with a functioning aortic mechanical valve without any anticoagulation therapy for 33 years.

CASE PRESENTATION

A 46-year-old Yemeni man had an aortic valve replacement, using a St Jude Medical mechanical valve, 33 years ago due to aortic regurgitation grade III-IV of his native valve as a result of rheumatic heart disease. His anticoagulant therapy of Syncumar (acenocoumarol which is a derivative of coumarin) was discontinued 4 months after surgery, and he was sustained on aspirin and digoxin. He presented to our cardiac clinic 33 years later with palpitations, which had started 2 weeks previously. On clinical examination, his condition was fair with a New York Heart Association functional classification of I. He was in sinus rhythm and had normal heart size, as shown on chest X-ray. Echocardiography revealed normal heart chamber dimensions and normal left ventricular systolic and diastolic function. His mean transaortic gradient was 12.58 mmHg and the calculated aortic valve area was 1.44 cm(2). He was started on anticoagulant therapy.

CONCLUSIONS

Only a few cases of well-functioning mechanical valves without the use of anticoagulant therapy for many years have been reported. Our patient is one such case who used only aspirin for 33 years. Further research is needed to understand the interpersonal variations and other unexplored factors in anticoagulant therapy for patients with mechanical prosthetic heart valves.

Timing of vitamin K antagonist re-initiation following intracranial hemorrhage in mechanical heart valves: Systematic review and meta-analysis

BACKGROUND

While evidence supports resumption of vitamin K antagonists (VKAs) among mechanical heart valve (MHV) patients presenting with anticoagulant-associated intracranial hemorrhage (ICH), ideal timing of resumption is uncertain.

OBJECTIVE

To determine the optimal timing of VKA re-initiation and its associated clinical outcomes.

METHODS

We performed a systematic review and a meta-analysis of studies published from January 1950 to August 2015. We extracted data on the location of initial ICH, use of cranial surgery, presence of atrial fibrillation, MHV type and position, number of MHVs, and timing of VKA resumption. Outcomes including valve thrombosis, thromboembolic events or ICH recurrence were recorded. Meta-regression analysis was conducting with controlling for covariates. We calculated absolute risks, and assessed the effect of anticoagulant resumption timing on ICH recurrence.

RESULTS

23 case-series and case-reports were identified. Overall ICH recurrence was 13% (95% confidence interval [CI], 7%-25%), while valve thrombosis and ischemic strokes occurred at 7% (95% CI, 3%-17%) and 12% (95% CI, 5%-23%) respectively. A trend towards lower ICH recurrence was observed with delayed VKA resumption (slope estimate -0.2154, p=0.10). Recurrence rate ranged from 50% with VKA resumption at 3days to 0% with resumption at 16days.

CONCLUSION

Among patients with MHV, there is inadequate data to suggest an optimal timing of VKA re-initiation following an ICH, though delayed restart appears to be protective against recurrence but is associated with higher risk of thrombosis. Our analysis suggests 4-7days might be an ideal time with least risk of thrombosis or ICH recurrence.

Heart valve health, disease, replacement, and repair: a 25-year cardiovascular pathology perspective

The past several decades have witnessed major advances in the understanding of the structure, function, and biology of native valves and the pathobiology and clinical management of valvular heart disease. These improvements have enabled earlier and more precise diagnosis, assessment of the proper timing of surgical and interventional procedures, improved prosthetic and biologic valve replacements and repairs, recognition of postoperative complications and their management, and the introduction of minimally invasive approaches that have enabled definitive and durable treatment for patients who were previously considered inoperable. This review summarizes the current state of our understanding of the mechanisms of heart valve health and disease arrived at through innovative research on the cell and molecular biology of valves, clinical and pathological features of the most frequent intrinsic structural diseases that affect the valves, and the status and pathological considerations in the technological advances in valvular surgery and interventions. The contributions of many cardiovascular pathologists and other scientists, engineers, and clinicians are emphasized, and potentially fruitful areas for research are highlighted.

Extraction of a trapped pacemaker lead in a pacemaker-dependent patient

A 47-year-old female with a dual chamber pacemaker was referred to our institution for transvenous lead removal because of suspected pocket infection. The history of this patient started in 2002 with a tricuspid valve endocarditis. Therefore, the patient had tricuspid valve repair that yielded a poor outcome. The patient received biological tricuspid valve in 2006. Due to postoperative total atrioventricular-block a DDDR device was implanted. The biological valve degenerated and thus was replaced by a mechanical one in 2014. During this valve implantation the atrial lead was removed and the ventricular lead was trapped by the mechanical valve between the native tricuspid valve annulus of the right ventricle and the outer ring of the mechanical valve. Three months after the last revision the patient developed signs of inflammation. The pocket was opened and a swab test proved positive for Staphylococcus epidermidis. After disinfection with iodine solution the pacemaker was placed under the pectoralis muscle. However, during the following 3 months the patient suffered from swelling over the pacemaker pocket and severe pain. In awareness of the previous history and the clinical symptoms we decided to implant a new pacemaker system on the left side and explant the infected system on the right side. <Learning objective: Pocket infections always require system explantation. Simultaneous explantation of an infected system and implantation of a new system within the same session is not recommended but was necessary in this case. Even complex lead extraction like this one can be successfully performed applying the appropriate tools (locking stylet, Evolution device, Cook Intravascular Inc., Leechburg, PA, USA).>.

A reoperation of thrombosed On-X valve detected by multidetector-row computed tomography

A 62-year-old female patient underwent mitral valve replacement with a 31/33-mm On-X valve for ischemic mitral valve regurgitation. Three months later, transthoracic echocardiography incidentally showed a blocked leaflet with 6 mmHg of mean pressure gradient and 2.4 cm(2) of mitral valve orifice area. Transesophageal echocardiography could not detect thrombus. Electrocardiographically gated multidetector-row computed tomography (MDCT) clearly demonstrated a blocked leaflet in the close position and thrombus (2 cm in length, 0.4 cm(2) in area) attached onto the atrial aspect of the leaflet. These findings observed by MDCT were confirmed at reoperation. MDCT was useful diagnostic method for visualizing prosthetic valve thrombosis.

Comparison of central line-associated bloodstream infection rates when changing to a zero fluid displacement intravenous needleless connector in acute care settings

This was a multicenter, quasiexperimental, 140-month, acute care study comparing central line-associated bloodstream infection rates associated with positive or negative intravenous connectors to a zero fluid displacement connector. A decrease in central line-associated bloodstream infections was found after changing from either negative or positive intravenous connectors to the zero fluid displacement connector (P = .004) with total cost savings of over $3 million.

Mechanical valve dysfunction in yemen

Background:

Rheumatic heart disease is the most common cardiac disease in Yemen. It is associated with high morbidity and mortality. Valve replacement is the most common open heart surgery procedure in our cardiac center. The use of mechanical valves remains burdened with serious complications such as thrombosis. Valve thrombosis is still associated with high mortality^] The reported mortality rate of the redo operation ranges from 8 to 20% and up to 37-54% in critically ill patients.

Objective:

The aim of the present study was to investigate mechanical valve obstruction among Yemeni patients.

Patients and Methods:

Between January 2003 and April 2007, 2794 patients underwent prosthetic valve replacement in our center, Al-Thawra Hospital. Of those patients, 129 (4.6%) underwent reoperation for te obstructive mechanical valve. Patients with clinical suspicion of prosthetic valve obstruction (PVO) were admitted emergently to the CCU and the diagnosis was confirmed with echocardiography. All patients had heart failure; 95% of them were in NYHA class IV. All were transferred directly from the CCU to the operating room. The mean age was 34.8 ± 13.4 years. Two patients received preoperative thrombolytic therapy that was not successful. Obstruction involved the mitral valve prosthesis in 47 (36.4%); the aortic prosthesis in 16 (12.4%) patients; both valves in 21 (16.3%) patients; mitral valve replacement with tricuspid valve repair in 22(17%); double valve replacement with tricuspid valve repair in 1 (0.8%); redo mitral valve replacement with aortic valve cleaning in 7 (5.4%) cases; aortic valve cleaning in 5 (3.9%) patients; mitral valve cleaning in 5 (3.9%); and 5 (3.9%) patients had redo mitral with aortic replacement.

Results:

The operations were performed urgently. The etiology of the obstruction was thrombus in 111 (86%), pannus formation in 4 (3%), pannus and thrombus in 6 (4.8%), vegetation in 7 (5.4%) patients, and interposition of suturing materials in 1 (0.8%) patient. The in- hospital mortality was 23/129 (17.8%).

Conclusion:

The incidence of prosthetic valve obstruction remains high in Yemen. The vast majority of the patients who are referred to our hospital come from remote provinces in the country where regular INR measurement is not readily available. For those who are living in areas without good medical care, certain measures are necessary to avoid this disastrous complication: (1) good patient education, (2) free INR testing and free anticoagulant drugs such as warfarin; and (3) use of tissue rather than mechanical valves.