Mitral Annular Disjunction: Clinical Implications and Surgical Considerations.

Mitral annular disjunction is a cardiac structural abnormality characterized by the distinct separation between the top of the left ventricular myocardium and the mitral annulus supporting the posterior mitral leaflet occurring during systole. It has recently gained wide attention due to the increasing recognition of the link between mitral annular disjunction and arrhythmogenic mitral valve prolapse, particularly, with the increased risks of ventricular arrhythmias resulting in sudden cardiac death. This review has summarized the recent progress in the diagnostic modalities, clinical implications of mitral annular disjunction, and its specific surgical considerations.

Isolated Tricuspid Valve Replacement for Infective Endocarditis.

Background: Existing data regarding isolated tricuspid valve replacement for primary tricuspid valve disease such as infective endocarditis (IE) are limited. The aim of this study was to review our experience of isolated tricuspid valve replacement for IE. Methods: A retrospective review was performed to evaluate the perioperative and long-term outcomes of patients undergoing isolated tricuspid valve replacement for IE at our tertiary referral center between January 2000 and December 2014. Surgical outcomes were reviewed to include survival and postoperative complications. Results: Seven patients underwent isolated tricuspid valve replacement for IE during the study period. Mean age was 41 ± 14 years with six (86%) males. Six patients (86%) were intravenous drug users. Five patients (71%) presented with septic emboli to the lungs. Five patients (71%) had active endocarditis at the time of surgery. The indications for surgery were heart failure in three patients (43%), persistent sepsis in three patients (43%) and both in one patient (14%). Methicillin-sensitive Staphylococcus aureus was the most common infective organism, isolated in five patients (71%). There were no in-hospital mortalities or permanent pacemaker implantations. Follow-up was completed in 86% of the cases. The median follow-up period was 13 months (range 2 to 129 months). Three patients (43%) died during the follow-up period, at 7 months, 8 months and 13 months, respectively. All deaths were associated with prosthetic valve IE and recurrent intravenous drug use. Conclusions: This study supplements the paucity of data pertaining to tricuspid valve replacement for IE in the local population. Survival outcomes can be improved with prompt surgical intervention, optimal medical optimization, and a holistic, psychosocial approach targeting intravenous drug abuse.

Clinical presentation of cardiac myxoma in a Singapore national cardiac centre.

INTRODUCTION: Cardiac myxoma is the most common cardiac tumour. In this study, we summarise our 17-year experience with the clinical presentation of cardiac myxoma at National Heart Centre Singapore, Singapore. METHODS: Between January 2000 and December 2016, retrospective data was reviewed for all consecutive patients who underwent surgical resection of cardiac myxoma. Patients' clinical characteristics were reviewed and described. RESULTS: A total of 67 (18 male, 49 female; mean age 53.1 ± 13.5 years) patients underwent cardiac myxoma resection. There were 19 (28.4%) patients with asymptomatic cardiac myxoma. There were no significant differences in gender; body habitus and myxoma size; and haemoglobin, white blood cell or platelet counts between patients with symptomatic and asymptomatic myxoma. However, the number of asymptomatic cardiac myxomas seemed to follow an increasing trend from 19.4% (period 2000-2008) to 36.1% (period 2009-2016), suggestive of an 'era effect'. CONCLUSION: In our study, a majority of patients were women, with a wide age range of 18-78 years. The diagnosis of asymptomatic cardiac myxoma was present in 28.4% of patients, with an increasing trend for incidence over the years. This is possibly due to increased opportunistic screening (with electrocardiography and clinical examination) as well as higher usage of medical imaging.

Long-term prognosis in patients with end-stage renal disease after coronary artery bypass grafting.

BACKGROUND: Cardiovascular disease is a major cause of morbidity and mortality in patients with end-stage renal disease (ESRD). Coronary artery bypass grafting (CABG) is beneficial in selected patients with ESRD. This study investigates the survival outcomes and prognostic factors in ESRD patients who underwent CABG. METHODS: A retrospective analysis was performed for 149 patients with ESRD who underwent isolated CABG between 2006 and 2015. RESULTS: Mean age was 59.4±8.7 years and 106 patients (71.1%) were male. Operative mortality occurred in 20 patients (13.4%). Overall survival was 81.1%±3.2% at 1 year, 41.5%±4.3% at 5 years and 19.2%±4.2% at 10 years. Median survival was 4.3 years. Multivariable analysis identified age [P=0.001, odds ratio (OR): 1.15 per 1-year increase, 95% confidence interval (CI): 1.06-1.25], preoperative left ventricular ejection fraction (LVEF) (P=0.020, OR: 0.94, 95% CI: 0.89-0.99) and non-elective status of operation (P=0.049, OR: 3.34, 95% CI: 1.00-11.1) as predictors of operative mortality. Cox regression analysis identified age [P<0.001, hazard ratio (HR): 1.05 per 1-year increase, 95% CI: 1.03-1.08], New York Heart Association (NYHA) class III or IV status (P=0.010, HR: 1.75, 95% CI: 1.15-2.67) and the use of a left internal mammary artery (LIMA) to left anterior descending artery (LIMA-LAD) graft (P=0.029, HR: 0.42, 95% CI: 0.19-0.92) as factors influencing long-term survival. CONCLUSIONS: CABG is associated with high operative mortality and poor long-term survival in ESRD patients. Age and NYHA class influenced late survival. LIMA-LAD grafting conferred a long-term survival advantage.

Restrictive mitral valve annuloplasty for chronic ischaemic mitral regurgitation: outcomes of flexible versus semi-rigid rings.

BACKGROUND: Restrictive mitral annuloplasty is the mainstay of surgical correction of chronic ischaemic mitral regurgitation (CIMR). Long-term data on the various types of annuloplasty rings is limited. The aim of this study was to investigate the clinical and echocardiographic outcomes of restrictive mitral annuloplasty in patients with CIMR, comparing the use of flexible versus semi-rigid annuloplasty rings. METHODS: A retrospective review was conducted for 133 patients with CIMR who underwent restrictive mitral annuloplasty at our institution between 1999 and 2015. Patient demographics and postoperative outcomes were analyzed. RESULTS: Mean age was 61.9±9.2 years and 103 patients (77.4%) were male. All patients underwent coronary artery bypass grafting, with a mean of 3.3±0.8 grafts. Flexible rings was implanted in 39 patients (29.3%, group F) and semi-rigid rings in 94 (70.7%, group R). Preoperative New York Heart Association class was III/IV in 104 patients (78.2%). Mean preoperative left ventricular ejection fraction was 28.8%±10.2%. Preoperative mitral regurgitation was moderate in 51 patients (38.3%) and severe in 82 (61.7%). In-hospital mortality occurred in 11 patients (8.3%). Overall survival at 1, 5 and 10 years were, respectively, 86.4%, 69.7% and 45.9%. At 10 years, overall survival (group F 53.1%, group R 40.0%, P=0.330) and freedom from moderate to severe MR (group F 53.1%, group R 53.8%, P=0.725) did not differ significantly. Freedom from hospitalization for heart failure was 59.3%. Left ventricular reverse remodelling, defined as a reduction of left ventricular end-systolic volume index >15%, occurred more commonly in Group R (51.1%) compared to Group F (23.1%), P=0.003. CONCLUSIONS: Restrictive mitral annuloplasty was associated with an operative mortality of 8.3%. Heart failure symptoms and significant MR recur in approximately 40% of patients after 10 years. Survival remained suboptimal and was not influenced by the type of annuloplasty ring.

Impact of Intubation Time on Survival following Coronary Artery Bypass Grafting: Insights from the Surgical Treatment for Ischemic Heart Failure (STICH) Trial.

OBJECTIVE: The authors aimed to assess determinants of intubation time and evaluate its impact on 30-day and 1-year postoperative survival in Surgical Treatment for Ischemic Heart Failure (STICH) trial patients. DESIGN, SETTING, PARTICIPANTS, AND INTERVENTIONS: A multivariable Cox proportional hazards model was used among the 1,446 surgical patients from the STICH trial who survived 36 hours after operation, in order to identify perioperative factors associated with 30-day and 1-year postoperative mortality. A multivariable logistic regression model was used to determine risk factors associated with intubation time. MEASUREMENTS AND MAIN RESULTS: At 36 hours post-operation, 1,298 (out of 1,446) were extubated and 148 (10.2%) still intubated. Median postoperative intubation time was 11.4 hours. Among patients surviving 36 hours, a multivariable model was developed to predict 30-day (c-index = 0.88) and 1-year (c-index = 0.78) mortality. Intubation time was the strongest independent predictor of 30-day (hazard ratio [HR] 5.50) and 1-year mortality (HR 3.69). Predictors of intubation time >36 hours included mitral valve procedure, New York Heart Association class, left ventricular systolic volume index, creatinine, previous coronary artery bypass grafting (CABG), and age. Results were similar in patients surviving 24 hours post-operation, where intubation time was also the strongest predictor of 30-day (HR 4.18, c-index 0.87) and 1-year (HR 2.81, c-index 0.78) mortality. CONCLUSIONS: Intubation time is the strongest predictor of 30-day and 1-year mortality among patients with ischemic heart failure undergoing CABG. Combining intubation time with other mortality risk factors may allow the identification of patients at the highest risk for whom the development of specific strategies may improve outcomes.

Quadriplegia post-coronary artery bypass graft surgery: an unusual case.

A 74-year-old Chinese man with triple-vessel coronary artery disease, developed quadriplegia following coronary artery bypass graft surgery, secondary to cervical disc anterior herniation and a C5-6 to T1 acute spinal hematoma. Preoperatively, no neurological signs or symptoms had been reported.

Successful anticoagulation therapy for a giant left atrial thrombus following mitral valve repair.

A 72-year-old male with atrial fibrillation (AF) underwent mitral valve (MV) repair and concomitant procedures. He was discharged with therapeutic Warfarin dosing but was readmitted 3 weeks later with a right caudate nucleus infarct and subtherapeutic anticoagulation. Echocardiography showed a giant left atrial (LA) thrombus. Low-molecular-weight heparin was promptly initiated. Unfortunately, the patient suffered an intracranial hemorrhage (ICH) 2 days later. He declined surgical thrombectomy and was managed conservatively, remaining stable without neurological deficits. Serial brain imaging showed interval stability, allowing Warfarin to be resumed. Follow-up echocardiography demonstrated partial and complete resolution of the thrombus at 1 and 3 months, respectively.

Surgical management of very late paravalvular leaks after mitral valve replacement: a single institutional experience.

Most mitral paravalvular leaks (PVLs) occur during the first year after mitral valve replacement (MVR). This report describes the surgical management of 6 patients who developed very late mitral PVLs. The median interval between MVR and initial diagnosis of PVL was 16.5 years. All patients presented with congestive cardiac failure and haemolytic anaemia. The median EuroSCORE II was 9.5%. Two patients (33%) had failed attempts at transcatheter closure. Five patients underwent suture repair of the PVL. One patient underwent MVR after removal of the previous prosthesis. No in-hospital mortalities occurred. At latest follow-up (median 3.3 years), 5 patients (83%) were asymptomatic with no residual PVL. Haemolytic anaemia persisted in 1 patient with a mild residual PVL. PVL occurring decades after MVR is a rare but serious complication. Reoperative surgery can be performed in these high-risk patients with satisfactory early and midterm outcomes.

Percutaneous transcatheter aortic valve implantation for degenerated surgical bioprostheses: the first case series in Asia with one-year follow-up.

INTRODUCTION: Percutaneous transcatheter aortic valve implantation (TAVI) has become an established therapy for inoperable and high-surgical-risk patients with severe aortic stenosis. Although TAVI in patients with degenerated surgical aortic bioprostheses (i.e. valve-in-valve TAVI) is increasingly reported in Western studies, such data is lacking in Asian patients. We describe the initial experience of valve-in-valve TAVI in Asia. METHODS: Eight patients who underwent valve-in-valve TAVI due to degenerated aortic bioprostheses were enrolled. The mechanism of bioprosthetic valve failure was stenotic, regurgitation or mixed. All procedures were performed via transfemoral arterial access, using the self-expanding CoreValve prosthesis or balloon-expandable SAPIEN XT prosthesis. RESULTS: The mean age of the patients was 71.6 ± 13.2 years and five were male. Mean duration to surgical bioprosthesis degeneration was 10.2 ± 4.1 years. Valve-in-valve TAVI was successfully performed in all patients. CoreValve and SAPIEN XT prostheses were used in six and two patients, respectively. There were no deaths, strokes or permanent pacemaker requirement at 30 days, with one noncardiac mortality at one year. All patients experienced New York Heart Association functional class improvement. Post-procedure mean pressure gradients were 20 ± 11 mmHg and 22 ± 8 mmHg at 30 days and one year, respectively. Residual aortic regurgitation (AR) of more than mild severity occurred in one patient at 30 days. At one year, only one patient had mild residual AR. CONCLUSION: In our experience of valve-in-valve TAVI, procedural success was achieved in all patients without adverse events at 30 days. Good clinical and haemodynamic outcomes were sustained at one year.

2015 Young Surgeon's Award Winner: Long-term Prognosis in Patients with Diabetes Mellitus after Coronary Artery Bypass Grafting: A Propensity-Matched Study.

INTRODUCTION: We aimed to determine the impact of diabetes mellitus (DM) on long-term survival after coronary artery bypass grafting (CABG) in patients with multivessel coronary artery disease. MATERIALS AND METHODS: A retrospective review was conducted for 5720 consecutive patients who underwent isolated first CABG between 1982 and 1999. Outcomes were reviewed to include in-hospital mortality and long-term survival. Mean follow-up was 13.0 ± 5.8 years. To obtain comparable subgroups, 561 diabetic patients were matched with 561 non-diabetic controls based on estimated propensity scores. RESULTS: Mean age was 59.3 ± 9.1 years with 4373 (76.5%) males. Amongst 5720 patients, 1977 (34.6%) had DM. Hypertension and dyslipidaemia were the most common cardiovascular comorbidities, present in 2920 (51.0%) and 2664 patients (46.6%) respectively. Emergency surgery was performed in 563 patients (9.8%). In-patient mortality occurred in 115 patients (2.0%), 48 (2.4%) in the DM group and 67 (1.8%) in the non-DM group, (P = 0.102). In the unmatched cohort, overall 20-year survival rates were 30.9 ± 1.6% in diabetics and 49.2 ± 1.0% in non-diabetics (P <0.001). Freedom from cardiac mortality at 20 years was 56.0 ± 2.0% in diabetics and 68.4 ± 1.0% in non-diabetics (P <0.001). In the propensity-matched group, overall 20-year survival rates were 35.4 ± 2.5% in diabetics and 48.9 ± 2.9% in non-diabetics (P <0.001). Freedom from cardiac mortality at 20 years was 57.8 ± 3.0% in diabetics and 70.2 ± 2.9% in non-diabetics (P = 0.001). Multivariable Cox regression analysis identified age (hazard ratio (HR): 1.03/year), female gender (HR: 1.43), DM (HR: 1.51), previous myocardial infarction (HR: 1.54) and left ventricular ejection fraction (LVEF) <35% (HR: 2.60) as independent factors influencing long-term cardiac mortality. CONCLUSION: Despite low operative mortality, long-term survival and freedom from cardiac death are significantly lower in patients with DM compared to non-diabetics. Aggressive treatment of DM, cardiovascular comorbidities and smoking cessation are essential to improve long-term survival in diabetic patients.

Chordal Reconstruction versus Leaflet Resection for Repair of Degenerative Posterior Mitral Leaflet Prolapse.

OBJECTIVE: To review our experience of mitral valve repair for degenerative posterior mitral leaflet prolapse, comparing the outcomes of chordal reconstruction and leaflet resection. METHODS: From 2000 to 2014, 205 patients underwent successful repair for degenerative posterior mitral leaflet prolapse. One hundred and four (51.5%) underwent leaflet resection (group R) and 98 (48.5%) underwent chordal reconstruction (group C). Follow-up was 96.5% complete with a mean follow-up of 6.1 ± 4.0 years. RESULTS: Mean age was 57.0 ± 11.0 years. Males accounted for 73.8%. Ring annuloplasty was performed in 195 (96.5%). There were no operative mortalities within 30 days. Overall survival was 97.8% ± 1.3% at 7 years. Outcomes at 6 years: freedom from severe mitral regurgitation (group R 97.1% ± 2.0%, group C 100%, P = 0.288), freedom from moderate or severe mitral regurgitation (group R 97.1% ± 2.0%, group C 94.4% ± 5.4%, P = 0.541). Group C patients received larger annuloplasty rings and had significantly lower postoperative transmitral gradients. CONCLUSIONS: Leaflet resection and chordal reconstruction are effective techniques for repair of degenerative posterior mitral leaflet prolapse. Both techniques result in a low incidence of recurrent mitral regurgitation. Chordal reconstruction accommodates larger annuloplasty rings and is associated with lower transmitral gradients.

Late Presentation of an Inferior Myocardial Infarction Complicated by Ventricular Septal Rupture: A Case Report.

Ventricular septal rupture (VSR) is a well-described and potentially fatal complication of acute myocardial infarctions. In the era of early reperfusion therapy, the incidence has been on the decline. We describe a case of delayed presentation inferior myocardial infarction complicated by VSR requiring early surgery and review our center's experience.

Alternative splicing generates a novel truncated Cav1.2 channel in neonatal rat heart.

L-type Cav1.2 Ca(2+) channel undergoes extensive alternative splicing, generating functionally different channels. Alternatively spliced Cav1.2 Ca(2+) channels have been found to be expressed in a tissue-specific manner or under pathological conditions. To provide a more comprehensive understanding of alternative splicing in Cav1.2 channel, we systematically investigated the splicing patterns in the neonatal and adult rat hearts. The neonatal heart expresses a novel 104-bp exon 33L at the IVS3-4 linker that is generated by the use of an alternative acceptor site. Inclusion of exon 33L causes frameshift and C-terminal truncation. Whole-cell electrophysiological recordings of Cav1.233L channels expressed in HEK 293 cells did not detect any current. However, when co-expressed with wild type Cav1.2 channels, Cav1.233L channels reduced the current density and altered the electrophysiological properties of the wild type Cav1.2 channels. Interestingly, the truncated 3.5-domain Cav1.233L channels also yielded a dominant negative effect on Cav1.3 channels, but not on Cav3.2 channels, suggesting that Cavß subunits is required for Cav1.233L regulation. A biochemical study provided evidence that Cav1.233L channels enhanced protein degradation of wild type channels via the ubiquitin-proteasome system. Although the physiological significance of the Cav1.233L channels in neonatal heart is still unknown, our report demonstrates the ability of this novel truncated channel to modulate the activity of the functional Cav1.2 channels. Moreover, the human Cav1.2 channel also contains exon 33L that is developmentally regulated in heart. Unexpectedly, human exon 33L has a one-nucleotide insertion that allowed in-frame translation of a full Cav1.2 channel. An electrophysiological study showed that human Cav1.233L channel is a functional channel but conducts Ca(2+) ions at a much lower level.

Surgical management of infective endocarditis: an analysis of early and late outcomes.

OBJECTIVES: To review our experience of surgical management of infective endocarditis (IE) over a 13-year period and analyse the outcomes and associated prognostic factors. METHODS: A retrospective review was conducted for 191 consecutive patients who underwent surgery for native and prosthetic valve endocarditis (PVE) between January 2000 and December 2012. Surgical outcomes were reviewed to include survival and postoperative complications. Follow-up was complete for 172 of 179 patients (96.1%) surviving to hospital discharge, with a mean follow-up of 6.6 ± 3.7 years. RESULTS: Mean age was 47.4 ± 14.9 years with 113 (63.9%) males. Native valve endocarditis was present in 177 patients (92.7%). Sixty-three patients (33.0%) presented with embolic complications. The brain was the most common site of embolism, involving 25 patients (13.1%). Streptococcus viridans was the most common infective organism, isolated in 68 patients (35.7%), followed by Staphylococcus aureus in 30 patients (15.7%). Eighty-seven patients (45.5%) had active endocarditis at the time of surgery. The mitral valve was infected in 136 patients (71.2%), the aortic valve in 66 (34.6%), the tricuspid valve in 29 (15.2%) and multiple valves in 38 (19.9%). Nineteen patients (9.9%) were intravenous drug users (IVDU). Twelve IVDUs (63.2%) suffered from tricuspid valve IE, compared with 7 of 162 patients (4.3%) in the non-IVDU population (P < 0.001). The most common indication for early surgery was intractable cardiac failure. Twelve patients (6.3%) died during the hospital stay for surgical treatment of IE. Logistic multivariate analysis identified preoperative creatinine clearance and stroke as independent predictors of in-hospital mortality. Overall 10-year survival and freedom from valve-related reoperation were 74.8 and 90.3%, respectively. Age, PVE, S. aureus endocarditis and postoperative left ventricular ejection fraction (LVEF) ≤45% were factors influencing long-term survival. CONCLUSIONS: Surgical management of endocarditis continues to be challenging and is associated with significant morbidity and mortality. This report of 191 patients who underwent valve surgery for IE shows that in-hospital mortality is influenced by preoperative renal function and stroke at the time of presentation. The optimal timing for surgery in patients with stroke remains controversial. Long-term survival was negatively influenced by increasing age, moderate to severely impaired LVEF, prosthetic valve IE and S. aureus infection.

First transcatheter aortic valve implantation for severe pure aortic regurgitation in Asia.

Transcatheter aortic valve implantation (TAVI) has become the standard of care for inoperable patients with symptomatic severe aortic stenosis (AS), and an alternative to open aortic valve replacement for patients at high surgical risk. TAVI has also been performed in several groups of patients with off-label indications such as severe bicuspid AS, and as a valve-in-valve therapy for a degenerated surgical bioprosthesis. Although TAVI with CoreValve® prosthesis is technically challenging, and global experience in the procedure is limited, the procedure could be a treatment option for well-selected patients with severe pure aortic regurgitation (AR). Herein, we report Asia's first case of TAVI for severe pure AR in a patient who was at extreme surgical risk, with good clinical outcome at six months.

Electrophysiology of human cardiac atrial and ventricular telocytes.

Telocytes (TCs) with exceptionally long cellular processes of telopodes have been described in human epicardium to act as structural supporting cells in the heart. We examined myocardial chamber-specific TCs identified in atrial and ventricular fibroblast culture using immunocytochemistry and studied their electrophysiological property by whole-cell patch clamp. Atrial and ventricular TCs with extended telopodes and alternating podoms and podomers that expressed CD34, c-Kit and PDGFR-ß were identified. These cells expressed large conductance Ca²âº-activated K⁺ current (BK(Ca)) and inwardly rectifying K⁺ current (IK(ir)), but not transient outward K⁺ current (I(to)) and ATP-sensitive potassium current (K(ATP)). The active channels were functionally competent with demonstrated modulatory response to H2 S and transforming growth factor (TGF)-ß1 whereby H2S significantly inhibited the stimulatory effect of TGF-ß1 on current density of both BKCa and IK(ir). Furthermore, H2S attenuated TGF-ß1-stimulated KCa1.1/Kv1.1 (encode BK(Ca)) and Kir2.1 (encode IK(ir)) expression in TCs. Our results show that functionally competent K⁺ channels are present in human atrial and ventricular TCs and their modulation may have significant implications in myocardial physiopathology.