In-Person Clinic Visits After Laparoscopic Cholecystectomy: Lessons Learned From COVID-19 Pandemic

INTRODUCTION

The utility of routine in-person clinic appointments after laparoscopic cholecystectomy (LC) is uncertain, especially after the increase of telehealth visits during the COVID-19 pandemic. The purpose of this study was to evaluate the utility of routine in-person follow-up for patients undergoing LC prior to changes implemented during the pandemic and to determine whether a return to routine in-person follow-up is warranted.

METHODS

We retrospectively reviewed follow-up encounters for all patients undergoing LC from April 2018 to February 2020. All patients were routinely scheduled for in-person postoperative clinic follow-up 2-4 wk after discharge. Follow-up was considered nonroutine if new studies or medications were ordered, the patient was referred to the emergency department or readmitted, or malignancy was identified on pathology review.

RESULTS

Of 661 patients undergoing LC, 449 (68%) attended their scheduled in-person postoperative appointment and 212 (32%) did not. The postoperative appointment was nonroutine for 39 patients (9% of clinic attenders). Readmission occurred in 42 patients, with no differences between clinic attenders and nonattenders (P = 0.12). Furthermore, attending a postoperative clinic visit did not affect odds of readmission (odds ratio: 0.705, 95% confidence interval: 0.368, 1.351; P = 0.29). Readmission occurred on median day 9 after discharge in both groups.

CONCLUSIONS

The incidence of nonroutine follow-up after LC is low, and attendance at follow-up clinic was not associated with reduced readmissions. A return to routinely scheduling in-person follow-up 2-4 wk after discharge may not be warranted. Telehealth visits within 1 wk of discharge after LC should be considered.

Outcomes of the Ross procedure in patients older versus younger than 50 years old

OBJECTIVES

The Ross procedure is traditionally considered for young adult patients with aortic valve disease. This study compares long-term outcomes of patients undergoing the Ross procedure who are ≥50 and <50-years old.

METHODS

Data were collected from 225 patients undergoing Ross procedure at a single centre from 1994 to 2019. Patients were categorized into younger (<50-years old; n = 156) and older (≥50-years old; n = 69) cohorts. Baseline demographics clinical outcomes were compared.

RESULTS

The mean age was 36 ± 8.1 and 55 ± 4.2 years in the younger and older cohort, respectively. Both groups were predominantly male (58.5% vs 69.6%; P = 0.59). The younger group had a higher rate of aortic insufficiency (51% vs 26.1%; P < 0.01), and bicuspid aortic valve (81.4% vs 58.0%; P < 0.01). Aortic stenosis was more prevalent in the older cohort (25.6% vs 58.0%; P < 0.01). Operative mortality was acceptable in both groups (1.3% vs 4.3%; P = 0.15). Survival up to 10 years was not statistically different between 2 groups (96.2% vs 91.3% P = 0.16), whereas survival up to 15 years for younger patients was significantly higher (94.9% vs 85.5%; P = 0.03). After non-cardiac related deaths were excluded, survival up to 15 years (98.7% vs 91.3%; P = 0.02) was significantly lower than younger patients. In both groups, survival after the Ross procedure was similar to the age- and sex-matched US population.

CONCLUSIONS

Survival up to 10 years after Ross procedure were similar, but up to 15 years was significantly higher in younger patients. The Ross procedure restored patients from both groups to expected survival. Our results suggest that at experienced centres, the Ross procedure is a safe and reasonable option for patients who are 50 years and older.

Impact of Mitral Regurgitation Etiology on Mitral Surgery After Transcatheter Edge-to-Edge Repair: From the CUTTING-EDGE Registry

BACKGROUND

Although >150,000 mitral TEER procedures have been performed worldwide, the impact of MR etiology on MV surgery after TEER remains unknown.

OBJECTIVES

The authors sought to compare outcomes of mitral valve (MV) surgery after failed transcatheter edge-to-edge repair (TEER) stratified by mitral regurgitation (MR) etiology.

METHODS

Data from the CUTTING-EDGE registry were retrospectively analyzed. Surgeries were stratified by MR etiology: primary (PMR) and secondary (SMR). MVARC (Mitral Valve Academic Research Consortium) outcomes at 30 days and 1 year were evaluated. Median follow-up was 9.1 months (IQR: 1.1-25.8 months) after surgery.

RESULTS

From July 2009 to July 2020, 330 patients underwent MV surgery after TEER, of which 47% had PMR and 53.0% had SMR. Mean age was 73.8 ± 10.1 years, median STS risk at initial TEER was 4.0% (IQR: 2.2%-7.3%). Compared with PMR, SMR had a higher EuroSCORE, more comorbidities, lower LVEF pre-TEER and presurgery (all P < 0.05). SMR patients had more aborted TEER (25.7% vs 16.3%; P = 0.043), more surgery for mitral stenosis after TEER (19.4% vs 9.0%; P = 0.008), and fewer MV repairs (4.0% vs 11.0%; P = 0.019). Thirty-day mortality was numerically higher in SMR (20.4% vs 12.7%; P = 0.072), with an observed-to-expected ratio of 3.6 (95% CI: 1.9-5.3) overall, 2.6 (95% CI: 1.2-4.0) in PMR, and 4.6 (95% CI: 2.6-6.6) in SMR. SMR had significantly higher 1-year mortality (38.3% vs 23.2%; P = 0.019). On Kaplan-Meier analysis, the actuarial estimates of cumulative survival were significantly lower in SMR at 1 and 3 years.

CONCLUSIONS

The risk of MV surgery after TEER is nontrivial, with higher mortality after surgery, especially in SMR patients. These findings provide valuable data for further research to improve these outcomes.

Vein Graft Use and Long-Term Survival Following Coronary Bypass Grafting

BACKGROUND

Although placement of at least 1 arterial graft during coronary artery bypass grafting (CABG) has a proven survival benefit, it is unknown what degree of revascularization with saphenous vein grafting (SVG) is associated with improved survival.

OBJECTIVES

The authors sought to determine whether undergoing surgery performed by a surgeon who is liberal with vein graft utilization is associated with improved survival in patients undergoing single arterial graft CABG (SAG-CABG).

METHODS

This was a retrospective, observational study of SAG-CABG performed in Medicare beneficiaries from 2001 to 2015. Surgeons were stratified by number of SVG utilized per SAG-CABG into conservative (≥1 SD below mean), average (within 1 SD of mean), and liberal (≥1 SD above mean). Long-term survival was estimated using Kaplan-Meier analysis and compared among surgeon groups before and after augmented inverse-probability weighting.

RESULTS

There were 1,028,264 Medicare beneficiaries undergoing SAG-CABG from 2001 to 2015 (mean age 72.0 ± 7.9 years, 68.3% male). Over time, 1-vein and 2-vein SAG-CABG utilization increased, whereas 3-vein and ≥4-vein SAG-CABG utilization decreased (P < 0.001). Surgeons who were conservative vein graft users performed a mean 1.7 ± 0.2 vein grafts per SAG-CABG, whereas those who were liberal vein graft users performed a mean 2.9 ± 0.2 vein grafts per SAG-CABG. Weighted analysis demonstrated no difference in median survival among patients undergoing SAG-CABG by liberal vs conservative vein graft users (adjusted median survival difference 27 days).

CONCLUSIONS

Among Medicare beneficiaries undergoing SAG-CABG, there is no association between surgeon proclivity for vein graft utilization and long-term survival, suggesting that a conservative approach to vein graft utilization is reasonable.

Race, neighborhood disadvantage, and survival of Medicare beneficiaries after aortic valve replacement and concomitant coronary artery bypass grafting

BACKGROUND

Race, neighborhood disadvantage, and the interaction between these 2 social determinants of health remain poorly understood with regards to survival after aortic valve replacement with concomitant coronary artery bypass grafting (AVR+CABG).

METHODS

Weighted Kaplan-Meier survival analyses and Cox proportional hazards modeling were used to evaluate the association between race, neighborhood disadvantage, and long-term survival in 205,408 Medicare beneficiaries undergoing AVR+CABG from 1999 to 2015. Neighborhood disadvantage was measured using the Area Deprivation Index, a broadly validated ranking of socioeconomic contextual disadvantage.

RESULTS

Self-identified race was 93.9% White and 3.2% Black. Residents of the most disadvantaged quintile of neighborhoods included 12.6% of all White beneficiaries and 40.0% of all Black beneficiaries. Black beneficiaries and residents of the most disadvantaged quintile of neighborhoods had more comorbidities compared with White beneficiaries and residents of the least disadvantaged quintile of neighborhoods, respectively. Increasing neighborhood disadvantage linearly increased the hazard for mortality for Medicare beneficiaries of White but not Black race. Residents of the most and least disadvantaged neighborhood quintiles had weighted median overall survival of 93.0 and 82.1 months, respectively, a significant difference (P < .001 by Cox test for equality of survival curves). Black and White beneficiaries had weighted median overall survival of 93.4 and 90.6 months, respectively, a nonsignificant difference (P = .29 by Cox test for equality of survival curves). A statistically significant interaction between race and neighborhood disadvantage was noted (likelihood ratio test P = .0215) and had implications on whether Black race was associated with survival.

CONCLUSIONS

Increasing neighborhood disadvantage was linearly associated with worse survival after combined AVR+CABG in White but not Black Medicare beneficiaries; race, however, was not independently associated with postoperative survival.

Fast-Track Nonelective Laparoscopic Cholecystectomy is Safe and Feasible

INTRODUCTION

Ample evidence exists to support the safety of fast-track discharge after elective laparoscopic cholecystectomy (LC), but there is currently no data available to support the safety of fast-tracking patients undergoing nonelective LC. We sought to determine whether fast-tracking patients undergoing nonelective LC is safe and feasible.

METHODS

We performed a retrospective cohort review of 661 consecutive patients undergoing LC at a single teaching institution from April 2018 to January 2020. Subjects were divided into two groups: elective LC (ELC) and fast-track nonelective LC (FTLC). FTLC was defined as nonelective LC with total length of stay <36 h. Patients undergoing nonelective LC with length of stay exceeding 36 h were excluded. The primary outcome of interest was readmission within 30 d. The secondary outcomes included incidences of return to emergency department within 30 d, retained stone, bile leak, and wound infection.

RESULTS

Of 661 LC, 185 (27%) were ELC and 476 (72%) were nonelective. FTLC included 121 (25%) of the nonelective LC. Preoperative characteristics were similar among the groups. On final pathology, chronic cholecystitis was predominant in both groups, but FTLC exhibited higher rates of acute cholecystitis (P < 0.0001). There was no significant difference in the primary outcome among groups: readmission within 30 d occurred in 6 (3%) ELC patients and 4 (3%) FTLC patients (P = 1.0). There were no significant differences in rates of return to emergency department within 30 d, retained stone, bile leak, or wound infection.

CONCLUSIONS

With comparable postoperative complication rates to ELC, FTLC can be safely used in select patients. Additional studies are needed to determine preoperative predictors of FTLC suitability to prospectively identify appropriate patients.

Bloodstream and respiratory coinfections in patients with COVID-19 on ECMO

BACKGROUND

Although several studies have characterized the risk of coinfection in COVID pneumonia, the risk of the bloodstream and respiratory coinfection in patients with COVID-19 pneumonia on extracorporeal membrane oxygenation (ECMO) supports severe acute respiratory distress syndrome (ARDS) is poorly understood.

METHODS

This is a retrospective analysis of patients with COVID-19 ARDS on ECMO at a single center between January 2020 and December 2021. Patient characteristics and clinical outcomes were compared.

RESULTS

Of 44 patients placed on ECMO support for COVID-19 ARDS, 30 (68.2%) patients developed a coinfection, and 14 (31.8%) patients did not. Most patients underwent venovenous ECMO (98%; 43/44) cannulation in the right internal jugular vein (98%; 43/44). Patients with coinfection had a longer duration of ECMO (34 [interquartile range, IQR: 19.5, 65] vs. 15.5 [IQR 11, 27.3] days; p = .02), intensive care unit (ICU; 44 [IQR: 27,75.5] vs 31 [IQR 20-39.5] days; p = .03), and hospital (56.5 [IQR 27,75.5] vs 37.5 [IQR: 20.5-43.3]; p = .02) length of stay. When stratified by the presence of a coinfection, there was no difference in hospital mortality (37% vs. 29%; p = .46) or Kaplan-Meier survival (logrank p = .82). Time from ECMO to first positive blood and respiratory culture were 12 [IQR: 3, 28] and 10 [IQR: 1, 15] days, respectively. Freedom from any coinfection was 50 (95% confidence interval: 37.2-67.2)% at 15 days from ECMO initiation.

CONCLUSIONS

There is a high rate of co-infections in patients placed on ECMO for COVID-19 ARDS. Although patients with coinfections had a longer duration of extracorporeal life support, and longer length of stays in the ICU and hospital, survival was not inferior.

Real-world validation of fractional flow reserve computed tomography in patients with stable angina: Results from the prospective AFFECTS trial

BACKGROUND

Fractional flow reserve computed tomography (FFRct) allows for non-invasive assessment of hemodynamically significant coronary artery disease (CAD). Real-world data regarding the diagnostic performance of FFRct is scarce. We aim to validate the diagnostic performance of FFRct against invasive coronary angiography (ICA) in patients with stable angina and an abnormal single photon emission computed tomography (SPECT) study.

METHODS

This prospective, single-cohort, real-world study enrolled consecutive adult patients with stable angina and an abnormal SPECT study who were referred for ICA. Prior to ICA, FFRct analysis was performed. Sensitivity and specificity of FFRct were evaluated at the patient and vessel level against ICA. Physician intuition-based diagnosis of hemodynamically significant CAD was also documented prior to ICA.

RESULTS

A total of 66 patients were enrolled; 10 were excluded due to protocol deviation or missing studies. FFRct achieved 95% sensitivity and 83% specificity at the patient level, and 78% sensitivity and 88% specificity at the vessel level. FFRct was most accurate in the left circumflex artery (sensitivity 83%, specificity 92%) and the least in the left anterior descending artery (80% sensitivity, 78% specificity). FFRct identified hemodynamically significant CAD more accurately than physician intuition (sensitivity 95% vs 84%; specificity 83% vs 46%). If physicians had been unblinded to FFRct, ICA may have been avoided in up to 53% of patients.

CONCLUSION

We performed a real-world study to validate the diagnostic performance of FFRct against gold-standard invasive imaging. FFRct has high sensitivity and specificity for the diagnosis of hemodynamically significant CAD in intermediate-to-high risk patients.

Outcomes of Redo Operations after Ross procedure

BACKGROUND

The Ross procedure is not commonly performed, owing to the procedural complexity and the risk of autograft and/or homograft reoperation. This study examined outcomes of patients undergoing Ross reinterventions at a dedicated Ross center.

METHODS

We retrospectively reviewed 225 consecutive patients who underwent a Ross procedure between 1994 and 2019. Index and redo operation characteristics and outcomes were compared between patients with and those without redo operations. Multivariate analysis was used to identify independent predictors of Ross-related reinterventions. Survival was estimated with Kaplan-Meier analysis.

RESULTS

Sixty-six patients (29.3%) required redo Ross surgery, 41 patients (18.2%) underwent autograft reoperation only, 8 patients (3.6%) had a homograft reintervention, and 17 patients (7.6%) had both autograft and homograft reoperations (12 as a combined procedure and 5 as sequential procedures). The mean time to reintervention was 11 ± 6 years for autograft reoperations and 12 ± 7 years for homograft reoperations. Patients who underwent Ross-related reinterventions were younger (mean, 38 ± 11 years vs 43 ± 11 years; P < .01) and had a higher rate of New York Heart Association class III/IV (56% vs 38%; P = .02) at the index Ross procedure. Most patients undergoing autograft reintervention had aortic insufficiency and/or aneurysm (98.2%; 57 of 58). The primary reason for homograft reintervention was pulmonary stenosis (92%; 23 of 25). The operative mortality of Ross reintervention was 1.5% (1 of 66). Survival at 15 years was similar in patients who required a redo operation and those who did not (91.2% vs 93.9%; P = .23).

CONCLUSIONS

Ross reinterventions can be performed safely and maintain patients at the normal life expectancy restored by the index Ross procedure up to 15 years at experienced centers.

Extracorporeal membrane oxygenation for respiratory failure in phases of COVID-19 variants

Background

Adaptive mutations of the severe acute respiratory syndrome‐related coronavirus (SARS‐CoV‐2) virus have emerged throughout the coronavirus disease 2019 (COVID‐19) pandemic. The characterization of outcomes in patients requiring extracorporeal membrane oxygenation (ECMO) for severe respiratory distress from COVID‐19 during the peak prevalence of different variants is not well known.

Methods

There were 131 patients with laboratory‐confirmed SARS‐CoV‐2 infection supported by ECMO at two referral centers within a large healthcare system. Three predominant variant phase time windows (Pre‐Alpha, Alpha, and Delta) were determined by a change‐point analyzer based on random population sampling and viral genome sequencing. Patient demographics and outcomes were compared.

Results

The average age of patients was 46.9 ± 10.5 years and 70.2% (92/131) were male. Patients cannulated for ECMO during the Delta variant wave were younger compared to earlier Pre‐Alpha (39.3 ± 7.8 vs. 48.0 ± 11.1 years) and Alpha phases (39.3 ± 7.8 vs. 47.2 ± 7.7 years) (p < .01). The predominantly affected race in the Pre‐Alpha phase was Hispanic (52.2%; 47/90), while in Alpha (61.5%; 16/26) and Delta (40%; 6/15) variant waves, most patients were White (p < .01). Most patients received a tracheostomy (82.4%; 108/131) with a trend toward early intervention in later phases compared to Pre‐Alpha (p < .01). There was no significant difference between the duration of ECMO, mechanical support, intensive care unit (ICU) length of stay (LOS), or hospital LOS over the three variant phases. The in‐hospital mortality was overall 41.5% (54/131) and was also similar. Six‐month survival of patients who survived to discharge was 92.2% (71/77).

Conclusions

There was no significant difference in survival or time on ECMO support in patients during the peak prevalence of the three variants.

Robotic Mitral Valve Surgery After Prior Sternotomy

Objective

Despite the recent increase in the use of minimally invasive approaches to mitral valve surgery in patients with a prior sternotomy, the outcomes of the robotic approach to mitral valve surgery in this patient population have not been examined.

Methods

We retrospectively reviewed 342 consecutive patients who underwent mitral valve surgery after a prior sternotomy between 2013 and 2020, in which the robotic approach was used in 21 patients (6.1%). We reviewed the clinical details of these 21 patients.

Results

The median age was 71 years [interquartile range 64.00, 74.00 years], and mean Society of Thoracic Surgeons Predicted Risk of Mortality was 4.2% ± 3.8%. The indication for mitral valve surgery was degenerative mitral valve disease in 33.3% (7/21), functional disease in 28.6% (6/21), mixed disease in 4.8% (1/21), rheumatic disease in 9.5% (2/21), and failed repair for degenerative disease in 23.8% (5/21). No cases required conversion from robotic assistance to alternative approaches, there were no intraoperative deaths, and intraoperative transesophageal echocardiogram confirmed complete elimination of mitral regurgitation in 90.5% (19/21) of cases. Thirty-day mortality was 0.0% (0/21), and 1-year mortality was 4.8% (1/21). There were no strokes or wound infections at 30 days, and 14.3% (3/21) of patients received intraoperative blood product transfusions.

Conclusions

The results of this retrospective review suggest that the robotic approach to mitral valve surgery in patients with a prior sternotomy is safe in experienced hands. Although some centers have considered prior sternotomy a relative contraindication to robotic mitral valve surgery, this approach is feasible and can be considered an option for experienced surgeons.

Surgical Debranching versus Branched Endografting in Zone 2 Thoracic Endovascular Aortic Repair

INTRODUCTION

Left subclavian artery (LSA) revascularization is recommended in patients undergoing elective thoracic endovascular aortic repair (TEVAR) with proximal zone 2 landing requiring coverage of the LSA. The gold-standard remains surgical LSA revascularization, but recently the feasibility of branched endografts has been demonstrated. We compared the perioperative and mid-term outcomes of these approaches.

METHODS

A retrospective review of consecutive patients undergoing TEVAR with proximal zone 2 landing at a single center from 2014-2020 was performed. Patients were divided into cohorts for comparison: those undergoing surgical revascularization (SR-TEVAR group) and those undergoing thoracic branched endografting with an investigational device (TBE group). Patients who did not receive LSA revascularization were excluded. Perioperative outcomes including procedural success, death, stroke, limb ischemia, and length of stay were compared. Kaplan-Meier survival curves were compared with the log-rank test. The cumulative incidences of device-related endoleak (type I and III) and device-related reintervention, accounting for death as a competing hazard, were compared with the Fine-Gray test.

RESULTS

A total of 55 patients were included: 31 (56%) SR-TEVAR and 24 (44%) TBE. Preoperative demographics and comorbidities were similar between the groups. Procedural success was 100% in both cohorts, and there were no periprocedural strokes or left upper extremity ischemic events. One operative/30-day mortality (TBE 4.2% vs SR-TEVAR 3.2%, p=0.99) occurred in each cohort. Total operative time (minutes, TBE 203 ± 79 vs SR-TEVAR 250 ± 79 p=0.03) and total length of stay (days, TBE 5.2 ± 3.6 vs SR-TEVAR 9.9 ± 7.2, p=0.004) were both significantly shorter in the TBE group. There was no difference in mid-term survival (log-rank p=0.50), nor the cumulative incidence of device-related endoleak (Fine-Gray p=0.51) or reintervention (Fine-Gray p=0.72). There have been no occlusions of the TBE graft nor surgical bypass/transpositions after a mean follow-up for 28 ± 16 and 34 ± 24 months, respectively.

CONCLUSIONS

Thoracic branched endografting can be performed with similar procedural success and comparable safety profile to TEVAR with surgical revascularization, while reducing total length of stay, in patients requiring proximal zone 2 coverage. Mid-term outcomes of each approach are also similar. Prospective, randomized comparisons of these techniques are warranted.

Machine learning analysis of multispectral imaging and clinical risk factors to predict amputation wound healing

OBJECTIVE

Prediction of amputation wound healing is challenging due to the multifactorial nature of critical limb ischemia and lack of objective assessment tools. Up to one-third of amputations require revision to a more proximal level within 1 year. We tested a novel wound imaging system to predict amputation wound healing at initial evaluation.

METHODS

Patients planned to undergo amputation due to critical limb ischemia were prospectively enrolled. Clinicians evaluated the patients in traditional fashion, and all clinical decisions for amputation level were determined by the clinician's judgement. Multispectral images of the lower extremity were obtained preoperatively using a novel wound imaging system. Clinicians were blinded to the machine analysis. A standardized wound healing assessment was performed on postoperative day 30 by physical exam to determine whether the amputation site achieved complete healing. If operative revision or higher level of amputation was required, this was undertaken based solely upon the provider's clinical judgement. A machine learning algorithm combining the multispectral imaging data with patient clinical risk factors was trained and tested using cross-validation to measure the wound imaging system's accuracy of predicting amputation wound healing.

RESULTS

A total of 22 patients undergoing 25 amputations (10 toe, five transmetatarsal, eight below-knee, and two above-knee amputations) were enrolled. Eleven amputations (44%) were non-healing after 30 days. The machine learning algorithm had 91% sensitivity and 86% specificity for prediction of non-healing amputation sites (area under curve, 0.89).

CONCLUSIONS

This pilot study suggests that a machine learning algorithm combining multispectral wound imaging with patient clinical risk factors may improve prediction of amputation wound healing and therefore decrease the need for reoperation and incidence of delayed healing. We propose that this, in turn, may offer significant cost savings to the patient and health system in addition to decreasing length of stay for patients.

Treatment of acute respiratory distress syndrome from COVID-19 with extracorporeal membrane oxygenation in obstetrical patients

BACKGROUND

Extracorporeal membrane oxygenation therapy has been used as a rescue therapy for patients with severe acute respiratory distress syndrome from COVID-19 who have failed conventional ventilatory strategies. Little is known about the outcome of pregnant and postpartum patients on extracorporeal membrane oxygenation therapy.

OBJECTIVE

To describe the medical and surgical outcomes of pregnant and postpartum patients who were placed on extracorporeal membrane oxygenation therapy for severe acute respiratory distress syndrome from COVID-19.

STUDY DESIGN

A case series reviewing pregnant or postpartum patients with laboratory-confirmed COVID-19 who were placed on extracorporeal membrane oxygenation therapy was conducted within the Baylor Scott & White Healthcare system. The demographics and the medical and surgical outcomes were collected and reviewed.

RESULTS

Between March 2020 and October 2021, 5 pregnant and 5 postpartum women were supported with venovenous extracorporeal membrane oxygenation therapy. The median age was 30 years (interquartile range, 26–33.5) and the median body mass index was 36.6 kg/m² (interquartile range, 29.5–42.0). There was a median of 4.5 days (interquartile range, 1.5–6.8) from admission to any hospital to intubation and 9 days (interquartile range, 7–13) to extracorporeal membrane oxygenation therapy cannulation. One patient had an ischemic stroke, 1 patient had a presumed hemorrhagic stroke, and 9 patients developed bleeding while on extracorporeal membrane oxygenation therapy. Of the 5 pregnant women, 2 patients had intrauterine fetal demise and 3 underwent delivery for maternal hemodynamic instability. The 5 postpartum women were initiated on extracorporeal membrane oxygenation therapy a median of 10 days (interquartile range, 3–11) after delivery. The median length of time on extracorporeal membrane oxygenation therapy was 22 days (interquartile range, 11–31). At the time of the study, there were 2 inpatient mortalities, 6 patients survived to discharge from the extracorporeal membrane oxygenation therapy hospital, and 2 patients were still admitted.

CONCLUSION

There is limited information regarding the use of extracorporeal membrane oxygenation therapy for COVID-19 acute respiratory distress syndrome in obstetrical patients. This case series describes the use of extracorporeal membrane oxygenation therapy and survival in pregnant and postpartum patients with COVID-19.

Surgical Explantation After TAVR Failure: Mid-Term Outcomes From the EXPLANT-TAVR International Registry

OBJECTIVES

The aim of this study was to evaluate clinical characteristics, mechanisms of failure, and outcomes of transcatheter aortic valve replacement (TAVR) explantation.

BACKGROUND

Surgical explantation following TAVR may be required for structural valve degeneration, paravalvular leak, infection, or other reasons. However, in-depth data on indications and outcomes are lacking.

METHODS

Data from a multicenter, international registry (EXPLANT-TAVR) of patients who underwent TAVR explantation were reviewed retrospectively. Explantations performed during the same admission as initial TAVR were excluded. Clinical and echocardiographic outcomes were evaluated. Median follow-up duration was 6.7 months (interquartile range [IQR]: 1.0-18.8 months) after TAVR explantation and was 97.7% complete at 30 days and 86.1% complete at 1 year.

RESULTS

From November 2009 to September 2020, 269 patients across 42 centers with a mean age of 72.7 ± 10.4 years underwent TAVR explantation. About one quarter (25.9%) were deemed low surgical risk at index TAVR, and median Society of Thoracic Surgeons risk at TAVR explantation was 5.6% (IQR: 3.2%-9.6%). The median time to explantation was 11.5 months (IQR: 4.0-32.4 months). Balloon-expandable and self-expanding or mechanically expandable valves accounted for 50.9% and 49.1%, respectively. Indications for explantation included endocarditis (43.1%), structural valve degeneration (20.1%), paravalvular leak (18.2%), and prosthesis-patient mismatch (10.8%). Redo TAVR was not feasible because of unfavorable anatomy in 26.8% of patients. Urgent or emergency cases were performed in 53.1% of patients, aortic root replacement in 13.4%, and 54.6% had concomitant cardiac procedures. Overall survival at last follow-up was 76.1%. In-hospital, 30-day, and 1-year mortality rates were 11.9%, 13.1%, and 28.5%, respectively, and stroke rates were 5.9%, 8.6%, and 18.7%, respectively.

CONCLUSIONS

The EXPLANT-TAVR registry reveals that surgical risks associated with TAVR explantation are not negligible and should be taken into consideration in the lifetime management of aortic stenosis.

Universal preprocedural SARS-CoV-2 testing protocol within a large healthcare system

This research letter details the safety of a universal asymptomatic preprocedural SARS-CoV-2 testing protocol implemented within a large, integrated healthcare system. Among over 145 000 tests administered, fewer than 1 in 1000 patients had subsequent positive tests within 10 days of an initial negative SARS-CoV-2 test. Despite the infrequency of positive tests after negative screening tests, patient-to-provider transmission was documented in five instances.

Long-term outcomes of the Ross procedure in adults

BACKGROUND

The optimal aortic valve replacement for young and middle-aged adults remains elusive. Although several high-volume international centers and surgeons have demonstrated excellent long-term results with the pulmonary autograft (Ross procedure) in adult patients, current guidelines from the United States do not favor this technique. We evaluated long-term clinical and echocardiographic outcomes of adult patients undergoing the Ross procedure at our center.

METHODS

A retrospective review of 225 consecutive adult patients undergoing the Ross procedure was completed. Kaplan-Meier analysis was performed to evaluate overall survival, which was then compared to an age- and sex-matched general population with the log-rank test. Accounting for death as a competing hazard, the cumulative incidence of reintervention and autograft or homograft dysfunction were estimated over the long-term.

RESULTS

Mean age was 42±11 years, and 62 (28%) patients were at least 50 years old. A bicuspid aortic valve was present in 179 (80%) patients. The most common indications for surgery were aortic insufficiency (n=94, 43%), aortic stenosis (n=81, 36%), and mixed etiology (n=46, 21%). In-hospital mortality was 0.9%. Overall survival (with 95% confidence intervals) at 1-, 10- and 20-year was 97.8% (95.9-99.7%), 94.2% (91.0-97.4%), and 81.3% (74.8-88.3%), respectively. Overall survival approximated that of the general population (log-rank P=0.32). The cumulative incidence (with 95% confidence intervals) of any autograft or homograft reintervention at 10-, 15-, and 20-year was 16% (12-20%), 28% (21-35%), and 45% (36-54%), respectively.

CONCLUSIONS

The Ross procedure restores a normal life expectancy to young and middle-aged adults with severe aortic valve disease. The need for reintervention increases steadily during the second decade after the Ross procedure, but less than half of patients require any reintervention for up to 20-year.

Outcomes of Extracorporeal Membrane Oxygenation in Patients With Severe Acute Respiratory Distress Syndrome Caused by COVID-19 Versus Influenza

Background

Extracorporeal membrane oxygenation (ECMO) can be effective for refractory acute respiratory distress syndrome (ARDS) in patients with influenza, but its utility in patients with coronavirus disease 2019 (COVID-19) is uncertain. We compared outcomes of patients with refractory ARDS from COVID-19 and influenza placed on ECMO.

Methods

We conducted a retrospective analysis of 120 patients with refractory ARDS due to COVID-19 or influenza placed on ECMO at 2 referral centers from January 2013 to October 2020. Patient characteristics and clinical outcomes were compared. The primary endpoint was survival to discharge.

Results

Baseline characteristics and comorbidities were similar. During the study period, 53 patients with COVID-19 and 67 patients with influenza were supported. Venovenous ECMO was the predominant initial cannulation strategy in both groups (COVID 92.5% vs influenza 95.5%; P = .5). Survival to hospital discharge was 62.3% (33 of 53 patients) in the COVID-19 group and 64.2% (43 of 67 patients) in the influenza group (P = .8). In patients successfully decannulated, median length of time on ECMO was longer in COVID-19 patients (14 [interquartile range (IQR), 9-30] days vs influenza 10.5 [IQR, 6.8-14.3] days; P = .004). Among patients discharged alive, COVID-19 patients had longer overall length of stay (COVID-19 37 [IQR, 27-62] days vs influenza 13.5 [IQR, 9.3-24] days; P = .007).

Conclusions

In patients with refractory ARDS from COVID-19 or influenza placed on ECMO, there was no significant difference in survival to hospital discharge. In patients surviving to decannulation, the duration of ECMO support and total length of stay were longer in COVID-19 patients.

Long-term outcomes of patients with primary graft dysfunction after cardiac transplantation

OBJECTIVES

The International Society of Heart and Lung Transplantation (ISHLT) criteria for primary graft dysfunction (PGD) after cardiac transplantation have been shown to stratify patient outcomes up to 1 year after transplantation, but scarce data are available regarding outcomes beyond the 1st year. We sought to characterize survival of patients with PGD following cardiac transplantation beyond the 1st year.

METHODS

A retrospective review of consecutive patients undergoing isolated cardiac transplantation at a single centre between 2012 and 2015 was performed. Patients were diagnosed with none, mild, moderate or severe PGD by the ISHLT criteria. Survival was ascertained from the United Network for Organ Sharing database and chart review. Kaplan-Meier curves were plotted to compare survival. The hazard ratio for mortality associated with PGD severity was estimated using Cox-proportional hazards modelling, with a pre-specified conditional survival analysis at 90 days.

RESULTS

A total of 257 consecutive patients underwent cardiac transplantation during the study period, of whom 73 (28%) met ISHLT criteria for PGD: 43 (17%) mild, 12 (5%) moderate and 18 (7%) severe. Patients with moderate or severe PGD had decreased survival up to 5 years after transplantation (log-rank P < 0.001). Landmark analyses demonstrated that patients with moderate or severe PGD were at increased risk of mortality during the first 90-days after transplantation as compared to those with none or mild PGD [hazard ratio (95% confidence interval) 18.9 (7.1-50.5); P < 0.001], but this hazard did not persist beyond 90-days in survivors (P = 0.64).

CONCLUSIONS

A diagnosis of moderate or severe PGD is associated with increased mortality up to 5 years after cardiac transplantation. However, patients with moderate or severe PGD who survive to post-transplantation day 90 are no longer at increased risk for mortality as compared to those with none or mild PGD.

Minimally invasive mitral valve surgery after previous sternotomy: A propensity-matched analysis

BACKGROUND

Although the incidence of mitral valve (MV) surgery after previous open-heart surgery is increasing, there is no consensus regarding the optimal surgical approach. Reoperative MV surgery is most commonly performed via sternotomy (ST). We sought to determine whether minimally-invasive (MIS) reoperative MV surgery is safe and feasible.

METHODS

All patients with a history of ST undergoing MV surgery with or without concomitant tricuspid or atrial fibrillation surgery at a single institution from 2007 to 2018 were retrospectively reviewed. ST and MIS approaches were compared using propensity-matched analysis. The coprimary endpoints were operative mortality and 1-year survival, and secondary endpoints were operative complications and length of stay.

RESULTS

A total of 305 isolated MV reoperations were performed: 199 (65%) MIS and 106 (35%) ST. MIS patients were older than ST patients (71 [63, 76.5] vs. 66 [56, 72] years, p < .01), more likely to have undergone prior coronary artery bypass grafting (57% vs. 27%, p < .01), and less likely to have had prior valve surgery (55% vs. 78%, p < .01). In unmatched comparisons, operative mortality was significantly lower among MIS patients (3.0% vs. 8.5%, p = .04), but 1-year mortality was similar (14.4% vs. 15.6%, p = .8). After propensity matching, 88 pairs had excellent balance across baseline characteristics. Mortality was similar among MIS and ST patients at 30 days (3.4% vs. 8%, p = .19) and 1 year (15.9% vs. 16.5%, p = .9). RBC and fresh frozen plasma transfusions were significantly lower in the MIS group (p < .01).

CONCLUSIONS

A minimally invasive approach is a safe alternative in patients with prior ST undergoing MV surgery.

Systematic Review of Minimally Invasive Surgery for Mitral Valve Infective Endocarditis

OBJECTIVE

The scope of application of minimally invasive mitral valve surgery is expanding. However, the safety and efficacy of minimally invasive mitral valve surgery in the setting of infective endocarditis is not well known. We sought to identify the best evidence available to support a minimally invasive surgical approach for mitral valve infective endocarditis.

METHODS

A systematic review of minimally invasive mitral valve surgery for infective endocarditis was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

A total of 6 manuscripts describing 271 patients were identified. Mean age was 60.4 ± 14.9 years old, and 60.1% patients were male. Mean EuroSCORE II was 24.6 ± 23.2. Mitral valve repair was achieved in 32.4% of cases. The average in-hospital mortality was 9.4%, and average length of hospital stay was 21.6 days. Survival was 89.1% at 30 days, and 1-year survival was 79.3%. Rate of conversion to sternotomy was 1.8%. Postoperative complications included: 6.9% postoperative bleeding, 9.3% new postoperative dialysis, 2.3% postoperative stroke, and 3.4% recurrence of endocarditis. Reoperation over the long-term was required in 9.3% of cases.

CONCLUSIONS

Minimally invasive mitral valve surgery for infective endocarditis has acceptable perioperative morbidity as well as short- and intermediate-term mortality at experienced centers. Minimally invasive mitral valve surgery may be an acceptable alternative approach to infective endocarditis and warrants further study.

Venovenous extracorporeal membrane oxygenation for patients with refractory coronavirus disease 2019 (COVID-19): Multicenter experience of referral hospitals in a large health care system

BACKGROUND

The benefit of extracorporeal membrane oxygenation (ECMO) for patients with severe acute respiratory distress from coronavirus disease 2019 refractory to medical management and lung-protective mechanical ventilation has not been adequately determined.

METHODS

We reviewed the clinical course of 37 patients with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 infection supported by venovenous ECMO at 4 ECMO referral centers within a large health care system. Patient characteristics, progression of hemodynamics and inflammatory markers, and clinical outcomes were evaluated.

RESULTS

The patients had median age of 51 years (interquartile range, 40-59), and 73% were male. Peak plateau pressures, vasopressor requirements, and arterial partial pressure of carbon dioxide all improved with ECMO support. In our patient population, 24 of 37 patients (64.8%) survived to decannulation and 21 of 37 patients (56.8%) survived to discharge. Among patients discharged alive from the ECMO facility, 12 patients were discharged to a long-term acute care or rehabilitation facility, 2 were transferred back to the referring hospital for ventilatory weaning, and 7 were discharged directly home. For patients who were successfully decannulated, median length of time on ECMO was 17 days (interquartile range, 10-33.5).

CONCLUSIONS

Venovenous ECMO represents a useful therapy for patients with refractory severe acute respiratory distress syndrome from coronavirus disease 2019.

How to be an Innovator in Cardiothoracic Surgery

Cardiothoracic surgeons are uniquely and expertly positioned to be innovators. Innovation is an iterative process by which unmet needs are identified, a solution is invented, and the results are implemented. A team approach is required, with participation from a variety of experts including the surgeon-innovator. Innovation can be practiced on a multitude of pathways including basic science, clinical science, and commercialization. Economics realities are often the ultimate determinant in the success or failure of any innovative effort. In this manuscript, we aim to define innovation, describe the innovative process, and demonstrate how these principles can, and should, be enacted by cardiothoracic surgeon-innovators.

Comparison of Frequency of Vascular Complications With Ultrasound-Guided Versus Fluroscopic Roadmap-Guided Femoral Arterial Access in Patients Who Underwent Transcatheter Aortic Valve Implantation

To compare outcomes of ultrasound guidance (USG) versus fluoroscopy roadmap guidance (FG) angiography for femoral artery access in patients who underwent transfemoral (TF) transcatheter aortic valve implantation (TAVI) to determine whether routine USG use was associated with fewer vascular complications. Vascular complications are the most frequent procedural adverse events associated with TAVI. USG may provide a decreased rate of access site complications during vascular access compared with FG. Patients who underwent TF TAVI between July 2012 and July 2017 were reviewed and outcomes were compared. Vascular complications were categorized by Valve Academic Research Consortium-2 criteria and analyzed by a multivariable logistic regression adjusting for potential confounding risk factors including age, gender, body mass index, peripheral vascular disease, Society of Thoracic Surgeons score and sheath to femoral artery ratio. Of the 612 TAVI patients treated, 380 (63.1%) were performed using USG for access. Routine use of USG began in March 2015 and increased over time. Vascular complications occurred in 63 (10.3%) patients and decreased from 20% to 3.9% during the study period. There were fewer vascular complications with USG versus FG (7.9% vs 14.2%, p = 0.014). After adjusting for potential confounding risk factors that included newer valve systems, smaller sheath sizes and lower risk patients, there was still a 49% reduction in vascular complications with USG (odds ratio 0.51, 95% confidence interval 0.29 to 0.88, p = 0.02). In conclusion, USG for TF TAVI was associated with reduced vascular access site complications compared with FG access even after accounting for potential confounding risk factors and should be considered for routine use for TF TAVI.

Safe implementation of enhanced recovery after surgery protocol in transfemoral transcatheter aortic valve replacement

Enhanced recovery after surgery (ERAS) protocols are gaining wide acceptance. We evaluated ERAS protocol implementation in transfemoral transcatheter aortic valve replacement (TAVR) patients. The ERAS protocol included (1) moderate sedation or general anesthesia with on-table extubation, (2) no pulmonary artery or urinary catheters, (3) arterial line removal within 4 hours, (4) no postoperative narcotics, (5) mobilization at 4 hours and ambulation within 8 hours, and (6) antihypertensive reinstitution without nodal blockers. Patients who received TAVR before and after ERAS implementation were compared (N = 121 and N = 368, respectively). The primary endpoint was total hospital length of stay (LOS). ERAS patients had a lower mean Society of Thoracic Surgeons predicted risk of mortality (6.7% vs 7.5%; P = 0.04). Unadjusted analysis demonstrated that ERAS was associated with significantly decreased mean LOS (2.8 vs 4.0 days, P <  0.001), decreased 30-day mortality (0.8% vs 5.0%; P = 0.003), and increased discharge home (90.2% vs 79.3%, P = 0.002) with no increase in 30-day readmission (11.1% vs 14.0%, P = 0.39). After risk adjustment, ERAS patients had a 1.87-day shorter LOS (P = 0.001) and trended toward increased discharge home (odds ratio 1.76, P = 0.078) without increased readmission (odds ratio 0.74, P = 0.4). An ERAS protocol for TAVR is safe and is associated with shorter LOS without increased readmission.

Differential gene expression in patients with primary mitral valve disease: identifying potential therapeutic targets in the era of precision medicine

Primary (degenerative) mitral valve (MV) disease is a result of structural remodeling due to degenerative and adaptive changes of MV tissue. We hypothesized that in patients with primary MV disease undergoing surgery for severe mitral regurgitation (MR), a distinct genetic expression profile within the MV leaflet tissue could be identified as compared with patients without MV disease. Tissue samples from the MV leaflets of 65 patients undergoing MV surgery for MR due to primary MV disease and 4 control cadavers without MV disease were collected and analyzed. MicroRNA transcripts were hybridized to Illumina HumanHT-12 v4 Beadchips. Ingenuity pathway analyses (IPAs) were conducted to provide biological interpretation. Of the approximately 20 000 genes examined, 4092 (20%) were differentially expressed between patients with primary MV disease and normal controls (false discovery rate<0.05). The differentially expressed genes could be clustered into five regulator effect networks from the Ingenuity Knowledge IPA database with a consistency score of >6. These five networks have been previously implicated in pathophysiological cardiac abnormalities, including inhibited contractility of the heart and fatty acid oxidation as well as activation of apoptosis of smooth muscle cells, cardiac degeneration, and hypertrophy of cardiac cells. MV tissue in patients with primary MV disease demonstrated distinct genetic expression patterns as compared with normal controls. Further studies are necessary to determine whether the molecular pathways identified in this experiment may represent potential therapeutic targets to prevent degeneration of MV tissue leading to severe MR.

Prospective Evaluation of a Blood Transfusion Protocol for Patients Undergoing Cardiac Operations

BACKGROUND

The Society of Thoracic Surgeons clinical practice guidelines recommend the creation of an interdisciplinary blood management team to implement protocols for improved blood transfusion practices. We report our center's prospective evaluation of a blood transfusion protocol.

METHODS

An interdisciplinary blood management team developed protocols for transfusion of packed red blood cells, fresh frozen plasma, platelets, and cryoprecipitate. The protocols were prospectively evaluated by tracking transfusions administered to consecutive patients undergoing cardiac operations, and the primary outcome of interest was the mean number of adjusted units of blood product transfused per patient. Protocol implementation phases were separated by washout phases to control for a potential Hawthorne effect associated with protocol implementation. Protocol compliance was also assessed.

RESULTS

A total of 1441 patients underwent cardiac operations during the 16-month study period. Although there was no statistically significant reduction in transfusions with an unadjusted analysis, there was a significant trend toward a reduction of the mean adjusted total units transfused per patient over the course of the study period (P < .001). The mean adjusted total units transfused per patient were significantly less during the second washout phase (2.8 units; 95% confidence interval [CI], 2.3-3.3) and second protocol phase (2.8 units; 95% CI, 2.32-3.27) compared with the initial baseline survey phase (3.6 units, 95% CI, 3.1-4.1; P < .05 for both comparisons). Only 55.2% of all units were transfused in compliance to the implemented protocols: platelets, 46.8%; cryoprecipitate, 32.1%; packed red blood cells, 60.7%; and fresh frozen plasma, 53.6%.

CONCLUSIONS

During a prospective evaluation of blood transfusion protocols, a risk-adjusted analysis demonstrated a reduction in transfusions despite poor protocol compliance.

Coronary artery bypass grafting-fifty years of quality initiatives since Favaloro

Coronary artery bypass grafting (CABG) remains one of the most commonly performed major surgical procedures worldwide and the most common procedure performed by cardiac surgeons. Rene Favaloro is widely credited with recognizing the true potential of CABG and subsequently popularizing the technique in a broad manner. Since the era of Favaloro in the late 1960s, the evolution of CABG can be understood through a series of quality initiatives that have defined which patients can benefit from the procedure and via which technique(s) they will derive the greatest benefit. Herein, we will review some of the key developments in CABG over the last 50 years with a focus on ongoing quality initiatives that will continue to refine the optimal applications and outcomes of CABG for the next 50 years.

Burn-injured tissue detection for debridement surgery through the combination of non-invasive optical imaging techniques

The process of burn debridement is a challenging technique requiring significant skills to identify the regions that need excision and their appropriate excision depths. In order to assist surgeons, a machine learning tool is being developed to provide a quantitative assessment of burn-injured tissue. This paper presents three non-invasive optical imaging techniques capable of distinguishing four kinds of tissue-healthy skin, viable wound bed, shallow burn, and deep burn-during serial burn debridement in a porcine model. All combinations of these three techniques have been studied through a k-fold cross-validation method. In terms of global performance, the combination of all three techniques significantly improves the classification accuracy with respect to just one technique, from 0.42 up to more than 0.76. Furthermore, a non-linear spatial filtering based on the mode of a small neighborhood has been applied as a post-processing technique, in order to improve the performance of the classification. Using this technique, the global accuracy reaches a value close to 0.78 and, for some particular tissues and combination of techniques, the accuracy improves by 13%.

Description of a Method to Obtain Complete One-Year Follow-Up in the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy Registry

The Centers for Medicare and Medicaid Services National Coverage Determination requires centers performing transcatheter aortic valve implantation (TAVI) to report clinical outcomes up to 1 year. Many sites encounter challenges in obtaining complete 1-year follow-up. We report our process to address this challenge. A multidisciplinary process involving clinical personnel, data and quality managers, and research coordinators was initiated to collect TAVI data at baseline, 30 days, and 1 year. This process included (1) planned clinical follow-up of all patients at 30 days and 1 year; (2) query of health-care system-wide integrated data warehouse (IDW) to ascertain last date of clinical contact within the system for all patients; (3) online obituary search, cross-referencing for unique patient identifiers to determine if mortality occurred in remaining unknown patients; and (4) phone calls to remaining unknown patients or patients' families. Between January 2012 and December 2016, 744 patients underwent TAVI. All 744 patients were eligible for 30-day follow-up and 546 were eligible for 1-year follow-up. At routine clinical follow-up of 22 of 744 (3%) patients at 30 days and 180 of 546 (33%) patients at 1 year had unknown survival status. The integrated data warehouse query confirmed status-alive for an additional 1 of 22 patients at 30 days (55%) and 91 of 180 patients at 1 year (51%). Obituaries were identified for 23 of 180 additional patients at 1 year (13%). Phone contact identified the remaining unknown patients at 30 days and 1 year, resulting in 100% known survival status for patients at 30 days (744 of 744) and at 1 year (546 of 546). In conclusion, using a comprehensive approach, we were able to determine survival status in 100% of patients who underwent TAVI.

Surgical Closure of the Left Atrial Appendage: The Past, The Present, The Future

Occlusion of the left atrial appendage (LAA) may protect against stroke in patients with atrial fibrillation. While percutaneous LAA closure devices have demonstrated efficacy in stroke reduction, surgical LAA occlusion has been performed with mixed results to date. Although surgical exclusion via internal sutures or noncutting stapler is ineffective due to recanalization of the LAA, surgical excision and certain exclusion devices including the AtriClip device are effective methods to achieve complete closure of the LAA. No data currently exists to support routine, prophylactic LAA closure at the time of cardiac surgery, but this practice may benefit certain patients at high risk for stroke. The currently enrolling Left Atrial Appendage Occlusion Study (LAAOS) III is the largest study to date designed to assess the efficacy of LAA occlusion for stroke prevention. The results of this trial will inform future clinical practice regarding stroke prevention with surgical LAA occlusion for patients with atrial fibrillation. Meanwhile, the ATLAS trial is investigating the efficacy of LAA occlusion in surgical patients who do not have atrial fibrillation but are at increased risk for developing it post-operatively.