Sameer A. Hirji

Extent, location, and clinical significance of non-infarct-related coronary artery disease among patients with ST-elevation myocardial infarction

IMPORTANCE Little information exists about the anatomical characteristics and clinical relevance of non-infarct-related artery (IRA) disease among patients with ST-segment elevation myocardial infarction (STEMI). OBJECTIVES To investigate the incidence, extent, and location of obstructive non-IRA disease and compare 30-day mortality according to the presence of non-IRA disease in patients with STEMI. DESIGN, SETTING, AND PARTICIPANTS Retrospective study of patients pooled from a convenience sample of 8 independent, international, randomized STEMI clinical trials published between 1993 and 2007. Follow-up varied from 1 month to 1 year. Among 68,765 patients enrolled in the trials, 28,282 patients with valid angiographic information were included in this analysis. Obstructive coronary artery disease was defined as stenosis of 50% or more of the diameter of a major epicardial artery. To assess the generalizability of trial-based results, external validation was performed using observational data for patients with STEMI from the Korea Acute Myocardial Infarction Registry (KAMIR) (between November 1, 2005, and December 31, 2013; n = 18,217) and the Duke Cardiovascular Databank (between January 1, 2005, and December 31, 2012; n = 1812). MAIN OUTCOMES AND MEASURES Thirty-day mortality following STEMI. RESULTS Overall, 52.8% (14,929 patients) had obstructive non-IRA disease; 29.6% involved 1 vessel and 18.8% involved 2 vessels. There was no substantial difference in the extent and distribution of non-IRA disease according to the IRA territory. Unadjusted and adjusted rates of 30-day mortality were significantly higher in patients with non-IRA disease than in those without non-IRA disease (unadjusted, 4.3% vs 1.7%, respectively; risk difference, 2.7% [95% CI, 2.3% to 3.0%], P < .001; and adjusted, 3.3% vs 1.9%, respectively; risk difference, 1.4% [95% CI, 1.0% to 1.8%], P < .001). The overall prevalence and association of non-IRA disease with 30-day mortality was consistent with findings from the KAMIR registry (adjusted, 3.6% for patients with non-IRA disease vs 2.5% in those without it; risk difference, 1.1% [95% CI, 0.6% to 1.7%]; P < .001), but not with the Duke database (adjusted, 4.7% with non-IRA disease vs 4.3% without it; risk difference, 0.4% [95% CI, -1.4% to 2.2%], P = .65). CONCLUSIONS AND RELEVANCE In a retrospective pooled analysis of 8 clinical trials, obstructive non-IRA disease was common among patients presenting with STEMI, and was associated with a modest statistically significant increase in 30-day mortality. These findings require confirmation in prospectively designed studies, but raise questions about the appropriateness and timing of non-IRA revascularization in patients with STEMI.

Bridge to lung transplantation and rescue post-transplant: the expanding role of extracorporeal membrane oxygenation

Over the last several decades, the growth of lung transplantation has been hindered by a much higher demand for donor lungs than can be supplied, leading to considerable waiting time and mortality among patients waiting for transplant. This has led to the search for an alternative bridging strategy in patients with end-stage lung disease. The use of extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation as well as a rescue strategy post-transplant for primary graft dysfunction (PGD) has been studied previously, however due to initially poor outcomes, its use was not heavily instituted. In recent years, with significant improvement in technologies, several single and multi-center studies have shown promising outcomes related to the use of ECMO as a bridging strategy as well as a therapy for patients suffering from PGD post-transplant. These results have challenged our current notion on ECMO use and hence forced us to reexamine the utility, efficacy and safety of ECMO in conjunction with lung transplantation. Through this review, we will address the various aspects related to ECMO use as a bridge to lung transplantation as well as a rescue post-transplant in the treatment of PGD. We will emphasize newer technologies related to ECMO use, examine recent observational studies and randomized trials of ECMO use before and after lung transplantation, and reflect upon our own institutional experience with the use of ECMO in these difficult clinical situations.

Single lung transplantation in the United States: What happens to the other lung?

BACKGROUND This study assessed treatment patterns and examined organ utilization in the setting of single-lung transplantation (SLT). METHODS The United Network for Organ Sharing database was queried for all SLTs performed from 1987 to 2011. Trends in utilization of the second donor lung were assessed, both from recipient and donor perspectives. Donors were stratified into 2 groups: those donating both lungs and those donating only 1 lung. Independent predictors of using only 1 donor lung were identified using multivariable logistic regression. RESULTS We identified 10,361 SLTs originating from 7,232 unique donors. Of these donors, both lungs were used in only 3,129 (43.3%), resulting in more than 200 second donor lungs going unused annually since 2005, with no significant increase in use over time (p = 0.95). After adjustment, donor characteristics predicting the second donor lung going unused included B/AB blood groups (adjusted odds ratio [AOR]: 1.69 and 2.62, respectively; p < 0.001), smaller body surface area (AOR, 1.30; p = 0.02), lower donor partial pressure of arterial oxygen (AOR, 0.90 per 50 mm Hg increase; p < 0.001), pulmonary infection (AOR, 1.15; p = 0.04), extended criteria donor status (AOR, 1.66; p < 0.001), and death caused by head trauma (AOR, 1.57; p < 0.001) or anoxia (AOR, 1.53; p = 0.001). CONCLUSIONS Among donors for SLT, less than half of all cases led to use of the second donor lung. Although anatomic, infectious, or other pathophysiologic issues prohibit 100% utilization, more aggressive donor matching efforts may be a simple method of increasing the utilization of this scarce resource, particularly for less common blood types.

What Is the Optimal Transplant for Older Patients With Idiopathic Pulmonary Fibrosis

BACKGROUND There is controversy regarding the optimal type of lung transplant--single orthotopic lung transplantation (SOLT) versus bilateral orthotopic lung transplantation (BOLT)--for patients with idiopathic pulmonary fibrosis. We performed this study to determine which type of transplant is more appropriate for older patients with this condition. METHODS We conducted a review of the United Network for Organ Sharing database from 2005 to 2013 for patients aged 65 years or more with idiopathic pulmonary fibrosis. A 1:1 nearest-neighbor propensity match was utilized to determine differences in survival by transplant procedure type (SOLT versus BOLT). Logistic regression modeling taking into account interaction terms between prespecified variables and the type of transplant was utilized to determine variables that altered the survival outcomes associated with SOLT versus BOLT. RESULTS Of 1,564 patients who met study criteria, 521 (33.3%) received BOLT. After propensity matching 498 BOLT recipients to 498 SOLT recipients, BOLT was associated with a significantly improved 5-year survival (48.7% versus 35.2%, p < 0.01). However, the mortality hazard associated with BOLT varied from a nonsignificant reduction in survival within 3 months after transplant (hazard ratio 1.24, 95% confidence interval: 0.80 to 1.93) to a significant survival benefit for patients who survived beyond 1 year (hazard ratio 0.64, 95% confidence interval: 0.47 to 0.86). Functional status was also found to be a significant predictor of the survival benefit associated with BOLT. CONCLUSIONS Bilateral orthotopic lung transplantation is associated with significantly improved survival over SOLT for older patients with idiopathic pulmonary fibrosis, driven by a late survival benefit from bilateral transplantation. However, patients with a reduced preoperative functional status do not appear to derive a similar benefit from bilateral transplantation.

Assessment of different threshold preoperative glomerular filtration rates as markers of outcomes in lung transplantation.

BACKGROUND The evidence behind the widely used pre-lung transplant glomerular filtration rate (GFR) cutoff of 50 mL/min per 1.73 m2 is limited. This study reviews data from a large cohort to assess outcomes associated with this historical cutoff and to estimate other possible cutoffs that might be appropriate in lung transplantation. METHODS We conducted a retrospective cohort analysis of lung recipients at a single center. Recursive partitioning and receiver operating characteristics analysis were used to estimate other potential GFR cutoffs with 1-year mortality as the outcome. Postoperative outcomes around the various cutoffs, including survival, acute kidney injury, and dialysis, were assessed using χ2, Kaplan-Meier, and Cox regression methods. RESULTS A total of 794 lung recipients met study inclusion criteria. Compared with 778 patients with GFR 50 mL/min per 1.73 m2 or greater at time of transplant, 16 patients with GFR below this cutoff were older and more likely to have restrictive disease. One-year mortality below the cutoff was 31.3% compared with 15.1% above the cutoff (p=0.021). Recursive partitioning estimated potential GFR cutoff values between 46 and 61 mL/min per 1.73 m2. Patients with GFR below these cutoffs were at significantly higher risk for adverse outcomes (p<0.05). Receiver operating characteristics analysis was less successful at identifying meaningful cutoff values with areas under the curve approximately 0.5. CONCLUSIONS Study results support the practice of requiring candidate GFR 50 mL/min per 1.73 m2 or greater for lung transplantation. Future work should focus on reproducing the analysis in a larger cohort of patients including more individuals with low GFR.

Determining eligibility for lung transplantation: A nationwide assessment of the cutoff glomerular filtration rate

BACKGROUND Historical concerns about lung transplantation in patients with a glomerular filtration rate (GFR) ≤ 50 ml/min/1.73 m(2) have not been validated. We hypothesize that a pre-transplant GFR ≤ 50 ml/min/1.73 m(2) represents a high mortality risk, especially in the setting of acute GFR decline. In addition, we explore the potential for improved risk stratification using a statistically derivable alternative cutoff. METHODS Adult, primary, lung recipients in the United Network for Organ Sharing database were analyzed (October 1987 to December 2011). Recursive partitioning identified the GFR value that provides maximal separation in 1-year mortality. Survival over/under the cutoffs was compared using stratified log-rank, Cox, and Kaplan-Meier methods, before and after 1:2 propensity score matching. RESULTS Median GFR at time of transplant for 19,425 study patients was 94.2 ml/min/1.73 m(2) (quartile 1-quartile, 2 76.9-105.9 ml/min/1.73 m(2)). Recursive partitioning identified a GFR of 40.2 ml/min/1.73 m(2) as the ideal inflection point for predicting 1-year survival. Cutoffs demonstrated statistically significant effects on survival after 840 patients with a GFR ≤ 50 ml/min/1.73 m(2) (hazard ratio, 1.28; 95% confidence interval, 1.15-1.43) and 401 patients with a GFR ≤ 40.2 ml/min/1.73 m(2) (hazard ratio, 1.57; 95% confidence interval, 1.36-1.83) were matched with high GFR controls (p < 0.001). In 13,509 patients with available GFR at the time of listing and transplant, a pre-transplant GFR decline of ≥ 50% from baseline was associated with worse survival (p < 0.001). CONCLUSIONS A pre-transplant GFR ≤ 50 ml/min/1.73 m(2) is associated with decreased survival. However, patients with GFR between 40 and 50 ml/min/1.73 m(2) do not suffer excessive post-transplant mortality and should not be automatically excluded from listing. Notably, outcomes are worse in patients with poor renal function and concomitant pre-transplant GFR decline. Strategies should be devised to detect and manage interval renal deterioration before lung transplantation.

Cardiac troponin release following hybrid coronary revascularization versus off-pump coronary artery bypass surgery

OBJECTIVES Cardiac ischaemic marker release is associated with adverse clinical outcomes after cardiac surgery. We sought to compare the release of cardiac troponin I (cTnI) after hybrid coronary revascularization (HCR) with off-pump coronary artery bypass surgery (OPCAB). METHODS Using data from a prospective single-centre registry, we compared cTnI measured at postoperative day 1 following one-stage HCR and OPCAB among patients with normal baseline cTnI. Multivariable linear regression analysis was used to adjust for variables that may have influenced cardiac marker release other than the used revascularization strategy. RESULTS Sixty-five consecutive patients underwent elective HCR (n = 33) or OPCAB (n = 32). Overall, no differences were seen in comorbidities, CABG risk scores and the lesion-specific SYNTAX score. Procedural complications were lower (15.2 vs 34.4%, P = 0.072), but 30-day and 1-year clinical outcomes (death, myocardial infarction, and repeat revascularization) were similar between the two groups (3.0 vs 3.1% and 9.1 vs 6.2%, respectively). Post-procedural cTnI release measured at 24 h after surgery was significantly lower following HCR compared with OPCAB [ratio of upper reference level URL: median: 3.5, interquartile range (IQR): 0.8-9.1 vs 12.8, IQR: 6.9-21.8, P = 0.001]. After adjusting for potential confounders, HCR was associated, on average, with cTnI less than half (46%) compared with CABG (P <0.0001). CONCLUSIONS HCR is associated with lower postoperative cTn release, compared with OPCAB. Further research into the clinical implications of this finding is warranted.

Hyperbaric Oxygen Therapy for Treatment of Neurologic Sequela After Atrioesophageal Fistula

Atrioesophageal fistula (AEF) is a rare complication after radiofrequency ablation for atrial fibrillation but is associated with high mortality, usually due to sepsis or neurologic injury. We report the case of a patient who presented with an AEF and dense neurologic deficits who had complete neurologic recovery after management with emergent surgical repair without the use of cardiopulmonary bypass and with implementation of postoperative hyperbaric oxygen therapy.

Bridge to long-term mechanical circulatory support with a left ventricular assist device: novel use of transcatheter aortic valve replacement.

We describe the use of transcatheter aortic valve replacement to allow for bridging to a left ventricular assist device in a patient with end-stage heart failure, secondary to nonischemic cardiomyopathy and severe bioprosthetic aortic valve regurgitation.

Outcomes of repeat mitral valve replacement in patients with prior mitral surgery: A benchmark for transcatheter approaches

Objectives With the emergence of transcatheter mitral valve‐in‐valve/ring replacement for deteriorated bioprostheses or failed repair, comparative clinical benchmarks for surgical repeat mitral valve replacement (re‐MVR) are needed. We present in‐hospital and survival outcomes of a 24‐year experience with re‐MVR. Methods From January 1992 to June 2015, 520 adult patients underwent re‐MVR; 273 had undergone prior mitral valve repair (pMVP) and 247 had undergone prior MVR (pMVR). A benchmark cohort of isolated re‐MVR was defined based on potential eligibility for transcatheter mitral valve‐in‐valve/ring replacement, resulting in 73 pMVPs with previous annuloplasty rings and 74 pMVRs with previous bioprosthetic valves for comparison. Results For the entire cohort, mean age was 64 ± 12 years for pMVP patients and 63 ± 15 years for pMVR patients (P = .281), which was similar for the benchmark cohort. Overall operative mortality was 14 out of 273 (5%) for pMVP versus 23 out of 247 (9%) for pMVR (P = .087). There were 3 operative deaths (4.1%) in both groups of the benchmark cohort (P = 1.0). For the benchmark cohort, median time to reoperation was 9.8 years for pMVP and 9.1 years for pMVR. Cox proportional hazard analysis showed that chronic kidney disease (hazard ratio [HR], 2.47; 95% CI, 1.77‐3.44), endocarditis (HR, 1.49; 95% CI, 1.07‐2.07), pMVR (HR, 1.45; 95% CI, 1.12‐1.89), early reoperation ≤ 1 year (HR, 1.49; 95% CI, 1.02‐2.17), and age (HR, 1.04/y; 95% CI, 1.03‐1.05) were associated with decreased survival after re‐MVR. Conclusions A re‐MVR is a high‐risk operation, but in carefully selected patients such as our benchmark population, it can be performed with acceptable results. Patients undergoing pMVP also have better long‐term survival compared with patients undergoing pMVR. These results will serve as a benchmark for transcatheter mitral valve‐in‐valve/ring replacement.