Research Spotlight

El Chami, M., R. C. Kowal, K. Soejima, P. Ritter, G. Z. Duray, P. Neuzil, L. Mont, A. Kypta, V. Sagi, J. H. Hudnall, K. Stromberg and D. Reynolds (2017). “Impact of operator experience and training strategy on procedural outcomes with leadless pacing: Insights from the micra transcatheter pacing study.” Pacing Clin Electrophysiol: Apr [Epub ahead of print].

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BACKGROUND: Leadless pacemaker systems have been designed to avoid the need for a pocket and transvenous lead. However, delivery of this therapy requires a new catheter-based procedure. This study evaluates the role of operator experience and different training strategies on procedural outcomes. METHODS: A total of 726 patients underwent implant attempt with the Micra transcatheter pacing system (TPS) by 94 operators trained in a teaching laboratory using a simulator, cadaver, and large animal models (lab training) or locally at the hospital with simulator/demo model and proctorship (hospital training). Procedure success, procedure duration, fluoroscopy time, and safety outcomes were compared between training methods and experience (implant case number). RESULTS: The Micra TPS procedure was successful in 99.2% of attempts and did not differ between the 55 operators trained in the lab setting and the 39 operators trained locally at the hospital (P = 0.189). Implant case number was also not a determinant of procedural success (P = 0.456). Each operator performed between 1 and 55 procedures. Procedure time and fluoroscopy duration decreased by 2.3% (P = 0.002) and 3.2% (P<0.001) compared to the previous case. Major complication rate and pericardial effusion rate were not associated with case number (P = 0.755 and P = 0.620, respectively). There were no differences in the safety outcomes by training method. CONCLUSIONS: Among a large group of operators, implantation success was high regardless of experience. While procedure duration and fluoroscopy times decreased with implant number, complications were low and not associated with case number. Procedure and safety outcomes were similar between distinct training methodologies.

Mehta, R. H., J. D. Leimberger, S. van Diepen, J. Meza, A. Wang, R. Jankowich, R. W. Harrison, D. Hay, S. Fremes, A. Duncan, E. G. Soltesz, J. Luber, S. Park, M. Argenziano, E. Murphy, R. Marcel, D. Kalavrouziotis, D. Nagpal, J. Bozinovski, W. Toller, M. Heringlake, S. G. Goodman, J. H. Levy, R. A. Harrington, K. J. Anstrom and J. H. Alexander (2017). “Levosimendan in Patients with Left Ventricular Dysfunction Undergoing Cardiac Surgery.” N Engl J Med: 2017 Mar [Epub ahead of print].

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Background Levosimendan is an inotropic agent that has been shown in small studies to prevent or treat the low cardiac output syndrome after cardiac surgery. Methods In a multicenter, randomized, placebo-controlled, phase 3 trial, we evaluated the efficacy and safety of levosimendan in patients with a left ventricular ejection fraction of 35% or less who were undergoing cardiac surgery with the use of cardiopulmonary bypass. Patients were randomly assigned to receive either intravenous levosimendan (at a dose of 0.2 mug per kilogram of body weight per minute for 1 hour, followed by a dose of 0.1 mug per kilogram per minute for 23 hours) or placebo, with the infusion started before surgery. The two primary end points were a four-component composite of death through day 30, renal-replacement therapy through day 30, perioperative myocardial infarction through day 5, or use of a mechanical cardiac assist device through day 5; and a two-component composite of death through day 30 or use of a mechanical cardiac assist device through day 5. Results A total of 882 patients underwent randomization, 849 of whom received levosimendan or placebo and were included in the modified intention-to-treat population. The four-component primary end point occurred in 105 of 428 patients (24.5%) assigned to receive levosimendan and in 103 of 421 (24.5%) assigned to receive placebo (adjusted odds ratio, 1.00; 99% confidence interval [CI], 0.66 to 1.54; P=0.98). The two-component primary end point occurred in 56 patients (13.1%) assigned to receive levosimendan and in 48 (11.4%) assigned to receive placebo (adjusted odds ratio, 1.18; 96% CI, 0.76 to 1.82; P=0.45). The rate of adverse events did not differ significantly between the two groups. Conclusions Prophylactic levosimendan did not result in a rate of the short-term composite end point of death, renal-replacement therapy, perioperative myocardial infarction, or use of a mechanical cardiac assist device that was lower than the rate with placebo among patients with a reduced left ventricular ejection fraction who were undergoing cardiac surgery with the use of cardiopulmonary bypass.

Moreland, A. M., C. A. Santa Ana, J. R. Asplin, J. A. Kuhn, R. P. Holmes, J. A. Cole, E. A. Odstrcil, T. G. Van Dinter, Jr., J. G. Martinez and J. S. Fordtran (2017). “Steatorrhea and Hyperoxaluria in Severely Obese Patients Before and After Roux-en-Y Gastric Bypass.” Gastroenterology 152(5): 1055-1067.e1053.

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BACKGROUND AND AIMS: Hyperoxaluria after Roux-en-Y gastric bypass (RYGB) is generally attributed to fat malabsorption. If hyperoxaluria is indeed caused by fat malabsorption, magnitudes of hyperoxaluria and steatorrhea should correlate. Severely obese patients, prior to bypass, ingest excess dietary fat that can produce hyperphagic steatorrhea. The primary objective of the study was to determine whether urine oxalate excretion correlates with elements of fat balance in severely obese patients before and after RYGB. METHODS: Fat balance and urine oxalate excretion were measured simultaneously in 26 severely obese patients before and 1 year after RYGB, while patients consumed their usual diet. At these time points, stool and urine samples were collected. Steatorrhea and hyperoxaluria were defined as fecal fat >7 g/day and urine oxalate >40 mg/day. Differences were evaluated using paired 2-tailed t tests. RESULTS: Prior to RYGB, 12 of 26 patients had mild to moderate steatorrhea. Average urine oxalate excretion was 61 mg/day; there was no correlation between fecal fat and urine oxalate excretion. After RYGB, 24 of 26 patients had steatorrhea and urine oxalate excretion averaged 69 mg/day, with a positive correlation between fecal fat and urine oxalate excretions (r = 0.71, P < .001). For each 10 g/day increase in fecal fat output, fecal water excretion increased only 46 mL/day. CONCLUSIONS: Steatorrhea and hyperoxaluria were common in obese patients before bypass, but hyperoxaluria was not caused by excess unabsorbed fatty acids. Hyperphagia, obesity, or metabolic syndrome could have produced this previously unrecognized hyperoxaluric state by stimulating absorption or endogenous synthesis of oxalate. Hyperoxaluria after RYGB correlated with steatorrhea and was presumably caused by excess fatty acids in the intestinal lumen. Because post-bypass steatorrhea caused little increase in fecal water excretion, most patients with steatorrhea did not consider themselves to have diarrhea. Before and after RYGB, high oxalate intake contributed to the severity of hyperoxaluria.

Leeds, S. G., L. Wooley, G. Sankaranarayanan, Y. Daoud, J. Fleshman and S. Chauhan (2017). “Learning Curve Associated With an Automated Laparoscopic Suturing Device Compared With Laparoscopic Suturing.” Surg Innov 24(2): 109-114.

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BACKGROUND: Laparoscopic suturing has proved to be a challenging skill to master which may prevent surgical procedures from being started, or completed, in a minimally invasive fashion. The aim of this study is to compare the learning curves between traditional laparoscopic techniques with a novel suturing device. METHODS: In this prospective single blinded nonrandomized controlled crossover study, we recruited 19 general surgery residents ranging from beginner (PGY1-2, n = 12) to advanced beginner (PGY3-5, n = 7). They were assigned to perform a knot tying and suturing task using either Endo360 or traditional laparoscopic technique (TLT) with needle holders before crossing over to the other method. The proficiency standards were developed by collecting the data for task completion time (TCT in seconds), dots on target (DoT in numbers), and total deviation (D in mm) on 5 expert attending surgeons (mean +/- 2SD). The test subjects were “proficient” when they reached these standards 2 consecutive times. RESULTS: Number of attempts to complete the task was collected for Endo360 and TLT. A significant difference was observed between mean number of attempts to reach proficiency for Endo360 versus TLT ( P = .0027) in both groups combined, but this was not statistically significant in the advanced beginner group. TCT was examined for both methods and demonstrated significantly less time to complete the task for Endo360 versus TLT ( P < .0001). There were significantly less DoT for Endo360 as compared with TLT ( P < .0001), which was also associated with significantly less D ( P < .0001) indicating lower accuracy with Endo360. However, no significant difference was observed between the groups for increasing number of trials for both DoT and D. CONCLUSIONS: This novel suturing device showed a shorter learning curve with regard to number of attempts to complete a task for the beginner group in our study, but matched the learning curve in the advanced beginner group. With regard to time to complete the task, the device was faster in both groups.

Packer, M. (2017). “Let Us Not Forget the Long-term Safety Concerns of Sacubitril/Valsartan-Reply.” JAMA Cardiol: 2017 Mar [Epub ahead of print].

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The letter by McCarthy and McEvoy illustrates the distinctive process that permeates the thinking of physicians who treat heart failure in contrast to those who treat cancer. Oncologists enthusiastically use drugs in high doses in the hope that they might prolong life, knowing with certainty that the drugs cause serious adverse effects. In contrast, cardiologists hesitate to use a drug that has been demonstrated (beyond a reasonable doubt) to prolong life simply because someone raises the hypothetical concern about an unobserved adverse effect that might occur 10 to 20 years later. McCarthy and McEvoy make reference to the concerns of the US Food and Drug Administration about the risk of dementia with sacubitril/valsartan; fortunately, their position is far more reassuring than the authors of the letter have conveyed. A comprehensive summary of the regulatory position on the safety of the drug has recently been published.