Minimally invasive thymectomy approaches 'preferable' in most myasthenia gravis cases
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Researchers observed a significant difference in the rate of complete stable remission among several surgical methods for thymectomy in myasthenia gravis, according to results of a meta-analysis published in Neurology.
“Although until recently there were no randomized trials evaluating the benefit of thymectomy, multiple case-series have been published over many years suggesting a 40-90% ‘remission’ rate (variably defined) following thymectomy, whereas only 10-20% of patients achieved ‘remission’ with medical therapy alone,” Paola Solis-Pazmino, MD, a visiting scholar in the division of thoracic surgery, department of cardiothoracic surgery, at Stanford University School of Medicine, and colleagues wrote. “The only prospective randomized trial on this topic — the Thymectomy Trial in Non-Thymomatous Myasthenia Gravis Patients Receiving Prednisone (MGTX) published in 2016 — definitively
demonstrated superiority of thymectomy and prednisone compared to prednisone alone at 3 and 5 years post-surgery.”
In the current study, the researchers sought to assess the effectiveness of various surgical methods for conducting thymectomy, or the removal of the thymus gland, among individuals with myasthenia gravis (MG), with emphasis on long-term outcomes and complete stable remission, which they chose because “many have felt it to be the most reliable, least bias-prone outcome,” according to the study results. In the meta-analysis, they included 12 cohort studies and one randomized clinical trial, which contained a total of 1,598 patients, that provided comparative data on surgical approaches to thymectomy and reported complete stable remission with a minimum of 3 years mean follow-up.
Results showed comparable complete stable remission from MG following video-assisted thoracoscopic surgery (VATS) extended for both basic (RR = 1; P = 1; 95% CI, 0.39-2.58) and extended (RR = 0.96; P = .74; 95% CI, 0.72-1.27) transsternal approaches, as well as extended transsternal compared with combined transcervical-subxiphoid (RR = 1.08; P = .62; 95% CI, 0.8-1.44) approaches, at 3 years. Follow-up through 9 years showed statistical equivalence between VATS extended approaches and extended transsternal approaches (RR = 1.51; P = .05; 95% CI, 0.99-2.3). Solis-Pazmino and colleagues observed the only significant difference in complete stable remission rate with a traditional open vs. a minimally invasive approach at 10 years when they compared the no-longer-used basic transcervical approach and the extended transsternal approach (RR = 0.4; P = .01; 95% CI, 0.2-0.8).
Complications were reported in five in the 13 studies, according to the study results. While the remaining eight studies reported “some subset” of complications — including pneumonia, exacerbation of MG, atelectasis, arrhythmia and wound infection — the only difference to reach statistical significance “in this limited dataset” was the rate of arrhythmia between the VATS extended technique and the extended transsternal operation, with a decreased risk for arrhythmia using VATS (RR = 0.10; 95% CI, 0.01-0.72), the researchers found.
“This difference remained significant when we pooled all of the minimally invasive techniques and compared their complication rates with that of all of the transsternal techniques,” Solis-Pazmino and colleagues wrote.
The results of this meta-analysis suggest that neurologists “should feel comfortable” referring patients with MG to experienced thymic surgeons who prefer extended, minimally invasive thymectomy approaches, such as extended VATS. The researchers also noted that the minimally invasive techniques can achieve the same complete stable remission rates as the extended transsternal technique, which they described as “a reasonable option” with “excellent” rates of complete stable remission.
“The benefits of minimally invasive approaches (in most studies) in duration and severity of postoperative discomfort and disability, postoperative complications and costs render them preferable in most MG patients who have an appropriate body habitus,” the researchers wrote. “Absolute certainty on the equivalence of extended minimally invasive thymectomy approaches to extended transsternal thymectomy in MG would require a prospective randomized trial. This is highly unlikely to be executed given the proven and inherent difficulties in [randomly assigning] patients to minimally invasive vs. traditional, ‘open’ surgical approaches.”
Perspective
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Ericka Wong, MD
Thymectomy has been shown to benefit patients with acetylcholine receptor antibody-positive generalized MG. The preferred surgical approach for thymectomy in MG varies widely, and the MGTX study (which is referenced in this paper) stipulated that extended transsternal thymectomy be performed.
However, shorter recovery time as well as lower complication rates of minimally invasive techniques makes it appealing to both physicians and their patients. Solis-Pazmino and colleagues performed a meta-analysis on literature comparing thymectomy techniques in patients with MG.
Although there were limitations of the data available, several important findings were gleaned from their analysis. Of most clinical relevance is the finding that there was no difference in complete stable remission rates achieved by extended VATS thymectomy vs. extended transsternal thymectomy. The study also highlights the importance of the expertise of the surgeon, regardless of their technique. Neurologists can be more confident considering extended minimally invasive thymectomy approaches when referring patients for surgery.
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