Examiner.com posted “Reviewing the data: Lung surgery after cardiac stents” by Kristin Eckland.
Lung Surgery after cardiac stents: part II
In the first part of our two part series, we reviewed basic cardiology guidelines. Additionally, we introduced issues related to surgery after cardiac stent placement as illustrated by the case of Ms. X, a 66 year old patient with a suspicious lung lesion that was discovered during hospitalization for a heart attack and subsequent cardiac stent placement. Ms. X’s case highlights some of the concerns faced by patients and their physicians when urgent health conditions emerge in this cardiac population. An excellent article by Dimitrova, Tulman & Bergese further explains aspects of this topic including drug-eluting stents, stent thrombosis and antiplatelet therapy.
A brief review of the literature surrounding this issue showed a dearth of data specifically related to patients undergoing lung surgery after cardiac stent placement. However, a recently published study gives a more detailed look at these patients; including their morbidity and mortality after lung surgery. This information is a critical part of the surgical decision-making process for both the patient and the provider.
The Fernandez study
“Incremental risk of prior coronary arterial stents for pulmonary resection,” is the title of the article in the April 2013 issue of the Annals of Thoracic Surgery. In this article, thoracic surgeon, Dr. Felix Fernandez and his colleagues at Emory University School of Medicine discuss the results of their retrospective cohort study evaluating outcomes in 519 patients after lung resection. All of these patients had nonsmall cell lung cancer (NSCLC) and had received cardiac stents within a year of their lung surgery.
Cardiac stents versus no cardiac history
These patients were compared to 21,892 lung surgery patients in a national database who had no recent cardiac history. Researchers compared the rate of major adverse cardiac events (MACE) in both groups in the first thirty days after their lung surgery. These cardiac events included different types of heart attacks, stent thrombosis, repeat revascularization (did patients need cardiac surgery, angioplasty or another stent after this surgery?) and mortality.
Comparing apples to oranges?
While the study categorized “stent patients” as all patients that received a stent within one year of lung surgery, over half of the stent group (289 patients) had received a stent less than 90 days prior to their surgery. This is important since the timing of surgery and the recommended duration of dual antiplatelet therapy (aspirin and clopidogrel) is dependent on the type of stent placed. According to current recommendations, patients with bare metal stents may discontinue clopidogrel (or clopidogrel equivalent) six weeks after stent placement. However, currently the vast majority of stents placed in the United States are drug-eluting stents (DES) which require a full year of treatment or more. This fact hits at one of the biggest weaknesses in this study, which relies on data collected from 1998 to 2005. Prior to 2004, there was no alternative to bare metal stents, making the trial patient population very different from today’s surgical population and our patient, Ms. X.
Another study dated to 2012 by Voltini, Rapicetta, Luzzi, Paladini et. al examined the outcomes in nonsmall cell lung cancer (NCLC) patients undergoing lung resection who perceived prophylactic coronary angioplasty and stenting as part of their pre-operative cardiac evaluation. In this very small study of 16 patients, all patients received bare metal stents and proceeded to surgery after four weeks of dual antiplatelet therapy. Clopidogrel was discontinued five days prior to surgery and patients were switched to a heparin medication until the time of surgery. The authors reports no intraoperative deaths and no major cardiac complications. However, this contrasts with the majority of published reports showing, on average, a nine percent risk of peri-operative heart attack and a mortality of three percent.
Using intravenous medications during surgery to decrease cardiac risks
In the review of the literature, several authors discussed the addition of short-acting blood thinners like bivalirudin Angiomax) or heparin infusions during surgery to reduce the risk of an acute event such as stent thrombosis but there have been no definitive studies to determine the effectiveness or safety of this proposed treatment.
How does this impact pre-operative evaluation decisions?
This information isn’t limited to patients like Ms. X. It also hits at the heart of the pre-operative evaluation as illustrated by our next case composites: Mr. D & Ms. C
Mr. D is a 55 year old obese Hispanic male with a history of diabetes (since 2004), hypertension, high cholesterol with a sedentary lifestyle as a financial planner for a large corporation. He has a strong family history of cardiac disease, both of his brothers (aged 43, and 47) have had bypass surgery, and his father died at the age of 52 of a heart attack. He reports minimal physical activity with the exception of frequent games of catch with his two young grandsons. At a recent insurance required physical examination, Mr. D underwent a routine chest x-ray which showed a 1.5 cm nodule on the upper lobe of his left lung. On PET/ CT scan, the nodule is suspicious for malignancy with an elevated SUV of 11, but there are no signs of metastasis or spread. He is scheduled to undergo a VATS (video assisted thoracoscopic surgery) with wedge biopsy, and probable lobectomy but as part of his preoperative work-up he is referred for cardiac evaluation. While he was asymptomatic, due to his multiple risk factors and family history, the cardiologist performed a treadmill stress test. During the test, the patient was only able to walk for 3 minutes due to discomfort in his knees and demonstrated a hypertensive response (BP 220/100 along with changes in several cardiac leads.) The cardiologist would now like to schedule a cardiac catheterization for Mr. D prior to his lung surgery.
What is the best treatment for Mr. D in the scenario above? How will treatment for cardiac disease alter or change surgery for his lung nodule?
In Mr. D’s case, after a discussion with the thoracic surgeon, the cardiologist performs a cardiac catheterization which shows moderate diffuse disease as well as a high grade lesion in the right coronary artery. Due to the presence of the high grade (95% blockage) in the right coronary, the cardiologist places a bare metal stent in the right coronary artery and starts Mr. D on aspirin and clopidogrel, in addition to a beta blocker and statin medication. He also counsels Mr. D and his family on risk factor reduction, including tight glucose control, and use of an ace-inhibitor due to his diabetes. Surgery is delayed for four weeks.
Prior to surgery, Mr. D returns to the surgery office to discuss his options, which include surgery or chemotherapy and radiation. After all of his risks are explained to him, including an elevated risk of heart attack or death, Mr. D and his family elect to proceed with surgery since it is the best chance for curative treatment. Mr. D has done well with his new medication regimen and reports good glucose control after meeting with a diabetes educator in his doctor’s office. He is nervous but anxious to proceed with surgery. Clopidogrel is discontinued a few days prior to surgery, and Mr. D is giving another shorter acting medication called enoxaparin, and his aspirin is continued. As recommended by Dimitrova, et al. his surgeon coordinates his surgery to ensure that his cardiologist will be available for urgent reintervention, if necessary.
Mr. D undergoes a single port thoracoscopic wedge biopsy under close anesthesia monitoring. Intraoperative pathology indicates that the lesion is indeed cancer, so the surgeon proceeds with a lobectomy with extensive lymph node dissection. Surgery is uncomplicated, and post-operatively, Mr. D is restarted on his clopidogrel. Mr. D recuperates well and is discharged 3 days after surgery.
Does everyone need a cardiac evaluation before surgery?
Ms. C is a 44 year old African American schoolteacher, and the mother of three teenaged children. She is a nonsmoker, nondrinker and marathon runner. Her past medical history is significant for a caesarean section with her last child and a drug sensitivity for morphine. Last week, while running one dark early morning in her neighborhood, she is startled by a large dog and trips, falling several feet into a small culvert next to the road. She summons an ambulance using her cellphone complaining of chest wall pain, and ankle instability. Paramedics on the scene note extensive cuts and abrasions from her fall and suspect possible ankle and rib fractures. In the emergency room, the orthopedic surgeon rules out an ankle fracture. A chest x-ray rules out rib fractures but a large mass is noted in the right upper lobe.
What is the next step for Ms. C? Does she need to see a cardiologist?
Ms. C is a young, otherwise healthy female with an incidental finding of a suspicious mass. Given the absence of risk factors, current cardiology recommendations suggest that she does not need further cardiac evaluation. Several large research studies suggest that the risk of a major cardiac event during thoracic surgery in this patient is around 0.36%.
For Ms. C, the most important pre-operative evaluation will be further imaging studies such as CT scan to determine whether surgeons can resect the large sized mass.
No clear cut answers
While the population of patients treated with coronary stents continues to grow, there is little agreement among specialists as to the timing, and precautions necessary for patients who cannot postpone surgery for other conditions, such as lung cancer. The popularity of drug-eluding stents due to their increased durability; has complicated the issue because of mandatory clopidogrel use, which increases the risk of bleeding during surgery.
As researchers continue to investigate the safety of surgery after cardiac stents, patients need to be vigilant in discussing these concerns with physicians. Non-elective surgeries such as surgery for lung cancer will need to be carefully timed and coordinated with input from both the thoracic surgeon and the cardiologist. Peri-operative risk assessment should weigh the benefits and risks of delaying surgery versus continuing anti-platelet agents during the operative period. This may include intravenous agents at the time of surgery, as well as preparing for possible emergency cardiac interventions, should problems develop.
Communication is key
Despite the lack of definitive answers, it remains clear that patients and providers need to have in-depth and frank discussions of the risks, benefits and alternate options prior to proceeding to the operating room.