Patients who have had valve implants or prosthetic product implants are at higher risk of infection with a bacterial species of nontuberculous mycobacterium (NTM), according to the Centers for Disease Control and Prevention. Based on the number of surgeries conducted over the past four years, an estimated 600,000 patients are at risk for a potential infection.
The CDC has confirmed infections in 28 heart surgery patients in the US. Meanwhile, worldwide, at least 12 patient deaths have been reported, according to the Food and Drug Administration.
Though upsetting, this news should not raise pulses, says Dr. Vinod Thourani, co-chair of the American College of Cardiology’s surgeon’s council. “The overall risk is exceedingly low,” said Thourani, who is also a professor and chief of cardiothoracic surgery at Emory University Hospital.
The CDC estimates that in hospitals where at least one infection has been identified, the risk of a patient getting an infection from the bacteria is between about one in 100 and one in 1,000.
The source of a potential infection is the Stöckert 3T heater-cooler device, produced by LivaNova PLC. Heater-cooler devices are commonly used during cardiac surgical procedures to warm and cool a patient’s blood and organs. During manufacture, these devices may have become contaminated with NTM.
Infections reported worldwide
Symptoms of infection with NTM include night sweats, muscle aches, joint pain, weight loss, fatigue and unexplained fever. The pulmonary illness can take more than a year of antibiotic treatment to cure.
Between January 2010 and August 2016, the FDA received 91 reports of patient infections worldwide associated with the 3T heater-cooler unit, noted Kotz, and of these 91 reports, at least 79 infections were confirmed.
Following exposure to NTM through open-heart surgery, symptoms often take months to develop and so a diagnosis can be missed or delayed — sometimes for years — making these infections more difficult to treat. No test can determine whether a person has been exposed to the bacteria, though a laboratory culture can diagnose an infection. The slow growing nature of the bacteria can require up to two months to rule out infection, according to the CDC.
“What people should know is transmission can occur from environmental sources at any time, it is not specific to heart surgery,” said Thourani, who also said NTM doesn’t spread from infected people to uninfected people — it’s not contagious.
It is also unlikely a healthy patient coming in for elective heart surgery would develop an infection, noted Thourani.
More than 250,000 heart bypass procedures are performed every year in the US and of these operations, 60% use the heater-cooler device associated with these infections, the CDC said.
The CDC and the Food and Drug Administration initially published alerts about these heater-cooler devices in 2015 after investigators in Switzerland reported a cluster of six heart surgery patients with an invasive infection of NTM. Shortly after this, a Pennsylvania hospital also identified a cluster of invasive NTM infections among patients who had undergone open-heart surgery. Cases have also been confirmed in Iowa and Michigan.
This week the federal agencies updated their safety communications based recent reports of infections in patients who had undergone cardiothoracic surgeries using the 3T heater-cooler units. Results of genome sequencing strongly suggest the 3T units are the source of contamination, the CDC said.
Class action lawsuits
In February 2016, a class action complaint — naming the FDA’s Warning Letter as evidence — was filed against LivaNova in Pennsylvania, the company stated in a recent quarterly report filed with the Securities Exchange Commission. Patients in the suit underwent open heart surgeries at WellSpan York Hospital and Penn State Milton S. Hershey Medical Center in 2015. Since then, LivaNova has been served with additional similar lawsuits tied procedures performed at these same two hospitals as well as Greenville Health System Hospital in Greenville, SC. However, the cases in Greenville are not conclusively linked to the device and are not counted in the number of cases identified by the CDC.
“We intend to vigorously defend each of these claims,” stated the company in its quarterly statement.
Pennsylvania’s Department of Health has confirmed 21 cases of infections related to the machines so far, said April Hutcheson a spokeswoman for the department.
Patients who have had open heart surgery since 2012 should be aware of the signs of potential infection in case they’ve been unknowingly exposed to NTM and keep in touch with their doctors for further evaluation, the CDC advised. The federal agency also recommended hospitals immediately assess their heater-cooler units. Because heater-cooler devices can be extremely difficult to disinfect once contaminated with NTM, the CDC recommends hospitals continue using the device only if following the manufacturer’s latest recommendations for sterilization in between patients and proper use.
The CDC also recommends hospitals consider surveillance of patients who have undergone open-chest cardiac surgery involving the 3T heater-cooler device.
“This is something we are taking very seriously but we are not alarmed about this,” said Thourani, who added that heart surgery may be life-saving: “We have not recommended ceasing cardiac surgery based on what we’ve heard in the last 48 hours.”