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Contaminated HCDs cause up to 282 cases of M. chimaera per year
Globally, contaminated heater-cooler devices used during cardiac surgery may cause up to 282 cases of invasive Mycobacterium chimaera infection each year, including as many as 80 cases in the United States, researchers said.
Heater-cooler devices (HCDs) are used with heart-lung machines to regulate body temperature during cardiothoracic surgeries and other procedures, including more than 250,000 heart bypass procedures in the U.S. each year, according to the CDC. The leading HCD brand, LivaNova 3T, has been implicated in a global outbreak of difficult-to-diagnose M. chimaera infections, likely a result of the machines being contaminated at the German plant where they are manufactured. More than a third of the devices may be contaminated, researchers have said.
Last year, experts advised hospitals on how to locate and notify patients who may have been exposed to slow-growing M. chimaera via the machines and how to separate their LivaNova 3Ts from the operative field, where patients can become infected through bioaerosols produced by HCDs during surgery. The experts said any patient who has been exposed to one of the devices since 2006 should have M. chimaera in their differential diagnosis.
There have been around 120 cases reported globally as of September 2017, according to Rami Sommerstein, MD, internal medicine and infectious diseases specialist at Bern University Hospital in Switzerland, and colleagues.
“The disease appears to be rare and most commonly affects patients after valve replacement or other implant procedures in open heart surgery,” Sommerstein and colleagues wrote in Emerging Infectious Diseases. “Currently, the extent of the epidemic is unknown. We aimed to estimate the global epidemiology of disseminated M. chimaera disease associated with open heart surgery.”
Sommerstein and colleagues reviewed Swiss data from to find patients who were diagnosed with M. chimaera infections caused by the outbreak strain after having open heart surgery, including implant surgery. Using the data, they estimated that incidence of proven cases per 1 million inhabitants increased from 0.16 (95% CI, 0 to 0.37) in 2011 to 0.25 (95% CI, 0.05 to 0.45) in 2016, and the prevalence of infections per 1,000 valve replacement surgeries increased from 0.52 (95% CI, 0 to 1.41) in 2008 to 0.94 (95% CI, 0.05 to 1.83) in 2014.
“Considering an estimated 300,000 global annual valve replacement surgeries in the 10 major market countries and a U.S. population of 323 million, we can extrapolate our findings to an annual incidence of 156 to 282 cases for the 10 major valve replacement markets and 51 to 80 cases in the United States alone,” Sommerstein and colleagues wrote.
They said their estimate is much higher than the reported cases of M. chimaera disease related to valve replacement, but this may be due to underreporting or underdiagnosing.
“Our data provide an estimate of the global burden of M. chimaera associated with open heart surgery, enabling policy makers to guide actions and to decrease the risk for transmission from HCDs,” they concluded. “Our data suggest implementation of systematic lookback approaches in each country where LivaNova 3T HCDs have been used to optimize case finding. In addition, countries may consider mandatory reporting of invasive nontuberculous mycobacterial infections.” – by Gerard Gallagher
Disclosures: The authors report no relevant financial disclosures.