Somewhere in the west of the Netherlands, on a Thursday morning roughly five years ago, all hell broke loose. Mark, in his late twenties, involuntarily jumped up an inch or two from his mattress. He fell down, only for it to happen again. And again. At each brief but intense spasm all muscles in his upper body contracted, after which he collapsed back into his pillows. ‘I tasted blood, I couldn’t get up. I woke the whole house with my screaming. It feels as if a bomb goes off in your chest.’

As a cardiac patient, Mark knows the sensation of receiving a shock from his ICD, a tiny device in his chest that maintains his heart rhythm. The device administers electric shocks when the heart slides into an unhealthy rhythm, functioning as a cardiological reset button. ‘When it saves your life, it’s a godsend.’ But that morning it wasn’t his heart that spiralled out of control - it was the device itself.

Mark doesn’t want to feature in this article under his real name, as he fears it might deteriorate the relationship with the doctors who treat him. ‘My mother was petrified, and my younger sister stood in the bedroom doorway in shock. They rang the ambulance, but because the device kept going off again and again, I couldn’t be placed on a stretcher. In the end I managed to get downstairs on my own, I can’t remember how.’

The paramedics knew they could shut down such a device by putting a magnet on the patient’s chest, but they were unsure which magnet exactly they needed in Mark’s case. As they frantically searched, Mark’s younger sister came in, holding a toy magnet. ‘She wanted to help, to stop the shocks.’

On the other side of the globe, Lyn Farley, an oyster farmer in Australia, received 60 shocks out of the blue. Now, eleven years later, she can still sense the device’s shocks in her chest, even though it’s long been removed. ‘Phantom shocks’, her doctor calls it.

A few miles outside of Berlin, in March of 2017, a 76-year old woman suffered from erroneous shocks for four hours in the middle of the night. Her device went off no less than 105 times. All the while she was unable to shout for help, as a stroke had left her with difficulties in speaking. The shocks went on and on. They only stopped when the device’s battery died.

In each of these cases, the doctors involved arrived at the same conclusion: the issue lies with the wiring that connects the device to the heart, called the ‘lead’. In all of the above cases, these are branded the same. Every single one of them is a ‘Linox lead’, sold by manufacturer Biotronik.

For over a decade already, scientific publications the world over have been highlighting issues with Biotrionik’s leads. Cardiac patients with these leads - compared to those by other manufacturers - run a higher risk of what medical professionals call ‘inappropriate’ shocks. These shocks can be dangerous, and in rare cases cause cardiac arrhythmia. Despite ample scientific evidence, authorities responsible for monitoring such medical risks, including the Dutch Health and Youth Care Inspectorate, have never intervened.

The Dutch weekly magazine De Groene Amsterdammer, online platform Investico, medical journal Het Nederlands Tijdschrift voor Geneeskunde and tv-show Nieuwsuur have, for the first time, tallied all the available scientific literature on the ICD lead manufactured and sold by Biotronik. We spoke to doctors, the inspectorate, and the company itself. Behind the scenes Biotronik and cardiologists have been arguing for years about the faulty leads. Even though scientific evidence is mounting against the company, they nonetheless persist that their product works as it should, systematically denying any claims to the contrary.
In 2019, Biotronik halted the sale of Linox leads world-wide. By then, they’d already sold 250.000 of them. At least a thousand Dutch cardiac patients still carry the lead in their chests, connected to their heart. The Dutch Association of Cardiologists (NVVC) has not informed them about the well-documented issues with Linox leads.
In the last ten years the FDA, the US agency tasked with monitoring the medical industry, received almost a thousand complaints about Linox-related inappropriate shocks. Since 2009, the Dutch health inspectorate has received 401 reports of “serious incidents” related to Linox, 59 of which involved unintended shocks. After each of these incidents, the manufacturer provided such ‘clarification’ that the inspectorate concluded ‘there were no grounds to assume that the leads do not work properly.’

That response is severely problematic according to experts: recent, large-scale research shows that ten percent of the leads malfunction. ‘The inspectorate has to do something’, says emeritus professor patient safety Jan Klein. ‘But each of the involved parties is cowering behind the other.’

Alexander Maass had only been working as a cardiologist at the University Medical Center Groningen for a few years, when in 2010 several of his patients noticed a recurring problem. Seemingly at random, their ICD devices administer shocks of 800 volts, more than three times the voltage of a regular Dutch power plug. Maass studied each of their files, looking for an explanation. All patients that rely on such a device can run into issues with inappropriate shocks, for example if its settings are configured incorrectly. But when he did a read out of the ICDs, he noticed something odd. The electrograms showed a large number of inexplicable signals, something cardiologists call ‘noise’.

The ICD’s weakest point, Maass knew, is the wiring that connects the device to the heart. It could break, transmitting the ‘wrong’ signal, which would explain the noise he saw. This might lead the device to misregister heart activity - mistakenly thinking it’s beating at a dangerous pace - and administer a shock even though the heart is functioning properly. Maass also noticed another pattern: each case concerns Linox leads.

This type of lead is first launched in 2006. At the time, Biotronik is caught in a heated race with its competitors: the goal is to produce ICD leads that are as thin as possible. The thinner the wiring, the easier it is to connect them to the heart. Shortly after introducing ‘the Linox’, two of Biotronik’s competitors take their products off the market, as they malfunction frequently and are even linked to multiple deaths. It marks a turning point for Biotronik’s sales. ‘From then on, Dutch cardiologists started implanting thousands of Linox leads’, Maass says.

But gradually, the thin wiring also begins to cause problems. In most cases, cardiologists are able to intervene when they notice that the ‘noise’ on the electrogram increases. At times, however, there aren’t any such signs to serve as a warning. The devices simply start administering shocks, entirely out of control. ‘I asked around among other cardiologists and they told me they’d seen similar issues’, Maass says. ‘That’s when I knew: something is seriously wrong.’
Under European regulation, the manufacturer is responsible for detecting any problems with their products. Biotronik is obliged to collect data on this and take action if the company deems it necessary. So Maass, just as his colleagues at other Dutch hospitals, dutifully reported his findings to the manufacturer. ‘In response, Biotronik simply told me nothing was wrong.’

If the company were to acknowledge the problems with their own product, it could lead to serious legal claims from patients - not to mention reputational damage. In 2019, Maass, the cardiologist from Groningen, received an invitation to the Biotronik headquarters in Berlin. Three staff members welcomed him. One of them was the director of patient safety, who assured him everything is alright. ‘They admitted the lead does not perform as they’d hoped, but told me that the problems weren’t severe enough to issue an official safety warning.’

Doctors across the world arrived at the same conclusion as Maass. The St. Paul’s Hospital in Vancouver, for example, ran a study into roughly five hundred patients who received Linox leads. ‘A few of them suffered from inappropriate shocks due to faulty leads, says Gareth Padfield, who was a cardiologist there at the time. Padfield and his colleagues monitored all patients closely and discovered a ‘high rate of Linox lead failure’, according to the paper they published in a scientific journal in 2014. Now, looking back, Padfield says: ‘Our message was clear. These leads are worse than those of other brands on the market.’

More and more studies were published on issues with Linox, from Spain and Switzerland to Japan and New-Zealand. In total, we tally ten studies where doctors share the same findings: Linox leads malfunction remarkably quickly and have a higher risk of causing inappropriate shocks. Cardiologists who show their findings to Biotronik receive one and the same response. ‘They simply didn’t acknowledge the problems’, says Jamil Bashir, who worked with Padfield on the Canadian study. ‘They told me that it wasn’t a case of a manufacturing error, as the leads seemed to malfunction in different places each time’, says Rik Willems, a Belgian cardiologist. ‘They said they hadn’t heard of similar cases in other hospitals’, the Spanish cardiologist Diego Perez.

In Australia, Bradley Wilsmore presented his findings at a conference. He was the cardiologist who treated Lyn Farley, the oyster farmer who suffered 60 inappropriate shocks and still senses ‘phantom shocks’. Dr. Wilsmore: ‘Afterwards, all kind of doctors came and spoke to me about their issues with Linox. Some time later, the boss of Biotronik Australia came to my office on a surprise visit. In a thirty-minute presentation, he explained just how good the lead was.’

The company refers to its own study, which monitored almost 4000 US patients who received Linox leads. It was by far the largest study conducted at the time, with its 2016 publication being accompanied by a Biotronik press release. ‘These results should provide assurance to doctors and their patients that Linox leads are safe and reliable’, said the study’s principal researcher - who was paid by Biotronik. ‘The scale and thoroughness of our study demonstrates Biotronik’s deep commitment to evaluating our products’, the company’s vice president Manuel Ortega added. ‘Good is never enough for us.’

But the results are less convincing than the manufacturer makes it seem. The study ran for a short time span: patients were monitored for no more than five years. But, as other academic findings have since shown, the Linox leads tend to malfunction after the first five years.

Another cardiologist - who prefers to remain anonymous to protect his working relationship with Biotronik - authored such a study, which indicated significantly higher failure rates than the company reported. Before publication, he shared his findings with them. ‘They simply didn’t believe our data’, he says. ‘They even threatened to cut the funding for our educational programme if we’d publish anything negative about them.’ Nonetheless, he decided to proceed, ‘because we do not like it when companies threaten us.’

This pattern of complete denial also appears in an analysis of all cases reported to the US Food and Drug Administration in the past ten years. We found 934 reports stemming from Biotronik and hospitals about inappropriate shocks due to faulty Linox leads. The company denies responsibility in every case. Each complaint features the same argument phrased in identical language. The wear on the leads is not due to the wiring itself, but due to ‘lead movement’ or ‘interaction with atypical tissues’, Biotronik states time and again. ‘There are no indications of a material defect or a manufacturing error.’

The cardiologists we speak to all emphasise that, with time, any lead can malfunction. Even though they observe the Linox leads to fail disproportionately often at their own hospital, they do not know whether this is also the case elsewhere. There is no central European registry for problems and complaints related to medical devices. There’s only one party with access to such an overview for Linox, the cardiologists say. It’s Biotronik. They register all global complaints, and therefore everyone - worldwide - looks to them for guidance.

Behind the scenes at Biotronik, the company does respond to the problem. ‘Time and again I saw issues with Linox’, says Brian, who prefers a pseudonym to protect his identity. He worked at Biotronik for years and sold their products to hospitals. More and more doctors came to him and expressed their worries. ‘I asked my superiors how to deal with it - but they replied very defensively.’

After the Canadian study appeared, Brian and his colleagues received a six-page print-out on ‘how to respond to customers’ questions and worries’. The document listed the contact details of the Head of Marketing at the Berlin headquarters. The guidance - seen by this editorial team - consists of ten so-called ‘key arguments’. Biotronik staff is to consistently refer to the company’s own study, which shows the product works as it should. They’re also advised to ‘not proactively engage in a debate about the long term performance of Linox leads.’ ‘Talking points’, says Brian. ‘Things like: if a doctor says this, you should say that. Just like politicians do.’

Even though Biotronik publicly insists on the efficacy of Linox leads, the manufacturer repeatedly changed the product’s design. In 2010, for example, a new, smooth silicon film was added to the lead, intended to reduce friction.
Another former Biotronik employee says that these alterations confirmed his suspicions. ‘From that moment, I knew something was wrong with the lead’, he says. ‘Why would you sell a new version if the old one supposedly still works just fine?’ The cardiologist from Groningen, Maass, noticed the same thing. ‘There have been three generations of redesigns’, he says. ‘All of them have been changed exactly at the location where we said the malfunctions originated. This gives me the impression that Biotronik did know where the weak spots were.’

In 2019 Biotronik stopped selling the Linox leads. But with the disappearance of the leads from the market, the need to address the problem also faded away.
Doctors simply switched to another type of lead, with Linox gradually disappearing from the examination room, and with it, from sight. Most of the medical professionals seemingly would rather forget the whole affair and refer to it as ‘an old problem’, unwilling to field any questions about it. Above all, cardiologists have no interest in dealing with the fuss - they’d rather avoid phone calls from worried patients and a subsequent conflict with a manufacturer with whom they have ‘a good working relationship.’

April 4th, 2025. In a quaint, 15th-century chapel in central Amsterdam, cardiologist Erik Oosterwerff of the University of Amsterdam takes to the stage for the defense of his dissertation. His work is the largest study ever conducted into Linox leads, at the initiative of the Dutch Association for Cardiologists (NVVC). The dissertation publication was not accompanied by any press release or publicity campaign, and Oosterwerff declined to speak to us on-record.

Despite the limited attention it received, the study’s results are of serious medical importance. Finally, Linox related issues have been proven at a large scale. No less than ten percent of Dutch patients suffer from a faulty lead after six years, Oosterwerff found. It’s more than three times what cardiologists see as the acceptable threshold for lead failure. Eighty-five Dutch patients suffered inappropriate shocks. ‘It’s remarkable that Biotronik never issued a recall’, Oosterwerff writes in the dissertation.

The absence of such intervention by the manufacturer has far-reaching consequences. If the company decides to take action, it issues an official safety warning related to the product. A special commission of the Dutch Association of Cardiologists would then immediately draft a plan on how to deal with affected patients, whom they would notify. However, as long as the manufacturer refuses to issue such a safety warning, patients are kept in the dark. ‘We decided not to notify patients’, says Michiel Rienstra, vice president of the association. ‘We want cardiac patients to continue to trust their device.’

The association states they are under no obligation to inform patients, because ‘already in 2014, we notified all ICD-cardiologists in the Netherlands’ about issues with Linox leads. They claim to have advised doctors at the time to monitor affected patients more closely. They could do this via ‘at home monitoring’, where a device automatically scans the ICD’s activity and shares this with the hospital. This would allow for the early detection of any issues. The association admits there is no way for them to know whether doctors actually do this. ‘I have not received any information on that’, Rienstra says.

Three out of the twelve Dutch medical cardiac centres who still have patients with Linox leads refuse to answer Investico’s questions on whether they monitor their patients at home. The remaining nine organisations say they do. Two out of twelve stated that they had never experienced issues with Linox leads, but that they had not been informed about the risks by the Association of Cardiologists either. ‘We never received any negative information about these leads’, the Franciscus Hospital in Rotterdam states.

The cardiologists association refers us to the Dutch Inspectorate for Health and Youth Care, the oversight body tasked with monitoring hospitals and the manufacturers of medical devices. ‘The inspectorate has never informed us that there’s an issue with this lead’, says Rienstra, the association’s vice president.

Remarkably, the inspectorate refers to the cardiologists, saying they’ve not received any reports about Linox leads ‘in the past decade’. A spokesperson adds: ‘The association also did not share the results of Oosterwerff’s dissertation with us.’

After we present our findings to the inspectorate, they contact Biotronik. In turn, the inspectorate refers us to the study which Biotronik itself commissioned, with the short follow-up time, and another one which is supposed to support the claim that the Linox leads do not present a medical risk. We contacted the principal author of the latter study to ask whether the publication does indeed show Linox leads are safe. He tells us that his study has severe limitations and by no means can serve to support the inspectorate’s claim.

Upon request, the inspectorate shared all reports of Linox malfunction it received since 2009. These amounted to 401 reports of ‘serious incidents’, a category which comprises either premature death or ‘severe deterioration of overall health’. Despite this, the inspectorate saw no reason for worry or intervention. A spokesperson says this number is not higher for Linox than for other types of leads. That in itself is remarkable because, after follow-up questions, they admit they have no information on how many Dutch patients received Linox leads in total. This means the oversight body only has absolute numbers, not relative ones, which makes it impossible to judge whether or not 401 serious incidents is a high rate.

Regardless, the inspectorate says that ‘for now, there are insufficient grounds to assume that the leads work less well than other, comparable leads.’

It underlines the central problem: because when would ‘sufficient grounds’ be achieved for the inspectorate to intervene? This is where the oversight of medical device implants is critically flawed. Doctors do not have to take action as long as the inspectorate doesn’t sound the alarm, which they don’t have to do because they receive - or collect - too little information to conclude whether there is indeed a serious problem.

The only party that possesses both the necessary information and the legal obligation to intervene when issues arise, is the manufacturer. It’s also the only party with a commercial interest in keeping such information a secret.

There has been a string of serious failures in the industry due to exactly this balance of power and information. Take, for example, Philips’ machines against sleep apnea. For years, patients ran the risk of inhaling potentially carcinogenic gases. ‘Time and again, manufacturers’ inspection of their own products seems to fall short’, says Jan Klein, emeritus professor of patient safety. ‘Companies simply refuse to look at any issues, also because they quite frankly stand to benefit from keeping any attention away from it.’
Recent changes to European legislation have left manufacturers’ information monopoly and their unenforced duty of ‘self-regulation’ intact. In practice, doctors and regulators keep waiting for companies to sound the alarm when a product fails.

But even within this system, health care workers can take responsibility and inform their patients, says professor Klein. ‘Doctors, as well as the Association for Cardiologists, don’t have to wait until the manufacturer responds to an issue.’ Corrette Ploem, professor in health care law, agrees: ‘The inspectorate does not step up to the plate and seems to only perform some general checks. That way, it’s impossible to say with such certainty that there isn’t a problem.’
‘If I were the inspectorate and I’d received reports about problems like this, I would have taken action’, says Martin Schalij, doctor and board member at the Leiden University Medical Center. ‘I wouldn’t say: all of this seems fine to us.’

By the time Mark got to hospital, he’d bitten through his own cheeks. Miraculously, the dozens of intense shocks have left no permanent damage to his heart. He is, however, left with PTSD-related symptoms: anxiety, panic attacks and nightmares. ‘I underwent two years of intensive therapy to process all of this. I also took anti-anxiety medication, which I only barely managed to quit’, he says.

The Association of Cardiologists say that they informed all ICD-specialists in the country about Linox leads at the time of Mark’s ICD malfunction. They say they’d also already drafted medical advice, urging doctors to apply at home monitoring for such patients. ‘But I didn’t get that until after I went through all those shocks, even though they of course knew I had Linox leads.’

‘No one ever told me these wires have a great risk of malfunction’, Mark adds. ‘I’m mortified this might happen again. Your entire well-being depends on just one tiny wire. It’s the thread I hang by.’

Biotronik’s response
According to Biotronik ‘there is no indication for issuing a Field Safety Notice’’. The study they commissioned only monitored patients for 5 years because ‘this was defined by regulatory requirements set by the FDA’. The alterations in the Linox design are ‘a normal and essential part of medical innovation.’ The company acknowledges that they sent standard responses to medical oversight bodies, but they underline that ‘each report is based on a case-specific investigation.’ They also confirm they circulated communication manuals among their staff after publication of the Canadian study into Linox leads, ‘to avoid initiating discussions about a single publication with questionable methodology.’

In 2014 and 2022, Biotronik settled with the US Department of Justice over allegations of bribing doctors. The company was alleged to have paid cardiologists to use their products. In total, Biotronik paid just under 18 million dollars.

Since 2020, the fiscal investigations unit of the national tax agency in the Netherlands is investigating four payments made by Biotronik, the company mentioned in its 2022 financial report. Dutch newspaper NRC reported that this is related to a case of alleged corruption at the Isala Hospital in the city of Zwolle.

Do you wish to get in touch with the authors of this investigation? Reach out at veen@platform-investico.nl or dequeker@platform-investico.nl