Aug 6, 2021 This Week in Cardiology Podcast

John M. Mandrola, MD


August 06, 2021

Please note that the text below is not a full transcript and has not been copyedited. For more insight and commentary on these stories, subscribe to the This Week in Cardiology podcast.

In This Week’s Podcast

For the week ending August 6, 2021, John Mandrola, MD comments on the following news and features stories.

The Latest COVID-19 Surge

The Delta variant spike is in full swing, not just in the United States but in other countries as well. Our ICU went from a one to two COVID-19 patient average in early July to 12 now. Boom. This spike occurred in only a week. My hospital is in a medium-size city, but our system runs hospitals in rural counties, and they have even more pressure due to a smaller number of ICU beds and higher percentage of unvaccinated adults with risk factors. States and cities with higher vaccination rates are faring better. I had a chat with our ICU doc on the COVID service. He told me that in our ICU, it is 100% unvaccinated and 100% patients with risk factors, primarily obesity. He also said that while he has seen some vaccinated patients get hospitalized, none get sick enough to make it to the ICU for pneumonia. He also noted the change in age range: now it is younger patients, ages 30 to 60, in the ICU.

The logical conclusion is that the higher vaccination rates in older adults have changed the demographics of ICU COVID-19. This is exactly what the original trials showed. The vaccines protect against severe disease. It transforms SARS-CoV-2 into a far less virulent virus.

You hardly need a cardiologist to tell you the solutions: increase the rate of vaccination among adults—especially those at risk. Then, if we are ever going to have a normal society again, we must figure out how to exist with endemic SARS-CoV-2.

My speculation is that the rapid rise of cases, surely related to the increased transmissibility of the Delta variant, and the global situation where most of the world’s population remains unvaccinated, and now the evidence that there are clearly animal hosts for SARS-CoV-2—even deer have SARS-CoV-2—means that no matter how hard we try, everyone will eventually be exposed to SARS-CoV-2.

I read from a Hilda Bastian Tweet that even in Australia, with their strict tracing and quarantine measures, “mystery cases” of SARS-CoV-2 have been noted. And if I am right about not being able to evade exposure to this virus, this means there will be a binary choice: be vaccinated or take your chances, because avoidance won’t be an option.


Speaking of medical evidence, it boggles my mind that many of my colleagues are openly saying they have had, or plan to have, booster vaccinations based on a preprint that measured declining vaccine efficacy (VE). Here are the reasons this is nuts:

  • There is no data on the efficacy of boosters.
    VE against severe disease in that preprint remained at 97%.

  • You don’t know if a booster is necessary or safe. I bet it is safe, but you don’t know without outcome evidence. Myocarditis-like signals are not easy to detect.

  • It is terribly selfish and unbecoming. Huge swaths of humanity can’t get any access, and rich, mostly low-risk doctors, are bragging about getting extra shots. Such behavior shreds public trust.

  • Boosters don’t slow the development of variants. In fact, it may increase the spread of variants. The virus can spread and mutate in the large groups of humanity that don’t have access to vaccines. A variant that forms on another continent will easily travel across the globe.

The one caveat on boosters: You can make an argument that it most fits for the immune-compromised, but again, this, too, should be studied systematically.

COVID Vaccine Myocarditis and Pericarditis

This week, JAMA published a research letter on myocarditis and pericarditis post vaccine. It’s both good news and bad news. First author George Diaz and others from the Providence Healthcare system reported on clinical records of 2 million adults who received COVID vaccines.

  • The incidence of myocarditis was 10 per million.

  • It occurred 3.5 days out from the vaccination.

  • 15 of 20 cases were male.

  • Most cases occurred after the second shot.

  • 19 of 20 were admitted to hospital; median age 36.

  • All were discharged; no deaths.

  • The incidence of pericarditis was 18 per million.

  • It occurred a median of 20 days out.

  • 27 of the 37 were male.

  • Slightly more of the cases occurred after the second shot.

  • Median age was a bit older at 59.

  • 13 of 37 were admitted and all were discharged.

You might wonder what the rates of myo- and pericarditis were before vaccines: For myocarditis, it was 16.9 per month pre-vaccine and 27 per month during the vaccine period; P < 0.001. The same relationship was seen with pericarditis, with significantly more during the vaccine period.

The CDC recently reported an association between COVID-19 mRNA vaccines and myocarditis, primarily in younger male individuals within a few days after the second vaccination, at an incidence of about 4.8 cases per 1 million. The authors of the JAMA study write: “This study shows a similar pattern, although at higher incidence, suggesting vaccine adverse event underreporting. Additionally, pericarditis may be more common than myocarditis among older patients.”

  • The bad news is that the mRNA vaccines can cause cardiac injury due to inflammation.

  • The good news is that it appears to be at a very low incidence and in these cases the condition resolves without serious complications.

If I were a public health leader, I would state clearly that these are real findings; the vaccines can cause cardiac injury, it is rare, and for adults, especially those with risk factors, such as obesity, the benefits of vaccination far outweigh its risks. I stand by my column on younger adults and adolescents, though. Here the risk of SARS-CoV-2 is far less and different people will feel differently about the harm-benefit calculus.

Heart Rhythm News

The Heart Rhythm Society (HRS) actually pulled off a partially in-person meeting in Boston. I wrote a column about it. Despite 16 late-breaking sessions and 1000 or more original abstracts, I found no practice-changing science.

The two hottest areas of electrophysiology are light on evidence. You all should know about a potential new energy source for ablation in the atrium—pulsed field ablation (PFA). It works via electroporation, a technique that involves applying electrical current to the heart, which then disrupts current flow across the cardiac cell membrane. This results in pore formation and cell death.

The main upside of PFA is its cardioselectivity; it does not harm the adjacent phrenic nerve or esophagus. It's also fast. Rapid electrical isolation of pulmonary veins means patients require less anesthesia. It is quite exciting to see the images of ablation occurring in left atrium (LA) and no damage to nerves and the esophagus.

I see two main areas of concern with PFA.

  • The first is safety: Intracardiac echocardiography reveals huge amounts of microbubbles that occur with PFA. This raises the concern over cerebral micro emboli. Right now there is a dearth of brain MRI data. In my column, I mention an abstract from Andrea Natale himself in which transcranial Doppler in six patients who had PFA revealed concerning signals of micro-emboli.

  • The other issue with PFA is efficacy: I worry that the speed and cardiac selectivity of PFA will induce docs to ablate more LA tissue outside the pulmonary veins. This may or may not be wise. We need outcome and safety data on this new technology.

Another topic of enthusiasm is pacing the area of the left bundle branch (LBB). You may wonder, wait, how do you get a pacing lead near the LBB, that is the left ventricle (LV)? Or, why would you want to? What about His-bundle pacing? Well, my friends, despite its sheer beauty, His-bundle pacing has downsides: it’s hard, sensing can be low, thresholds high, and that means pacer generators may not last as long. LBB area pacing is not quite as hard and gets better sensing and pacing numbers. You do it by moving south on the septum a bit and then screwing the lead through the septum to the other side where the fascicles of the LBB reside. This allows capture of the LBB. You want this because activating the LBB or the left side of the septum preserves left greater than right septal activation and avoids delaying contraction of the LV.

LV delay is the problem with LBB and right ventricle (RV) pacing. Delayed LV activation is the entire reason for biventricular or cardiac resynchronization therapy (CRT) pacing. But here’s the problem with LBB pacing—it requires learning a new technique, we don’t have long-term data on pacing lead performance and there is no outcomes data. A study presented at HRS tried to give us outcome data but it simply compared patients who got LBB area pacing with those who got a standard RV lead. I hope regular listeners see the problem here. You can’t do that and expect to get an unbiased comparison. If you want to know how two pacing techniques stack up, you must randomize patients. Randomization balances out all the known and unknown baseline characteristics. When you compare patients without randomization, you will get a biased sample. That is because a doctor chose to use the new or the standard technique.

Indeed, this study showed that LBB pacing crushed standard pacing, but it surely was biased. I know this because LBB area pacing reduced mortality by about 50%, and no proponent of LBB pacing would suggest that it is that good. Of course, sicker patients received the standard RV pacing lead and they did worse because they were sicker.

Medical Evidence

A research letter published in JAMA-Internal Medicine, first author, Todd Lee, from McGill University, exposes the lack of rigor in the adjudication of science. This is not a good news story, but it is an important story. And there is an important take-home.

The researchers tallied the number of citations of a (famously) retracted study. Back in May of 2020, The New England Journal of Medicine (NEJM) published a paper that showed no increased risk for in-hospital death with the use of angiotensin-converting-enzyme (ACE) inhibitors or angiotensin-receptor blockers (ARBs) in hospitalized patients with COVID-19. The data came from a nebulous database called Surgisphere. Internet sleuths and Twitter scientists, not peer-reviewers and editors at the top medical journal, proved the data was broken and within 6 weeks, NEJM retracted the paper. A week later, another study from the Surgisphere database, this one on hydroxychloroquine and published in the Lancet, was also retracted for broken data.

The Canadian team was interested in whether this retracted NEJM paper was still being cited in other papers. The sad answer was that over the past year, 934 published papers cited the obviously debunked study.

  • Of these 934, 652 were verified citations in peer-reviewed journals.

  • Most citing articles (355 [54.4%]) were published 3 months or longer after the retraction; 181 (27.8%) were published 6 months or more.

  • In May 2021, nearly a year after the article was retracted, it was cited 21 times.In 17 papers, the data from the retracted article was incorporated in a new analysis. Let me repeat. There they sit, for anyone with a computer connected to the Internet to find, 17 papers that include known fraudulent data.

This is such an important research letter. The take-home message should not be cynicism. Instead, this work amplifies the necessity for keeping and embracing skeptical priors. Science is hard. mRNA-vaccine-like magic bullets are rare.

The incentive of science publishing is attention. Just as we consider dualities of interest in industry-funded studies, we must also consider the attention incentive structure of science.

The retracted studies got by peer and editorial review because they were attention-grabbing in their content and in their findings. More mundane studies and those that find nonsignificant results are more likely to remain in the file drawer and never be seen. Good science that finds nonsignificant results may receive this common message:

“In comparison with the many other papers we have to consider, this one is a lower priority for us.”

The purpose of this podcast is to promote critical appraisal –call it a neutral Martian’s view of evidence. To do critical appraisal you have to approach science-done-by-humans with a skeptical but not cynical point of view. Thank you, Todd Lee and colleagues, for reminding us of this important message.

Doctors in Unions?

My colleague Melissa Walton-Shirley wrote a provocative opinion piece on why and how doctors should unionize. This topic provokes deep thought about the role of doctors in the current state. I have such mixed feelings. Read the piece. Think about the issue. Especially if you are young.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.