COMMENTARY

Aug 14, 2020 This Week in Cardiology Podcast

John M. Mandrola, MD

Disclosures

August 14, 2020

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 14, 2020, John Mandrola, MD comments on the following news and features stories.

COVID Update

Yesterday we hit 5.4 million cases in the United States. US deaths two weeks ago were 155,000 and this week they are 170,000, so the rate of rise of 1.04x per week is solidly on a plateau.

The news here can be summed up in a Tweet from a New York Times reporter:

“Reported coronavirus deaths yesterday: • France: 0 • United Kingdom: 0 • Canada: 4 • Germany: 6 • Italy: 6 • United States: 1,450.”

COVID Cardiac Effects

A brief follow-up note on the importance of critical appraisal. Two weeks ago, I reviewed a small observational study from Germany on the use of cardiac magnetic resonance imaging in patients recovered from COVID-19.

The study was interesting but did not at all definitively say much about long-term cardiac effects from COVID-19. What’s more, there were probably reporting errors in the data. That did not stop the massive media coverage. In these news reports, the extremely limited study was cited as a reason to cancel college sports. But this study was nowhere near definitive enough influence any policy decision. There are tons of reasons to cancel college sports in the midst of the pandemic. This study should not be one of them.

Flawed studies with provocative headlines just take on a life of their own in the media. Hydroxychloroquine got going like that. The flawed JACC anticoagulation study did too. If there are any journal editors who listen, please, help the media by forcing cautious conclusions in the abstract, and press releases.

Obesity

I came across two interesting takes on obesity and COVID-19. The Annals of Internal Medicine published a retrospective cohort study from Kaiser hospitals in Southern California. It was a large study of about 7000 patients with COVID-19. They found a definitive J-shaped association between body mass index (BMI) and risk of death, after adjusting for obesity related complications such as diabetes, heart disease, etc. This risk was most striking among those aged 60 years or younger and men; different from previous observations: Black or Latino race/ethnicity was not associated with increased death.

Yesterday I saw a similar study published in the Proceedings of the National Academy of Sciences. This was a community dwelling general population in the United Kingdom with linkage to a national registry on hospitalization for COVID-19. The authors studied the association between BMI and waist to hip ratios and COVID-19 hospitalization. Again, they found an upward linear trend with increasing BMI, and the associations were little affected after adjustments for a wide range of co-variables. A similar pattern emerged for waist to hip ratios.

Another article, from Kaiser Health News, published on the theheart.org| Medscape Cardiology surveyed the literature on the effects of vaccines in the presence of obesity. The author cited a handful of studies showing that obesity can be a mitigating factor for efficacy of flu vaccine. This was news to me. I did not know that obesity might affect immunogenicity of vaccines. The bioplausibility argument goes to the notion that chronic obesity and its cardiometabolic manifestations create a state of chronic inflammation.

A study in an obesity journal in 2017 found that influenza-vaccinated obese adults were twice as likely as adults of a healthy weight to get flu. Smaller studies have also suggested obesity mitigates vaccine response in Hepatitis B and A. The point is, this could be a factor in the future.

Heart Failure Therapy

We all know about the guideline directed therapies like ACEs, ARBs, sacubitril/valsartan, beta-blockers, and MRAs (mineralocorticoid receptor antagonists). But lurking in our blind spots sometimes is the simple thing: loop diuretics.

I’ve been sitting on our peer review committee for 20 years and one of the most common reasons to review a case is a readmission for heart failure in a person not sent home on a diuretic. An observational registry-based study published in JACC covered this issue. Multiple authors used data from the Medicare-linked OPTIMIZE HF registry to determine the relationship between loop diuretic use at discharge and clinical outcomes in patients with heart failure.

They started with about 25,000 older patients. They excluded patients who came in taking diuretics, those on dialysis, and those discharged on thiazide diuretics. That left about 8000 patients of which 70% received a loop diuretic and 30% did not. The authors did propensity matching of about 70 baseline patient characteristics and ended up with 2200 matched patients who were given or not given the diuretic at discharge. Heart failure readmission within 30 days and mortality were significantly lower among the group given diuretics.

The authors conclude that “these findings provide new information about short-term benefits associated with diuretic use.” But this is yet another classic case of likely confounding. The doctor who gets in trouble for not sending a heart failure patient home on a diuretic likely did so because he or she was worried about something: volume depletion, electrolyte issues, low blood pressure.

Similarly, in the observational study, even though the authors match patients on 70+ characteristics, this is still a non-randomized comparison. The reason a patient did or did not get a diuretic was not random, it was the decision of a thinking clinician. Thus, it’s highly likely that unmeasured confounders explain why patients not discharged on diuretics did worse. The authors discuss these limitations in the discussion but their conclusions imply causal connections.

Impella and COVID-19

Early this month the US Food and Drug Administration (FDA) gave emergency use authorization (EUA) for the Impella mechanical assist device. The EUA specifically covers temporary use of if the device for left ventricular unloading in patients with heart failure who develop pulmonary edema or late decompensation from myocarditis while on ECMO support. A couple of months ago, the FDA had also given EUA for the right sided Impella for COVID-19 patients who have right heart failure from PE.

I don’t quite get this. All over Twitter, I see major thought leaders on COVID-19 calling for the FDA to get moving on approval of at-home COVID tests. But here we have FDA giving EUA for a tremendously expensive device that has yet to pass muster in a proper RCT in pure cardiac patients, never mind those with viral infections.

I am not a policy wonk, but this EUA seems likely related to two factors: one is marketing. Get the Impella name out there. The other reason seems likely related to re-imbursement. Impellas are sitting on the shelves at hospitals. If a doctor thought it might help, he or she could use it. But without a specific indication, the hospital could not bill for it. Now, with an EUA, the hospital can get paid.

I am sorry to sound cynical, but the idea of FDA rushing to give ABIOMED new indications for an unproven device in a novel disease bothers me. I am happy to be corrected about this cynical tone. Let me know.

Fitness and AF Ablation

The Cleveland Clinic EP group has published a small but nice study looking at the association of cardiorespiratory fitness (CRF) and outcomes after AF ablation. Heart Rhythm published the observational study on nearly 600 patients who had an exercise stress test before the ablation. Patients were divided into three groups: low, adequate, and high fitness.

During a mean follow-up of 32 months after ablation, arrhythmia recurrence was observed in 79% of patients in the low CRF group, 54% in the adequate CRF group, and 27.5% in the high CRF group ( P <.0001). Rates of repeat arrhythmia-related hospitalization, repeat rhythm control procedures, and need for ongoing antiarrhythmic therapy were significantly lower in the high CRF group ( P <.0001).

This study confirms the work of Adrian Elliot and Prash Sanders from Adelaide. Their study, called CARDIO-FIT, published in JACC, also found that among obese individuals with AF, baseline CRF was a strong predictor of freedom from arrhythmia, antiarrhythmic medications, and ablation. The authors also cite the recently published HUNT study, a Norwegian observational study of about 1100 patients with AF, which found that with each MET increase in CRF, all-cause mortality, cardiovascular morbidity, and cardiovascular mortality were significantly reduced. While none of these studies are RCTs, they are strongly suggestive of an important modifiable risk factor before ablation.

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