Think Like Cardiologists: What Did They Learn in the Past 12 Months That Primary Care Should Know?

Primary care clinicians, by necessity, are jacks of all trades. Keeping up with changes in virtually every specialty and translating that new knowledge into busy primary care practice is a gargantuan task. This likely helps explain why, on average, it takes 17 years for medical advances to be widely implemented.^[1]

Our new series aims to bring primary care clinicians a one-page crib sheet of the five articles subspecialist members—across all specialties—found to be most important, as evidenced by what they chose to read in the last 12 months.

First up: cardiology. Here's what cardiologists focused on:

Substudy Provides Clues to Digoxin Threshold for Atrial Fibrillation

A subanalysis of the ARISTOTLE trial^[2] provides some clues about safe use of this old drug for atrial fibrillation (AF).

Digoxin is prescribed for almost 30% of AF patients worldwide despite guidelines^[3,4] indicating that it should rarely be used. Gaetano M. De Ferrari, MD, one of the study authors, emphasized that for every 0.5-ng/mL increase in digoxin level, there is a 19% or 20% increase in mortality. He stressed using extreme caution with digoxin, particularly in women.

Take-home message. Use digoxin only as a last resort and only after trying all other means to control rate and improve symptoms. If digoxin is prescribed, maintain blood levels at ≤1.1 ng/mL.

DOAC Dos and Don'ts

Drs Robert McBane, Ariela Marshall, and Gayatri Acharya of Mayo Clinic discuss the direct-acting oral anticoagulants (DOACs).

For the first time in 50 years, we have medications for anticoagulation that do not need to be directly monitored and have very few food or drug interactions. DOACs include two classes:

• Direct thrombin inhibitors: dabigatran (Pradaxa®)

• Direct factor Xa inhibitors: rivaroxaban (Xarelto®), apixaban (Eliquis®), edoxaban (Savaysa®), and betrixaban (Bevyxxa®)

There are subtle differences between the drugs with respect to metabolism, efficacy, and rates of bleeding. Yet all are rapid acting and have relatively long half-lives. Bleeding reversal is a concern; idarucizumab has been approved to reverse the effects of dabigatran, and others are in the pipeline.

Several DOACs are recommended for stroke prevention in patients with nonvalvular AF.^[5] They are the preferred first-line agents for treatment of deep venous thrombosis or pulmonary embolism.^[6] Refer to product labeling for approved indications.

Take-home message. Adherence to DOAC therapy is critical. "[E]nsure that patients are both filling the prescription and taking the medication," instructed Dr McBane.

Vitamin D for Statin-Related Myalgia

About 1%-2% of statin users experience myalgia to a degree that may preclude use of this effective agent. Vitamin D deficiency is also associated with similar myalgia. While the mechanism of statin-associated myalgia is not clearly elucidated, it has been proposed that statins may decrease vitamin D levels. The actual effect of statins on vitamin D levels is unclear; clinical trials and observational studies have produced mixed results. In fact, a recent meta-analysis found increased vitamin D levels in statin users.^[7]

If statins do not lower vitamin D levels per se, could it be that patients with low levels are predisposed to experience myalgia if prescribed statins? A review of the evidence concludes that the data are conflicting, with not all studies finding an association between low vitamin D and risk for myalgia. However, some uncontrolled studies have suggested that in statin-treated patients with muscle symptoms and low vitamin D levels, supplementation may be effective.

Consider using the American College of Cardiology's Statin Intolerance Tool to help you treat your patients.

Take-home message. Vitamin D supplementation may be worth considering in patients with low vitamin D levels who are experiencing statin-related myalgia.

Statins for Primary Prevention in the Elderly

Results of a secondary analysis of ALLHAT-LLT show no benefit of statins for primary prevention in older adults.

Back in 2002, the ALLHAT-LLT trial, an unblinded, randomized, 6-year trial of pravastatin versus usual care in patients with hypertension and dyslipidemia found no significant reduction in all-cause mortality or coronary heart disease events with the statin.

The recent post hoc analysis of the almost 3000 participants ≥65 years of age suggested that statins for primary prevention do not lower the risk for cardiovascular (CV) or all-cause mortality in older adults with CV risk factors. While not statistically significant, there was a trend towards increased all-cause mortality in patients ≥75 years taking statins. The trial has well-recognized limitations, and experts cautioned that the trial was not originally designed to study statins in older adults and that the analyses are underpowered.

Best bet is to refer to the latest guidelines for primary prevention of cardiovascular disease (CVD).^[8]

Take-home message. Statins may have significant benefit in appropriately selected patients; older adults may not be those patients.

The Saturated Fat Wars

In response to a perceived trend in consumer media touting the benefits of some saturated fats (eg, whole milk, butter, coconut oil), the American Heart Association (AHA) released an advisory on dietary fats and CVD, reiterating that individuals should replace saturated fats with poly- and monounsaturated vegetable oil to help prevent heart disease.^[9]

The AHA's position was not without its critics, who argued that other epidemiologic studies and expert reviews found weak to nonexistent evidence for the link between saturated fat and heart disease. In a detailed rebuttal on Medscape, Nina Teicholz, author of The Big Fat Surprise, and cardiologist Eric Thorn charged that the AHA cherry-picked their data and ignored significant evidence that shows no association between the consumption of saturated fats and coronary heart disease.

We've gathered a range of opinions in a special report on saturated fats and CVD.

Take-home message. The weight of medical guidance supports a consensus that a diet rich in whole foods and low in sugar/processed foods is likely best.

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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.

Cite this: Think Like Cardiologists: What Did They Learn in the Past 12 Months That Primary Care Should Know? - Medscape - Mar 09, 2018.