Published in the April 2019 issue of Todays Hospitalist
IN RESPONSE to “Tuning up your heart failure patients at discharge” (February): The article suggests switching the patient’s metoprolol tartrate 25mg BID to carvedilol 6.25mg BID based on the COMET trial in 2003. You quote the source, Ronald Witteles, MD, as saying, “Unless they have a very good reason not to, the vast majority of patients with systolic heart failure should be on carvedilol, not metoprolol.”
But this is erroneous because metoprolol tartrate has never been shown to help in systolic heart failure. The only three beta-blockers that have been shown to help in systolic heart failure are metoprolol succinate, carvedilol and bisoprolol. Metoprolol succinate is the long-acting version of metoprolol.
Furthermore, the non-selective carvedilol can worsen symptoms in COPD and contribute to brittle diabetes. Lastly, the patient in the vignette is on only 10mg of lisinopril. Carvedilol lowers blood pressure more, and if the patient was on only 10mg of lisinopril, that means that blood pressure was an issue. Unlike beta-blockers, you can titrate ACE inhibitors/ARBs to maximum quickly.
~ Michael Saul Lundin, MD
Dr. Witteles responds:
Thank you Dr. Lundin for your interest in this topic.
Regarding your comments: While it is true that metoprolol succinate— rather than metoprolol tartrate—is the approved form of metoprolol for systolic heart failure, that is only because the trial that led to its approval (MERIT-HF, published in 1999) chose metoprolol succinate to be tested. There is no plausible reason to believe that the succinate form is inherently superior to the tartrate form and, for better or worse, you find many patients on metoprolol tartrate for this indication.
We have only the data that we have. The only trial comparing beta-blockers for systolic heart failure (COMET) compared metoprolol tartrate to carvedilol, which showed a large survival advantage for carvedilol. As such, for most systolic heart failure patients, carvedilol should be the preferred choice.
And while patients with severe reactive airway disease may not tolerate beta-blockers, or may not tolerate a less selective beta-blocker like carvedilol, this does not apply to most COPD patients. The concerns about beta-blockers and diabetes have long ago been debunked and in fact carvedilol has more favorable effects on glycemia than metoprolol.