Reply to the Editor - Maternal inappropriate sinus tachycardia during pregnancy.

Abstract

We would like to comment on the Letter to the Editor of Dr Wang on our manuscript, Management of Inappropriate Sinus Tachycardia during pregnancy (1Shah A.N. Ferreira S.W. Padanilam B.J. Prystowsky E.N. Management of inappropriate sinus tachycardia during pregnancy.Heart Rhythm O2. 2023; 4: 65-66https://doi.org/10.1016/j.hroo.2022.11.001Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar). He acknowledges that we used the standard accepted definition of inappropriate sinus tachycardia (IST) but raises the issue of whether an alternative definition of IST should be used during pregnancy. Indeed, recent data in pregnant women show that median heart rate was 82 bpm at 12 weeks gestation and rose to 91 bpm at 34.1 weeks (2Green L.J. Mackillop L.H. Salvi M. et al.Gestation-specific vital sign reference ranges in pregnancy.Obstet Gynecol. 2020; 135: 653-664Crossref PubMed Scopus (42) Google Scholar). However, the average heart rates in our patients mostly recorded in the early 2nd trimester were typically more than 100 bpm, and more importantly they were highly symptomatic with the added history of rapid and marked increases in heart rate during exertion, a classic presentation of IST. They were referred for further evaluation because their physicians considered them to have something other than the usual mild increase in heart rate with pregnancy. Dr Wang comments on the use of metoprolol to treat these very symptomatic patients, and suggests that the data on its effectiveness in non-pregnant patients remains questionable. The senior author (ENP) has a different experience and has treated scores of IST patients prior to ivabradine availability with substantial success in many using metoprolol succinate. The limiting factor for success is often the inability to use a high enough dose because some of these patients simply cannot tolerate beta-blockade therapy even at a low dose. Further, it is our experience that volume expansion and use of salt supplementation, while valuable in autonomic syndromes of hypotension, are not effective in pure IST without hypotension. Last, although one would like to avoid the use of any drug during pregnancy, metoprolol is considered safe to use if needed (3Page R.L. Joglar J.A. Caldwell M.A. et al.2015 ACC/AHA/HRS Guideline for the management of adult patients with supraventricular tachycardia: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society.Heart Rhythm. 2016; 13: e136-e221Abstract Full Text Full Text PDF PubMed Scopus (67) Google Scholar), and all our patients were treated beyond the first trimester. Risks and benefits of therapy were discussed during the shared decision making process, and all patients wanted to take metoprolol to suppress their marked symptoms. We agree that more data on IST in pregnancy, and the safety of ivabradine, would be useful and encourage others to investigate this problem. To the Editor – Maternal inappropriate sinus tachycardia during pregnancyHeart Rhythm O2PreviewShah and colleagues presented 11 patients with maternal inappropriate sinus tachycardia (IST) during pregnancy.1 Two major points are worth considering. Full-Text PDF Open Access