No, L-carnitine isnt bad for your heart
10.1016/j.fct.2008.11.013 48 EllulP.RosenzwajgM.PeyreH.FourcadeG.Mariotti-FerrandizE.TrebossenV.et al (2021)
Dietary Potassium During Treatment Patients do not need to eliminate dietary potassium, but eating a high-potassium snack, such as a banana, avocado toast, or a large portion of lentils, right before bed on top of spironolactone adds marginal risk
doi:10.1097/grf.0000000000000155 Creasy SA, Lang W, Tate DF, Davis KK, Jakicic JM
View Material Safety Sheet
However, human thyroid tissue has significantly fewer GLP-1 receptors on C-cells compared to rodent thyroid tissue, which likely explains why this risk has not materialized in human clinical data