What Does NSSTTWC On My ECG Mean If I Have A History Of LVH And Now Have Left Chest Pain Relieved By Massage And Burping?

Female, 42, 62kilos, 5 3 height. 9mos ago I had my echo and ecg done, it turned out lvh. Cardio doc gave me hypertensive med. Yesterday i had my ecg again, all is well except for NSSTTWC, what does it mean? All xrays then and now are clear. But am having localized left chestpain, when I massage it I burp.