We have conducted a clinical trial to investigate the receptiveness and signal accuracy of our in-house light-weight single lead wearable wireless ECG device with 20 outpatients, who were suspected of cardiac rhythm issues. The receptiveness was measured via a survey score sheet while the signal accuracy was evaluated by comparing the Holter's hourly heart rate report (the gold-standard) against the ones from our device. In terms of receptiveness, a score of 8.6 indicates good patient compliance. In terms of accuracy, the mean absolute error is 1.4 bpm (beats per minute) with precision of ±1.6 bpm. In addition, measurements from both devices were found to be linearly related with coefficient of determination, r2, of 0.97. Furthermore, the limits of agreement were calculated to be +3.54 and -4.71 based on the Altman and Bland technique, which indicated good agreement for most of our measurements against the Holter device. In addition, this paper also discusses the unexpected challenges of conducting a trial on actual outpatients which can be used as a reference for similar subsequent studies.