A modular electrocardiogram recording system includes a control patch, a wearable patch configured to be electrically connected to the control patch and to be worn on a user's skin, a handheld panel configured to be electrically connected to the control patch and to be hand held by the user. The wearable patch includes one or more sensing electrodes configured to sense a first ECG signal from the user. The handheld panel includes one or more conductive pads configured to sense a second ECG signal from the user,
