A lack of visible P waves preceding QRS complexes suggests a lack of sinus beats; this may occur with sinus dysfunction or in the presence of fibrillation or flutter waves. The P wave may also be hidden within the QRS complex. … Absence of P Waves. AtriaVentriclesAtrial FlutterRegular ~300bpmRegular ~150bpmThe P Wave | ECG Basics – MedSchool medschool.co › tests › ecg-basics › the-p-wave