Cannon ‘a’ wave in venous waveform is suggestive of
The venous waveform is divided into several distinct peaks. The 'a' wave reflects right atrial presystolic contraction and occurs just after the electrocardiographic P wave, preceding the first heart sound (S). A prominent 'a' wave is seen in patients with reduced right ventricular compliance; cannon 'a' wave occurs with atrioventricular (AV) dissociation
AV dissociation
Atrial fibrillation
Tricuspid incompetency
All of the above