It is not altogether off-topic Ella. There is more than one report of Nicholas II suffering chest pain. If I recall correctly another, again, comes from his own diary when he stated suffering a severe, crushing pain in the chest while he was out for a Sunday afternoon walk ' on the

road'. Perhaps someone else will recall this entry with greater accuracy. I am not aware of any diagnostic tool which aided the diagnosis of myocardial infarction in 1917. The diagnosis was symptom-led by which time the patient was usually dead. They certainly did not have access to electrocardiogram machines and etc.
I don't think Bear is necessarily chasing geese - wild or domestic - here. Historically, perhaps sufficient attention has not been paid to the physical and mental state of the Tsar by March 1917. This is understandable in view of the cataclysmic events exploding all around. I think there is every chance Nicholas II did suffer at least two heart attacks in the lead up to the abdication. He was within the 'perfect' age range. The description of 'crushing' type pain is typical. The kind of stress to which he exposed himself would have been sufficient to induce an arrest in the heart of an elephant. In 1917, no medic would have advised against physical activity of the kind - digging and shovelling snow. In fact, given Nicholas' history, he would have found these activities positively therapeutic.
There is also evidence - some of which is cited here - of some form of mental collapse. It would have been all the more extraordinary had the Tsar not manifested mental/emothional symptoms. Of course his doctor and advisers would insist their 'boss' was just a bit tired - what else would you expect? 'The emperor is in the midst of a serious physical and mental collapse'?
In response to the subject of the thread 'Who Betrayed Nicholas II' - a number of characters have been enumerated, but perhaps sufficient attention has not been paid to the meaning of the word 'betray(ed)'. To betray is a deliberate, knowing act of deception. I would be tempted to say that, in his position as Emperor, Nicholas unwittingly betrayed Russia, but it is impossible to 'unwittingly betray'. To betray is an act of commission.
It might be easier, for the purposes of this thread, to look at who, (according to the dictionary definition) committed an act of treason against the Emperor: who was false or disloyal towards the Emperor: who revealed, against their will or desire, their opposition to the Emperor: who deliberately deceived their Emperor?
tsaria