I've never heard that being clot related. Often your numbers can vary because if how tight or loose the cuff is, even in the same arm.

It can also vary due to the distance from the heart. The heart creates your systolic blood pressure (the top number). That measures how hard the heart has to pump against resistance in the circulatory system to get blood all the way through the arteries. The diastolic pressure (lower number) is the result of the elasticity of the artery walls in the body, which actually help "push" the blood along even between heartbeats. This is why if your lower number is high, your doctor worries about "hardening of the arteries". So the further away from the heart, the more the pressure imparted by the heart drops (this makes sense, right)? In general, it doesn't matter which arm the pressure is taken in, they should both be pretty close to each other. Some people have problems with the arterial flow to one arm or the other, either because one artery is narrower at birth or due to injury or because of plaque buildup or a clot in the artery. In those people, the readings will be drastically different. 120/80 and 115/75 are not big differences. 120/80 and 80/60 are. So it's a matter of degree how important a difference in blood pressure in opposite arms is. If you're concerned, ask your doctor.

Yeah that's a good point. The concern is when the readings are really disparate. One thing too. When I'm all mentally jacked up when having my blood pressure checked, it does effect the reading. So bsmith, remember that too.

I learned something new about the distance from the heart thing. Makes total sense!

To add to what was said already, I think in this case, when you just ask could it be attributed to clots, the word 'clots' might be too general to be able to answer. If you're asking whether PE would affect that, I tend to think no. That might increase your pulmonary BP, and I experienced lower than normal systemic BP after diagnosis with PE, but I can't think of any reason why it would cause any significant difference between arms. I'm not saying it's impossible, I just can't think why it would but maybe a doctor would know something more.

If you wonder whether a DVT in your arm could cause a significant difference in the arms, I'd think it would be possible, but I don't really know. It just seems reasonable to me that if there were a DVT in one, it could possibly increase arterial pressures in that arm, since the blood has some impediment to proper flow.

I think if you are getting consistent and significant (as in, the second example ljhcnmt gave) differences in your arms, then it's best to talk to your doc about it. Sooner rather than later if you're getting it combined with any unusual chest pain (out of the ordinary for whatever you're used to from the PE).