Will smoking canibis affect a echocardiogram?

Yes. It has been reported that cannabis can lead to tachycardia[sinus] and arial arrhythmias, acute coronary syndromes, asystole, coronary vasospasm, pseudo- Wellens 'ECG patterns. Low doses leads to increase in sympathetic stimulation and high doses lead to a inhibited sympathetic activity resulting in bradycardia and hypotension. Now don't think of smoking before or even after an ECG for health