It is important NOT to give beta-blockers if there are signs of cardiogenic shock such as hypotension or pulmonary edema on chest x-ray. Bradycardia with a heart rate < 60 beats per minute or high grade AV blocks are also contraindications. In asthmatics with significant wheezing and elevated heart rates during an acute coronary syndrome, beta-blockers should be avoided and non-dihydropyridine calcium channel blockers (diltiazem, verapamil) can be used instead.