In the NINDS rt-PA trial, there was no interaction between hyperdense MCA sign and treatment for outcomes at 3 months measured by any of the 4 clinical scales (mRS score 0 1, NIHSS score 0 1, Barthel Index score 95, Glasgow Outcome Scale score 0 1) or for death.170 In IST-3, no significant interaction of the hyperdense MCA sign with benefit of alteplase measured by the Oxford Handicap Score at 6 months was observed.171,172 See Table XXXVIII in online Data Supplement 1. 3.5.5. Bleeding Risk COR LOE New, Revised, or Unchanged Given the extremely low risk of unsuspected abnormal platelet counts or coagulation studies in a population, it is reasonable that urgent IV alteplase treatment not be delayed while waiting for hematologic or coagulation testing if there is no reason to suspect an abnormal test. IIa B-NR Recommendation and COR unchanged from 2015 IV Alteplase. LOE amended to conform with ACC/AHA 2015 Recommendation Classification System. In otherwise eligible patients who have previously had a small number (1 10) of CMBs demonstrated on MRI, administration of IV alteplase is reasonable. IIa B-NR New recommendation. In otherwise eligible patients who have previously had a high burden of CMBs (>10) demonstrated on MRI, treatment with IV alteplase may be associated with an increased risk of sICH, and the benefits of treatment are uncertain. Treatment may be reasonable if there is the potential for substantial benefit. IIb B-NR New recommendation. CMBs are common in patients receiving IV alteplase, occurring in 15% to 27%.89 94 No RCTs of IV alteplase in AIS with baseline MRI to identify CMBs have been conducted, so no determination of the effect of baseline CMB on the treatment effect of alteplase with CMB is available. 