Exhibit 99.21 MBNA MASTER CREDIT CARD TRUST II SERIES 1997-B KEY PERFORMANCE FACTORS October 31, 1999 Expected B Maturity 3/15/12 Blended Coupon 5.6397% Excess Protection Level 3 Month Average 5.94% October, 1999 6.10% September, 1999 5.79% August, 1999 5.93% Cash Yield 18.61% Investor Charge Offs 4.68% Base Rate 7.83% Over 30 Day Delinquency 5.07% Seller's Interest 9.14% Total Payment Rate 14.64% Total Principal Balance $47,636,626,081.62 Investor Participation Amount $1,000,000,000.00 Seller Participation Amount $4,354,806,563.13