Exhibit 99.31 MBNA MASTER CREDIT CARD TRUST II SERIES 1997-N KEY PERFORMANCE FACTORS July 31, 1999 Expected B Maturity 11/15/00 Blended Coupon 5.1256% Excess Protection Level 3 Month Average 6.41% July, 1999 6.33% June, 1999 5.28% May, 1999 7.61% Cash Yield 18.74% Investor Charge Offs 4.97% Base Rate 7.44% Over 30 Day Delinquency 4.84% Seller's Interest 9.75% Total Payment Rate 14.54% Total Principal Balance $45,698,903,036.29 Investor Participation Amount $900,000,000.00 Seller Participation Amount $4,456,383,517.80