An equal compression-ratio comparison of beat-to-beat and SAPA2 compression techniques

To adequately compare beat-to-beat substraction (BBS) and scan-along polynomial approximation #2 (SAPA2) electrocardiogram (ECG) direct compression methods, the authors applied both techniques to fifty randomly selected ECG segments from the MIT compression test database. The parameters of both techniques were adjusted to produce equal compression ratios close to 6.5 for each segment. After compression, SAPA2 segments were reconstructed using a cubic spline, and BBS segments with linear interpolation. Unlabeled plots of the original segment and both reconstructed segments in random order were graded for fidelity and clinical accuracy by a cardiologist blind to the nature and strategy of the two compression techniques. BBS was graded higher than SAPA2 in 64% of segments, SAPA2 better than BBS in 14%. Mean absolute errors and percent root-mean-square differences were nearly equal