ICRI: Information-Theoretic Cardiovascular Reserve Index — Discovery Record v1.0

While computing Shannon entropy metrics on prime gap sequences, we applied the same analysis to RR-interval data from the MIT-BIH Arrhythmia Database (46 records). An unexpected pattern emerged: the ratio of conditional entropy to mutual information of successive RR differences — h2_cond / MI2 — decreases monotonically with arrhythmia severity across five clinical categories. The metric is computed from standard RR sequences, requires no special hardware, and is an exact Shannon quantity rather than an approximation. This is a preliminary empirical observation, not a clinical study.