Table 2.
Characteristics of the anatomical isthmuses according to the CV classification
| Total | SC-AI | Non–SC-AI | P-value | |
|---|---|---|---|---|
| Total AI | 27 | 11 | 16 | |
| Width (mm) | 14.5 (11–26.5) | 11.5 (10.7–15.2) | 21 (11.2–29.5) | 0.22 |
| Isochrones/cm | 3 (1.5–4) | 4 (4–5) | 2 (1–3) | <0.001 |
| DZ | 10 | 10 | 0 | <0.001 |
| Conduction velocity m/s | 0.6 (0.15–1.35) | 0.15 (0.11–0.18) | 1.25 (0.66–1.52) | <0.001 |
| AI1 | 10 | 0 | 10 | |
| AI1 width (mm) | 28 (13.5–31) | NA | 28 (13.5–31) | NA |
| Isochrones/cm | 1 (1–2) | NA | 1 (1–2) | NA |
| DZ | 0 | NA | 0 | NA |
| Conduction velocity m/s | 1.25 (1–1.5) | NA | 1.25 (1–1.5) | NA |
| AI2 | 3 | 1 | 2 | |
| AI2 width (mm) | 7 (6–20) | 6 | 8–20 | 1 |
| Isochrones/cm | 3 | 5 | 2 | 0.33 |
| DZ | 1 | 1 | 0 | 1 |
| Conduction velocity m/s | 1.3 | 0.4 | 1.3 | 1 |
| AI3 | 14 | 10 | 4 | |
| AI3 width (mm) | 11 (11–16) | 11.5 (11–15.5) | 14 (11–16.5) | 0.6 |
| Isochrones/cm | 4 (3–4.25) | 4 (4–5.5) | 3 (2–3) | 0.026 |
| DZ | 9 | 9 | 0 | 0.005 |
| Conduction velocity | 0.24 (0.12–0.7) | 0.15 (0.09–0.24) | 0.7 (0.63–1.2) | 0.002 |
In general, SC-AIs are coincident with DZ, presenting an inverse relationship between isochrones/cm and CV. Slow conduction anatomical isthmuses are present in the pre-defined IAs and are correctly identified by DZ.
AI, anatomical isthmus; CV, conduction velocity; DZ, deceleration zone (>3 isochrones/cm); SC, slow conduction.