| Altitude (m) | People of investigation (cases) | Cardiothoracic ratio (%) |
| Plain control | 220 | 0.494 ± 0.018 |
| 3000 - 3750 | 200 | 0.498 ± 0.023(1) |
| 3751 - 4500 | 120 | 0.499 ± 0.024(1) |
| >4500 | 197 | 0.504 ± 0.023(1) |