P3448Influence of severity of pectus excavatum as indicated by the Haller Index on actual heart compression and ECG findings

Abstract Background Pectus excavatum (PEX) is a depression of the sternum relative to the costal cartilages. The Haller index (HI) is an anatomical indicator of the severity of PEX that is calculated from CT. Purpose We evaluated the influence of anatomical severity of PEX as indicated by HI on the severity of actual heart compression and ECG findings Methods A total of 28 patients (23 males; 20±19 years) with PEX underwent unenhanced CT and ECG. On CT, HI and degree of compression of right (RA) and left atria (LA) were evaluated simultaneously. Results As indicated by CT, the mean HI was 5.80±2.34. We observed 7, 15, 5, and 1 patient with none, mild, moderate, or severe RA compression, respectively. In addition, we observed 8, 13, 4, and 3 patients with none, mild, moderate, or severe LA compressions, respectively. The mean HI was calculated as 4.28±0.92, 5.40±2.01, 6.85±1.81, and 9.61±0.00 in patients with none, mild, moderate, or severe RA, respectively, and the findings were significant (P=0.021). The mean HI was calculated as 4.17±0.91, 5.97±2.23, 5.95±1.51, and 6.69±2.93 in patients with none, mild, moderate, or severe LA compression, respectively, although the findings were not significant (P=0.145). On ECG, a P wave with a negative portion >1 mm in depth and >40 ms in duration in the V1 lead, complete or incomplete right bundle branch block (RBBB), sinus arrhythmia, or right-axis deviation of a QRS wave were diagnosed in 23, 10, 8, and 6 patients, respectively. The HI between patients with (n=23) and without (n=5) a negative portion of the P wave in the V1 lead showed a significant difference (6.45±2.43 vs. 4.62±1.68; P<0.05). The correlation coefficient between absolute values of the maximum negative portion of the P wave in the V1 lead and HI was 0.36 (n=28). The HI between patients with and without a complete or incomplete RBBB showed a significant difference (6.98±2.43 vs. 5.14±2.07; P<0.05). The HI between patients with and without a sinus arrhythmia did not show a significant difference (5.45±2.66 vs. 5.94±2.25). The HI between patients with and without a right axis deviation on a QRS wave also did not show a significant difference (4.76±1.53 vs. 6.08±2.64). The inter-observer agreement of HI between the two observers was 0.978. Haller index and heart compression on CT Conclusion In patients with PEX, compression of RA on CT, a negative portion of the P wave in V1, complete or incomplete RBBB, sinus arrhythmia, and a right axis deviation on a QRS wave are common. The degree of compression of RA on CT, negative portion of the P wave in the V1 lead and complete or incomplete RBBB on ECG are associated with anatomical severity as indicated by the HI. However, our results showed that HI severity was unrelated to either the degree of compression of LA on CT, or sinus arrhythmia and right-axis deviation of the QRS wave on ECG. These observations may be due to variation of location of maximum sternum depression, such as high- or low-positioned dominant-type compressions.