Results
Baseline Characteristics
Baseline characteristics are summarized in Table 1. The degree of AS and AR, length of hospital stay, and length of ICU stay did not significantly differ between the two groups (P > 0.05 for both). Of the 38 patients reviewed, 30 patients (75%) received autologous pericardium and 8 (20%) received CorMatrix material.
Aortic Stenosis
For the entire cohort (N=40), the peak trans-valvular gradient significantly decreased between pre-operative and post-operative assessments (P =0.0017), with no significant change observed at outpatient follow-up (P=0.36). In the pericardium group, the peak trans-valvular gradient also significantly decreased pre- and post-operatively (P= 0.012), with no significant change at outpatient follow-up (P=0.12). In the CorMatrix group, only 4 patients had AS at baseline; therefore, there was insufficient data for between-group tests (Table 2).
Aortic Regurgitation
For the entire cohort, the proportion of patients with moderate to severe regurgitation significantly decreased between pre-and post-operation (P<0.0001). In the pericardium group, 28 (93%) had moderate to severe AR at baseline which improved to 11 (37%) post-operatively and increased to 21 (70%) at time of follow-up. In the biomaterial group, 8 (100%) had moderate to severe AR which improved to 3 (38%) post-operatively and increased to 7 (88%) at time of follow-up (Table 2, Figure 2).
Freedom from Re-Operation
At five years after AVR, freedom from reoperation was significantly poorer in patients receiving CorMatrix (12.5%) compared to patients receiving autologous pericardium (62.5%) (P = 0.01) (Figure 1). 16 patients (42%) underwent a re-operation of the aortic valve, with 10 patients requiring re-operation due to severe or recurrent AR and 6 patients with severe, critical, or worsening AS. 6 patients underwent the Ross procedure, 2 underwent AVr with autologous pericardium, 5 underwent AVr with the Carpentier Edwards Valve, and 3 underwent AVr with the Resilia Bovine Pericardial Valve. The mean length between the initial operation and re-operation was 1390 days.
The most common reason for reoperation in the autologous pericardium group was for the repair of moderate to severe aortic regurgitation. In many of the patients, the non-augmented leaflet was prolapsing into the LV outflow, causing the AR. None of the patients receiving CorMatrix had severe AR post-operatively, however, 88% of them developed severe AR at recent-follow up (Table 2). Consequently, severe AR was the most common reason for reoperation in the CorMatrix group. Many had left and or right coronary cusps that were retracted with deformed and thickened edges. There was also lack of coaptation of the stiffened and retracted leaflets, necessitating the need for reoperation. Some cases also showed tears and delamination in the patch.