Conclusion
This study evaluated characteristics associated with mitral valve repair
rates and 30-day mortality for degenerative MR, focussing on the impact
of procedural caseload. It conclusively demonstrates that within the
Australian cohort, annual surgeon caseload was strongly associated with
repair rate, with hospital caseload less strongly but also associated
with higher repair rate. Surgeons with an annual volume of
>20 demonstrated the highest odds of repair, approximately
four times that of surgeons performing ≤5/year. Repair rate for these
higher volume surgeons was approximately 80%, compared with
approximately 57% in the lowest volume category. A threshold of
>10 procedures/year per surgeon was defined as a
statistically significant cut-off to improve the odds of repair, though
above this threshold, greater volume was generally associated with
higher odds of repair, particularly >20/annum. For
hospitals, the same threshold of >10 procedures was
statistically significant for improving the odds of repair, though the
caseload above this cut-off did not appear to matter. Repair rate for
hospital caseload ≤10/annum was 52%, climbing to approximately 71% for
hospitals above this threshold. This study, therefore, demonstrated that
to maximise the likelihood of repair for degenerative MR, individual
hospitals and surgeons should be performing more than 10 such procedures
annually.
Additionally, this study demonstrated that in the Australian cohort,
wherein unadjusted 30-day mortality rate for repair was 1.18% and
2.75% for replacement, mitral valve repair conferred a significant
30-day survival advantage when adjusting for age, gender and procedural
volume. Although mortality was not significantly affected by surgeon and
hospital procedural volume, unadjusted data nonetheless suggests that
higher volumes may reduce mortality rates.
Finally, this data provided support for the consideration of mitral
valve surgery as a subspecialty within cardiac surgery. Both for
higher-complexity degenerative pathology, as well as for the
asymptomatic patient in whom the guideline expected likelihood of
durable repair must be high or in excess of 95% [2,3] such patients
should be considered for referral to higher volume surgeons. This may
therefore require surgeon inter-referral, as well as encouragement of
such referral patterns by Cardiologists to mitral subspecialist
surgeons.