Minimally Invasive Cardiac Surgery

Minimally invasive cardiac surgery (MICS) emerged in the late 1990s as surgeons explored alternatives to full sternotomy. Early single-center reports described right mini-thoracotomy approaches for mitral valve surgery and partial sternotomy for aortic valve replacement. These initial case series demonstrated technical feasibility with potentially reduced blood loss, shorter ICU stays, and faster return to normal activities compared to conventional sternotomy. However, the field was limited by the lack of prospective randomized data.

The MIST (Minimally Invasive coronary Surgery compared to STernotomy) trial was designed as a multicenter prospective RCT comparing MICS CABG to sternotomy CABG, with quality of life and early recovery as primary endpoints. Large institutional registries and propensity-matched studies consistently demonstrated that MICS valve surgery produced equivalent surgical outcomes to conventional approaches with reduced transfusion requirements, shorter hospital stay, and improved cosmesis. A meta-analysis of observational studies comparing mini-thoracotomy to sternotomy for mitral valve surgery reported similar mortality with less blood loss and faster recovery.

Robotic cardiac surgery represented the next evolution, with adoption of the da Vinci system for mitral valve repair, CABG via LIMA harvesting, and atrial septal defect closure. Institutional series from high-volume centers demonstrated excellent outcomes, though operative times were longer and the learning curve was steep. The COMICS trial (Conventional versus Minimally Invasive Extra-Corporeal Circulation) explored reducing the inflammatory response through miniaturized perfusion circuits. Totally endoscopic approaches continued to evolve at specialized centers.

Current ACC/AHA and ESC/EACTS guidelines acknowledge MICS as an acceptable approach when performed by experienced surgeons in appropriate candidates, but do not mandate it over conventional sternotomy due to the limited randomized evidence. The emphasis remains on operator experience and institutional volume.

MICS adoption continues to grow, driven by patient demand and institutional differentiation. Right mini-thoracotomy for mitral and aortic valve surgery is established at many centers, while robotic approaches gain traction. The field lacks large multicenter RCTs comparing MICS to sternotomy for long-term outcomes. Key challenges include the steep learning curve, need for specialized training, and ensuring equivalent surgical quality across different experience levels. The MIST and MICS-CABG PRPP trials represent ongoing efforts to generate rigorous comparative evidence.