Minimally Invasive Cardiac Surgery: Where Are We Now?

Minimally invasive cardiac surgery (MICS) has moved well beyond the idea of simply making a smaller incision. Limited-access operations now encompass direct-vision, video-assisted, totally endoscopic, and robotic procedures, performed with or without cardiopulmonary bypass (CPB). Some have become established alternatives to sternotomy in experienced centers; others remain technically demanding, expensive, or supported mainly by observational evidence.

The central question is not whether we can operate through a smaller incision. It is whether we can preserve the quality and durability of the operation while reducing access-related morbidity and accelerating recovery.

Terminology: what exactly is MICS?

The term MICS is an umbrella rather than a single technique. Several frequently used abbreviations describe different operations or technologies:

Term	Meaning	Typical application
MIMVS	Minimally invasive mitral valve surgery	Mitral repair or replacement through right thoracic access
MIAVR / MI-SAVR	Minimally invasive surgical aortic valve replacement	Upper partial sternotomy or right anterior thoracotomy
MIDCAB	Minimally invasive direct coronary artery bypass	Usually off-pump LITA–LAD through left thoracotomy
MICS-CABG	Minimally invasive coronary artery bypass grafting	Limited-access coronary bypass, including multivessel surgery
TECAB	Totally endoscopic coronary artery bypass	Endoscopic, often robotically assisted, coronary bypass
TCRAT	Total coronary revascularization via left anterior thoracotomy	On-pump multivessel CABG through left anterior thoracotomy
Port-Access	Endovascular support and aortic occlusion strategy	Peripheral CPB with endoaortic balloon occlusion in its classic form

There are at least three useful ways to classify a minimally invasive operation.

By incision: upper partial sternotomy, right anterior thoracotomy, right lateral minithoracotomy, left anterior minithoracotomy, or port-based access. Right-sided approaches predominate in mitral and selected aortic valve procedures; left thoracotomy is commonly used for coronary revascularization.

By visualization and instrumentation: direct vision, video-assisted, video-directed or totally endoscopic, and robotic-assisted. These categories overlap: a robotic operation is not necessarily totally endoscopic, and a video-assisted operation can still rely substantially on direct vision.

By perfusion and cardiac state: on-pump arrested-heart surgery, on-pump beating- or fibrillating-heart surgery, and off-pump beating-heart surgery. The choice of central versus peripheral cannulation adds another important technical dimension. These distinctions matter because complications attributed to “MICS” may actually be related to perfusion strategy rather than incision size.

Why consider minimally invasive access?

Median sternotomy remains a versatile and reproducible route to the heart. It provides excellent exposure, particularly for complex or combined operations. Its disadvantages are also familiar: sternal disruption, wound complications, postoperative discomfort, and a recovery period that can limit mobility and daily activities.

Potential advantages of limited-access surgery include earlier mobilization, shorter hospitalization, and avoidance of sternal wound complications. These benefits must be weighed against longer operative or bypass times in some techniques, a substantial learning curve, more demanding cannulation and exposure, and—in robotic programs—considerable capital and running costs.

A smaller incision is not a worthwhile trade if it compromises myocardial protection, completeness of revascularization, or valve repair quality.

Patient selection is part of the operation

Preoperative screening should address both the underlying cardiac lesion and the feasibility of the chosen access route. Echocardiography defines valve anatomy, ventricular function, pulmonary pressures, and associated pathology. CT or vascular imaging can help assess the ascending aorta, aortoiliac atherosclerosis, femoral vessel dimensions, thoracic geometry, and the likely surgical working space.

Chemtob and colleagues described a conservative screening algorithm for robotic mitral surgery incorporating echocardiographic and CT findings. The study illustrates an important point: candidacy is not determined by the mitral lesion alone. Peripheral access, aortic pathology, and extracardiac anatomy may change the safest operative strategy [1].

Not every patient undergoing MICS necessarily requires the same CT protocol. Imaging should be procedure-specific and risk-based, particularly when peripheral arterial cannulation or endoaortic devices are planned. An abnormal finding does not automatically prohibit minimally invasive surgery; it may instead prompt a change in cannulation, incision, or aortic occlusion technique.

Thoracic ultrasound can provide additional information in selected patients. On M-mode imaging, the seashore sign indicates lung sliding at the examined location, while a barcode/stratosphere pattern indicates absent sliding. Neither finding alone diagnoses or excludes pleural adhesions, and neither replaces anatomical imaging when this is needed for operative planning.

Minimally invasive mitral valve surgery

Mitral surgery is one of the most developed areas of MICS. In practice, the main approaches are:

1. Right minithoracotomy under direct vision or video assistance: a working incision with conventional or long-shafted instruments.
2. Video-directed or totally endoscopic surgery: the camera provides the principal operative view, with instruments introduced through ports or a limited working incision.
3. Robotic-assisted repair: three-dimensional endoscopic visualization and articulated instruments, with additional platform and team requirements.

The techniques share an objective—high-quality valve repair without full sternotomy—but should not be treated as interchangeable in comparative studies.

What do the outcomes tell us?

Published series of minimally invasive mitral repair generally report low early mortality and acceptable complication rates. However, the wide ranges reported for stroke, bleeding, atrial fibrillation, renal injury, and late recurrent regurgitation reflect differences in case mix, definitions, experience, and follow-up. They are not adjusted head-to-head comparisons.

The evidence for limited-access mitral surgery is reassuring overall, but an important distinction remains between demonstrating feasibility, demonstrating comparable safety, and proving superiority. Olsthoorn and colleagues examined short- and longer-term outcomes in a multicenter cohort using the Netherlands Heart Registration [8]. Observational comparisons are valuable, but residual selection bias cannot be excluded.

Robotic versus video-assisted repair

Robotic platforms offer excellent visualization and wristed instrument movement in a confined operative field. Video-assisted surgery, meanwhile, can achieve complex repairs with simpler infrastructure and lower equipment requirements.

There is no established survival or repair-durability advantage for robotics over a well-performed video-assisted operation. Any differences in length of stay, bypass duration, conversion, or bleeding must be interpreted in the context of surgeon experience and the populations being compared. Tomšič and Palmen discuss both the technical promise and the unanswered questions surrounding wider adoption of robotic mitral repair [10].

Cost is another consideration. Robotic surgery may permit earlier return to normal activity or work, partially offsetting higher intraoperative costs. Nevertheless, economic results depend heavily on institutional volume, operating room efficiency, equipment utilization, and the perspective used to calculate cost. Shorter hospital stay alone does not establish cost-effectiveness.

Endoaortic balloon occlusion versus external clamping

Aortic occlusion is a particularly important technical choice in endoscopic mitral surgery. Endoaortic balloon occlusion (EABO) places an intraluminal balloon in the ascending aorta, typically through a femoral arterial route. It can combine aortic occlusion, antegrade cardioplegia delivery, and aortic root venting without an external clamp entering the operative field.

The alternative is a transthoracic external cross-clamp, usually combined with separate cardioplegia and venting arrangements. The external clamp is mechanically simpler, whereas EABO can be advantageous when port geometry or robotic instrumentation makes external clamping awkward.

Kofler and colleagues compared these strategies in minimally invasive mitral surgery [7]. The practical interpretation is that EABO is an accepted option, not a universally preferred one. The available comparisons are largely observational and do not establish clear superiority for either method in major outcomes. Careful evaluation of aortic and iliofemoral disease, reliable transesophageal echocardiographic monitoring, and familiarity with balloon migration or malposition are essential when EABO is used.

The learning curve: not just a surgeon problem

Moving from sternotomy to minithoracotomy changes exposure, instrument handling, cannulation, de-airing, and team coordination. Progression from direct vision to video-directed or robotic surgery adds further technical demands, but it is misleading to present these approaches as a universally validated three-step proficiency ladder.

Holzhey and colleagues analyzed 3,895 minimally invasive mitral operations using cumulative sum methods, demonstrating the importance of learning-curve assessment in a high-volume program [6]. Vo and colleagues likewise reported a single-center learning-curve experience [11]. These studies are reminders that case counts should be interpreted alongside case complexity, adverse events, operative efficiency, and repair quality—not treated as fixed thresholds that apply to every surgeon.

A successful program depends on the entire team: surgeon, assistant, anesthesiologist, perfusionist, scrub team, imaging specialists, and postoperative care pathway. Structured mentoring, simulation, standardized protocols, and transparent outcome monitoring are more useful than simply accumulating cases.

Minimally invasive coronary surgery: from MIDCAB to multivessel CABG

Coronary surgery presents a different challenge from isolated valve surgery. A limited incision must still permit safe conduit harvesting, high-quality anastomoses, and—where indicated—complete revascularization.

MIDCAB versus PCI for isolated LAD disease

MIDCAB commonly uses a left anterior thoracotomy to construct a LITA–LAD graft on the beating heart without CPB. Its main attraction is the durability of surgical LAD revascularization without a full sternotomy.

Recent comparisons with PCI for isolated LAD disease have reported similar survival but less repeat target-vessel revascularization after MIDCAB in the studied populations [4,9]. Some analyses also suggest advantages in myocardial infarction or composite cardiac events, although these findings should be interpreted according to study design and follow-up.

This does not make MIDCAB the default for every LAD lesion. Coronary anatomy, surgical risk, conduit suitability, anticipated durability, and patient preference remain central to decision-making.

Multivessel MICS-CABG

Multivessel revascularization through left thoracotomy is technically more demanding than isolated LITA–LAD grafting. Both off-pump and on-pump strategies have been developed. The important outcomes are not merely discharge timing or cosmetic appearance but completeness of revascularization, graft patency, repeat intervention, myocardial infarction, and long-term survival.

Gong and colleagues compared minimally invasive and conventional CABG in patients with multivessel coronary disease, reporting encouraging results for completeness of revascularization and intermediate outcomes [5]. Such evidence supports the feasibility of MICS-CABG in selected patients but should not be generalized into a claim of universal noninferiority across all centers and coronary anatomies.

TCRAT: renewed interest in on-pump thoracotomy CABG

The history of minimally invasive multivessel CABG is not a straight line from sternotomy to robotics. In the 1990s, Port-Access approaches combined peripheral CPB, endoaortic balloon occlusion, and cardioplegic arrest. Other groups developed anterior thoracotomy methods using more conventional aortic cannulation and cross-clamping. These approaches demonstrated feasibility but were difficult to standardize and disseminate.

Total coronary revascularization via left anterior thoracotomy (TCRAT) revisits the concept of full multivessel CABG through limited thoracic access with CPB and cardioplegic arrest. Its technical principles include peripheral CPB, a transthoracic aortic clamp, and controlled cardiac positioning to expose multiple coronary territories. Demianenko and colleagues review the historical development and contemporary rationale for this approach [2].

Demirkıran and colleagues reported a comparison of early and mid-term outcomes after TCRAT and conventional surgery [3]. These reports make TCRAT an important technique to watch, particularly for surgeons interested in retaining the familiar physiology and precision of arrested-heart CABG without a median sternotomy.

However, reproducibility outside experienced programs, graft durability, and longer-term comparative outcomes remain critical questions. Technical feasibility is established more convincingly than broad generalizability.

What is likely to change next?

The near-term development of MICS appears to be concentrated in several overlapping areas:

• Robotic platforms and instruments: improved articulation, optics, ergonomics, and potentially wider availability. Adoption will depend on cost, case volume, and demonstrable benefit rather than technical sophistication alone.
• Totally endoscopic procedures: continued refinement of port placement, camera systems, suturing tools, and operative workflow.
• Minimally invasive multivessel coronary surgery: MICS-CABG, TCRAT, robotic coronary bypass, and hybrid strategies combining LITA–LAD grafting with PCI in appropriately selected patients.
• Patient-specific planning: more systematic use of CT reconstruction, three-dimensional anatomy, and imaging-guided decisions about access and cannulation.
• Computer-assisted surgery: image guidance, workflow support, and motion-tracking technologies are under development; autonomous intracardiac surgery is not an established clinical practice.
• Training and implementation: simulation, mentoring, credentialing, registries, and procedure-specific outcome reporting are likely to be as important as new devices.

These are directions of development, not predictions that every technique will become routine. The evidence required for widespread adoption should include durable clinical outcomes, patient-reported recovery, safety during implementation, and cost-effectiveness.

Where do we stand?

Minimally invasive cardiac surgery is no longer a single experimental category. Selected mitral and aortic valve procedures, MIDCAB, and several other limited-access operations are established components of practice in experienced centers. Robotic mitral surgery and multivessel thoracotomy CABG continue to expand, but their incremental benefit over well-executed alternatives is not equally well established.

Three principles should guide the next phase:

1. Preserve the operation. Repair durability, myocardial protection, graft quality, and completeness of treatment take priority over incision size.
2. Select the patient and technique together. Anatomy, perfusion strategy, comorbidity, and team experience determine whether limited access is genuinely advantageous.
3. Measure outcomes that matter. Mortality and stroke remain essential, but functional recovery, repeat intervention, quality of life, and resource use are needed to judge the full value of MICS.

The future of minimally invasive cardiac surgery is not simply smaller incisions. It is reproducible, high-quality cardiac surgery with less access-related harm—and evidence that patients are better off because of it.

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References

1. Chemtob RA, et al. A Conservative Screening Algorithm to Determine Candidacy for Robotic Mitral Valve Surgery. The Journal of Thoracic and Cardiovascular Surgery. 2022;164(4):1080–1087. doi:10.1016/j.jtcvs.2020.12.036.
2. Demianenko V, et al. The TCRAT Technique (Total Coronary Revascularization via Left Anterior Thoracotomy): Renaissance in Minimally Invasive On-Pump Multivessel Coronary Artery Bypass Grafting? Journal of Cardiovascular Development and Disease. 2026;13(1):28. doi:10.3390/jcdd13010028.
3. Demirkıran T, et al. Total Coronary Revascularization via Left Anterior Thoracotomy: Comparison of Early- and Mid-Term Results with Conventional Surgery. Turkish Journal of Thoracic and Cardiovascular Surgery. 2024;32(4):402–411. doi:10.5606/tgkdc.dergisi.2024.26471.
4. Gallingani A, et al. Percutaneous Coronary Intervention or Minimally Invasive Coronary Bypass for Isolated Left Anterior Descending Artery Disease. The American Journal of Cardiology. 2025;249:36–42. doi:10.1016/j.amjcard.2025.04.014.
5. Gong Y, et al. Minimally Invasive vs Conventional Coronary Bypass Surgery for Multivessel Coronary Disease. Annals of Thoracic Surgery Short Reports. 2025;3(2):402–407. doi:10.1016/j.atssr.2024.10.024.
6. Holzhey DM, et al. Learning Minimally Invasive Mitral Valve Surgery: A Cumulative Sum Sequential Probability Analysis of 3895 Operations From a Single High-Volume Center. Circulation. 2013;128(5):483–491. doi:10.1161/CIRCULATIONAHA.112.001402.
7. Kofler M, et al. Endo-Aortic Balloon Occlusion versus Transthoracic Clamping in Minimally Invasive Mitral Valve Surgery. European Journal of Cardio-Thoracic Surgery. 2025;67(9):ezaf258. doi:10.1093/ejcts/ezaf258.
8. Olsthoorn JR, et al. Effect of Minimally Invasive Mitral Valve Surgery Compared to Sternotomy on Short- and Long-Term Outcomes: A Retrospective Multicentre Interventional Cohort Study Based on Netherlands Heart Registration. European Journal of Cardio-Thoracic Surgery. 2022;61(5):1099–1106. doi:10.1093/ejcts/ezab507.
9. Stanislawski R, et al. Long-Term Outcomes of Minimally Invasive Direct Coronary Artery Bypass vs Second Generation Drug Eluting Stent for Management of Isolated Left Anterior Descending Artery Disease. International Journal of Cardiology. 2025;422:132935. doi:10.1016/j.ijcard.2024.132935.
10. Tomšič A, Palmen M. Robotic Mitral Valve Repair Surgery: Where Do We Go from Here? Frontiers in Cardiovascular Medicine. 2023;10:1156495. doi:10.3389/fcvm.2023.1156495.
11. Vo AT, et al. Learning Curve in Minimally Invasive Mitral Valve Surgery: A Single-Center Experience. Journal of Cardiothoracic Surgery. 2019;14(1):213. doi:10.1186/s13019-019-1038-0.

Note: This post synthesizes the accompanying presentation and the listed literature. It is a narrative overview, not a systematic review. The presentation also discusses additional outcome comparisons and emerging technologies not covered directly by all eleven references above; those topics are therefore summarized conservatively rather than assigned unsupported numerical estimates.