Mitral valve repair in the elderly

Mitral valve repair in the elderly

1752 CORRESPONDENCE [1]. Dr Wait raises multiple issues including risk-adjusted mortality, selection bias in the on-pump or off-pump group affecting...

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1752

CORRESPONDENCE

[1]. Dr Wait raises multiple issues including risk-adjusted mortality, selection bias in the on-pump or off-pump group affecting outcomes, and the role of coronary artery anatomical features not factoring into risk assessment models. The implication of the last is that by default, selecting patients with adverse coronary artery anatomy (eg, small vessels, distal disease, and calcium) into the on-pump surgical group may have led to a selection bias against favorable outcomes in the on-pump group. Regarding the first point, the mortality results as reported in the study were observed and not risk adjusted. The National Society of Thoracic Surgeons Logistical Regression Risk Model was indeed used to determine predicted risk in the on-pump (2.3 ⫾ 3.3) and the off-pump (2.7 ⫾ 2.6) groups ( p ⫽ not significant). Mortality, however, was reported as observed mortality only, 2% in the on-pump group and 1% in the off-pump group ( p ⫽ 0.484). The point raised in my discussion was that if risk-adjusted mortality had been reported, as there was a trend toward higher risk and a trend toward a lower observed mortality in the off-pump group, perhaps the mortality difference would have been significant. Without knowing the risk model’s average mortality risk factor for the population studied, however, the reader is unable to make that determination. Selection bias is a known hazard of any outcomes analysis, hence the value of evidence-based medicine and the randomized trial in determining the potential therapeutic benefit of a new therapy. However, valuable information can still be gleaned from analysis of outcomes of large populations with appropriate statistical tools. Shortcomings of the study by Kshettry and associates [1] may include selection bias, surgeon variability, and small sample size. To address these variables, the combination of statistical analysis of outcomes using the model of multivariate logistic regression to determine propensity scores and then computer matching of the study groups on the basis of these scores has been proposed. Although still not perfect, it can further attenuate the role of selection biases in outcomes analysis. Dr Wait’s final point addresses the role of coronary artery anatomy and its potential impact in adversely affecting outcomes in the on-pump group. Although it is tempting to say that vessel size, calcium, and distal disease have the potential to adversely affect results, presumably by contributing to graft loss, I am not aware that this has ever been successfully incorporated into any risk model. Reading Dr Wait’s second reference sheds no further light on this subject for me. Indeed, I believe it was the ambiguities of accurately defining factors such as target vessel size and degree of distal disease that led The Society of Thoracic Surgeons database to abandon these data entry fields after many years of collection. It is true that small, diffusely diseased distal vessels present more of a technical challenge in both on-pump and off-pump operations, but multiple unselected experiences with all patients undergoing beating-heart surgical intervention now exist, thus eliminating any possible selection bias favoring off-pump surgical cohorts. My experience in the year 2000 with 180 consecutive coronary artery bypass grafting operations, 98% of which were performed without cardiopulmonary bypass (the only patients having operation on pump were for a randomized study), included no operative mortality (1.8% in 1999 unselected off-pump surgical procedures) and no return to the operating room for bleeding. Although this experience is still relatively small, it totally removes any selection bias from outcomes analysis and still demonstrates results superior to my previous results with onpump coronary artery bypass grafting. © 2001 by The Society of Thoracic Surgeons Published by Elsevier Science Inc

Ann Thorac Surg 2001;71:1748 –56

Although I think that Dr Wait raises a potentially valid point regarding the role of coronary artery anatomy on the impact of coronary artery bypass grafting outcomes, there is no way of affirming this from any of the published series or statistical models of outcomes of coronary artery bypass grafting. Michael J. Mack, MD Cardiopulmonary Research Science and Technology Institute 8440 Walnut Hill Lane, Suite 705 Dallas, TX 75231 e-mail: [email protected].

Reference 1. Kshettry VR, Flavin TF, Emery RW, Nicoloff DM, Arom KV, Petersen RJ. Does multivessel, off-pump coronary artery bypass reduce postoperative morbidity? Ann Thorac Surg 2000; 69:1725–31.

Mitral Valve Repair in the Elderly To the Editor: I read with interest the report by Grossi and colleagues [1] in which the authors report their results with mitral valve reconstruction in 278 patients operated on between 1980 and 1997. All patients were 70 years old or older (mean age 75.2 years). Isolated mitral valve repair was performed in 77 patients. The survival rate at 5 years was 72% and compared favorably with that in a matched control group from the general population. Freedom from reoperation at 5 years was 92.6% for isolated mitral valve repair and 91.8% for combined procedures. The authors analyzed several studies discussing results of mitral valve replacement in the elderly population, but the only study they referred to that deals with mitral repair is one by Bolling and associates [2] concerning ischemic mitral regurgitation in patients older than 65 years. Therefore, what is remarkable in their report is that Grossi and colleagues made no allusion to previous work from Broussais Hospital by my co-workers and I [3], a study presented at the 64th annual meeting of the American Heart Association in 1991 and later published. In this study, the hospital records of 79 consecutive patients older than 70 years (mean age, 74 years) who underwent mitral valve repair were reviewed. Results were comparable to those reported by Grossi and coauthors. Survival at 5 years was 81% and 97% of patients remained free from reoperation. In the majority of patients, a substantial improvement in New York Heart Association functional class was observed. I congratulate the group from New York University Medical Center on their good study and excellent surgical results. However, I emphasize that their conclusions are identical to ours as reported in 1992 in embracing mitral valve repair as the treatment of choice for mitral regurgitation in elderly patients. Victor Jebara, MD Department of Cardiovascular and Thoracic Surgery Saint-Joseph University Hoˆtel-Dieu de France Rue Adib - Ishak Beirut, Lebanon e-mail: [email protected]. 0003-4975/01/$20.00

Ann Thorac Surg 2001;71:1748 –56

CORRESPONDENCE

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References

References

1. Grossi EA, Zakow PK, Sussman M, et al. Late results of mitral valve reconstruction in the elderly. Ann Thorac Surg 2000;70: 1224– 6. 2. Bolling SF, Deeb GM, Bach DS. Mitral valve reconstruction in elderly, ischemic patients. Chest 1996;109:35– 40. 3. Jebara VA, Dervanian P, Acar C, et al. Mitral valve repair using Carpentier techniques in patients more than 70 years old. Early and late results. Circulation 1992;86(5 Suppl):II53–9.

1. Kunitomo R, Goto H, Utoh J, Kitamura N. Thoracoabdominal aortic aneurysm combined with aortic occlusion. Ann Thorac Surg 2000;69:623–5. 2. Gott VL. Heparinized shunts for thoracic vascular operations. Ann Thorac Surg 1972;14:219–20. 3. Verdant A, Page A, Cossette R, Dontigny L, Page P, Baillot R. Surgery of the descending thoracic aorta: spinal cord protection with the Gott shunt. Ann Thorac Surg 1995;60:1151–2.

Simple Shunting of Thoracoabdominal Aneurysms With Visceral Perfusion To the Editor: We read with interest the case report written by Kunitomo and associates [1] regarding thoracoabdominal aortic aneurysm repair using cardiopulmonary bypass (CPB) with selective perfusion of the viscera. Our method for the repair of isolated thoracic and thoracoabdominal aneurysms parallels that described by the authors, however, since April 1999, we have been doing it without the use of CPB. We incorporate a variant of the Gott shunt [2], whose reliability and safety for distal perfusion has been shown [3]. We have been able to cannulate the descending aorta or distal arch as an inflow and cannulate the distal aorta or iliac arteries as well as up to four visceral organs requiring perfusion (left and right kidneys, celiac axis, and superior mesenteric artery). In this manner, we perfuse the lower extremities and viscera and reduce the hemodynamic load on the heart during aortic crossclamp. Intermittant occlusion of the shunt distal to the visceral bed can be performed as required to reduce the cardiovascular affects of bleeding and thereby increase proximal blood pressure so that the coronary, cerebral, and visceral perfusion pressures are maintained to a greater extent. To shunt arterial blood around the aneurysm we use standard 8-mm Sarns (Terumo, Ann Arbor, MI) aortic cannulas interconnected with 3⁄8 ⫻ 3⁄8-inch straight connectors (Baxter, Irvine, CA). A “T” to a multiple perfusion set or “octopus” (Medtronic, Grand Rapids, MI) attached to straight coronary cannuli with balloon tips (4 to 8 mm) (Polystan A/S, Walgerholm, Denmark) allows for direct perfusion of the viscera. Distally, we have always perfused within the thoracoabdominal cavity, and the femoral vessels can be cannulated separately if necessary. Heparinization of only 5,000 to 10,000 units was used in all cases. We believe that this system is very easy to use, using readily available instruments without the need for specialized technicians. It can thus be utilized in centers that do not have cardiopulmonary bypass capabilities. The lungs oxygenate the blood and the circuit can be used to diminish the cardiovascular effects of cross-clamping and bleeding during the operation while maintaining visceral perfusion. We feel that this technique affords an easier and alternative approach than that taken by the authors for thoracic and thoraco-abdominal aneurysm repairs when visceral and distal perfusion are required. Salvatore Privitera, MSc Robert J. Cusimano, MD, MSc Division of Cardiovascular Surgery The Toronto Hospital 200 Elizabeth St Toronto, ON, Canada, M5G 2C4 e-mail: [email protected]. © 2001 by The Society of Thoracic Surgeons Published by Elsevier Science Inc

Reply To the Editor: We would like to thank Mr Privitera and Dr Cusimano for their comment on the blood supply of the abdominal viscera and lower extremities during aortic clamping in our case [1]. We agree that the Gott shunt [2] is effective for distal perfusion with a low dose of heparin and obviates the need for cardiopulmonary bypass as the authors described. However, we suggest that the shunt flow may become variable by opening or clamping the shunt, or by the use of cardiovascular agents. In addition, we can not control proximal blood pressure to maintain coronary and cerebral blood perfusion only by the Gott shunt if massive bleeding occurs. We believe that the use of cardiopulmonary bypass and selective distal perfusion was much safer than the Gott shunt in our case, because the patient also had a distal aortic aneurysm proximal to the clamping site. We also believe that the Gott shunt is not always applicable for all thoracic and thoracoabdominal aneurysms. The perfusion support system should be selected case by case. Ryuji Kunitomo, MD First Department of Surgery Kumamoto University School of Medicine 1-1-1 Honjo Kumamoto 860-8556, Japan e-mail: [email protected].

References 1. Kunitomo R, Goto H, Utoh J, Kitamura N. Thoracoabdominal aortic aneurysm combined with aortic occlusion. Ann Thorac Surg 2000;69:623–5. 2. Gott VL. Heparinized shunts for thoracic vascular operations. Ann Thorac Surg 1972;14:219–20.

Successful Recovery of Allograft Failure With Biventricular Support To the Editor: We read with interest the article by Albes and colleagues [1]. This excellent article points out that mechanical ventricular assistance is recommended as a therapeutic option for primary cardiac allograft failure, although only a limited number of successful cases have been reported. We previously reported a case of a patient with a primary graft failure, who recovered with pneumatic biventricular assistance [2]. Our patient was a 41-year-old man who underwent orthotopic heart transplantation. Intraoperative acute allograft failure occurred and required immediate placement of a pneumatic 0003-4975/01/$20.00