The Results of Valve Replacement for Mitral Valve Prolapse

The Results of Valve Replacement for Mitral Valve Prolapse

The Results of Valve Replacement for ~ t r Valve d Prolapsi William L. Old, 111, M.D., John W. Hammon, Jr., M.D., Clarke W. Henry, M.D., Richard L. Pr...

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The Results of Valve Replacement for ~ t r Valve d Prolapsi William L. Old, 111, M.D., John W. Hammon, Jr., M.D., Clarke W. Henry, M.D., Richard L. Prager, M.D., and Harvey W. Bender, Jr., M.D. ABSTRACT Between January, 1975, and December, 1982, 33 patients underwent mitral valve replacement for mitral valve prolapse secondary to myxomatous degeneration. The majority were in the seventh decade of life (median age, 62 years), and all were seen with symptoms of mitral regurgitation. Echocardiography was more accurate in making the diagnosis of mitral valve prolapse more often (75%)than angiography (66%).Thirty-eight percent of the patients who underwent cineangiography had concomitant coronary artery disease and had coronary artery bypass grafting as well as mitral valve replacement. There was 1 operative death, an operative mortality of 3%.There were 6 late deaths, a late mortality of 18%.Of the 26 long-term survivors, 23 (88%)were in New York Heart Association Functional Class I and 3 (12%)were in Class 11. The average length of follow-up was 33.25 months, and the 5-year actuarial survival was 76%.There was only one incident of thromboembolism (3%1. Short-term and long-term survival were not related to the severity of mitral regurgitation but to the status of the left ventricle and the overall condition of the patient. These data suggest that older patients with severe mitral regurgitation secondary to mitral valve prolapse can undergo valve replacement with low operative mortality and gratifying long-term results. The syndrome of mitral valve prolapse was defined by Barlow and colleagues [l]in the mid-1960s to be the association of late systolic murmurs and nonejection clicks with a pathological condition of the mitral valve, specifically, with prolapse of a billowing posterior leaflet. In a relatively small percentage of patients with this condition, the prolapsing valve may develop severe mitral regurgitation requiring surgical correction (often called floppy valve syndrome [2]). In this article, we have attempted to identify patient characteristics and indications for operation and to compare the results of operation with those from other reports.

Material and Method The Vanderbilt University experience was reviewed for the 8-year period from January, 1975, through Decem-

From the Department of Cardiac and Thoracic Surgety, Vanderbdt University Medical Center, Nashville, TN. Presented at the Thirty-first Annual Meeting of the Southern Thoracic Surgical Association, Hilton Head Island, SC, Nov 1-3, 1984. Address reprint requests to Dr. Hammon, 338 Medical A r t s Bldg, 1211 21st Ave S, Nashville, TN 37212.

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ber, 1982. Out of approximately 300 mitral valve replacements done during this time, 33 were performed for regurgitation from a myxomatous mitral valve. The patients were selected on the basis of operative and gross anatomical descriptions of a prolapsing valve having the characteristic features that will be reviewed later. Operations were performed through a median sternotomy incision in all patients, and mitral valve replacement was carried out through a left atriotomy just below the right interatrial groove. Interrupted, pledgeted horizontal mattress sutures of 2-0 braided Dacron, placed from the left atrial surface of the mitral annulus and through the sewing ring of the valve, were used in every patient. Aortic cross-clamping was employed during the intracardiac portion of the procedure, and myocardial .protection was offered by cold, hyperkalemic (20 mEq/L) cardioplegic solution injected into the aortic root. Also, topical hypothermic solution was intermittently placed on the endocardia1 surface of the left ventricle. Patients were followed by personal visits or contact with the referring physician. In addition, all patients were contacted to assess their functional state. The results of these examinations were tabulated, and actuarial survival was calculated.

Results There were 21 men (64%)and 12 women (36%).The age distribution showed a peak incidence in the seventh decade of life. The ages ranged from 18 to 80 years with an average age of 59.1 years and a median age of 62 years (Fig 1). Thirty-two patients (97%)had symptoms of heart failure, decreased exercise tolerance, fatigue, dyspnea, and orthopnea. Nine patients (27%) complained of palpitations. Four patients (12%)complained of chest pain, and 3 of them subsequently were shown to have concomitant coronary artery disease. Twenty-seven patients (82%) were in New York Heart Association Functional Class 111, 5 (15%)were in Class 11, and 1 (3%)was in Class I. This last patient had severe aortic stenosis, which presented with dramatic repetitive syncopal attacks, and mitral regurgitation. Twenty-nine patients (88%) had a history of known heart murmurs for an average of 18.6 years before the operative procedure. Two patients (6%) had a previously documented episode of endocarditis. Seven patients (21%) were suspected of having ruptured chordae tendineae preoperatively on the basis of a history of abrupt onset of symptoms unrelated to arrhythmias, and the diagnosis was confirmed in all of them at operation. Ten other patients (30%)who were seen with a history of progres-

32 The Annals of Thoracic Surgery Vol 40 No 1 July 1985

Comparisons of Preoperative Hemodynamic Data

Variable

-

PAP(mmHg) PCWP (mm Hg) vwave(mm Hg) CO (Wmin) CI (Wmin/m2) LVEDP (mm Hg)

IU

n

10 2.0 30 40 30 60 70 80

AGE Fig I . Age distribution of the patients.

sive mitral regurgitation also had ruptured chordae. Thus, of 17 patients with ruptured chordae, 41% were seen with the abrupt onset of severe mitral regurgitation. No patients in this series had characteristicsof Marfan’s syndrome. Twenty-nine patients (88%)were on a regimen of digoxin at the time of admission for valve replacement. Six (18%)were taking quinidine; 3 (9%), procainamide; and 4 (12%), propranolol hydrochloride. Twenty patients (61%)were in atrial fibrillation, and 25 (76%)were noted to have nonspecific ST-T segment changes on the electrocardiogram preoperatively. Only 1 had Q waves indicating a previous anterior myocardial infarct. Thirteen patients (39%) met electrocardiographic criteria for left ventricular hypertrophy. A history of ventricular arrhythmias was noted in 10 patients (30%). One patient had several documented episodes of ventricular tachycardia with one episode of ventricular fibrillation two weeks prior to operation. She was treated with procainamide. Postoperatively, she was discharged on a regimen of digoxin only, and had no further difficulty with ventricular arrhythmias after valve replacement. Thirty-two preoperative chest radiographs (97%)demonstrated increased heart size. Twenty-eight patients (85%) had echocardiography as part of the diagnostic workup. Twenty-one (75%) of these 28 patients were diagnosed as having mitral valve prolapse. Six of the remaining 7 were noted to have left atrial enlargement. Cardiac catheterization was performed on all patients. Hemodynamic data were compatible with severe mitral regurgitation (Table) and are consistent with findings in other surgical series [3, 41. Twenty-one (66%)of thirtytwo cineangiograms were interpreted as demonstrating severe mitral regurgitation. Four patients were found to have angiographically poor resting ventricular function. Twelve (38%)of the thirty-two cineangiograms revealed coronary artery disease. Seven of these patients had single-vessel coronary artery disease, 3 had triplevessel coronary disease, and 2 had double-vessel coronary disease. Single grafts were placed in all 7 patients with single-vessel disease, and two grafts were placed in

-

Yacoub et al [4]

Salomon et al (31

31 18-20 33-36

34 22.6

...

...

... .. .

40

2.1 15

Old et al [this report] Average

Range

35.9 21.1 38.3 3.82 2.28 16.6

16-82.5 6-35 12-58 2.0-5.5 1.4-3.5 9-23

PAP = mean pulmonary artery pressure; PCWP = pulmonary capillary wedge pressure; CO = cardiac output; CI = cardiac index; LVEDP = left ventricular end-diastolic pressure.

each of the 2 patients with double-vessel disease. Three grafts were placed in 2 patients with triple-vessel disease, and the third patient received one graft. All of the patients in this series were operated on for severe mitral regurgitation. The operative description noted prolapse of the anterior leaflet in 4 patients (12%), the posterior leaflet in 2 (6%), and both leaflets in 18 (55%).For the other 9 patients (27%),the operative notes failed to specify which leaflet was prolapsed. As already discussed, ruptured chordae were found in 17 patients (52%).The pathologist confirmed the gross appearance of myxomatous mitral valve in all 33 patients. Complications of operation included the following: reexploration for bleeding in 1 patient (3%), postoperative inotropic support for forty-eight hours or longer in 9 patients (27%),prolonged dysfunction of the central nervous system in 2 patients (6%), sternal dehiscence in 1 patient (3%),and postoperative cardiac arrhythmias requiring multiple antiarrhythmic medications in 4 patients (12%). Four patients had Bjork-Shiley valves inserted (three 31 mm and one 33 mm), all since 1980. Three of these patients are doing well. Since 1975, twenty-five Hancock porcine xenograft prostheses have been inserted (29 to 35 mm) and four CarpentierEdwards prostheses (29 to 35 mm). There was 1 operative death, which was caused by mediastinal sepsis in a young patient requiring mitral and tricuspid valve replacement (3% operative mortality). There were 6 late deaths (18%late mortality). Three patients died of ventricular arrhythmias at 5, 9, and 10 months postoperatively. Two of these patients had both left ventricular dysfunction and coronary artery disease. They underwent single or triple coronary artery bypass grafting along with the valve replacement. Their postoperative courses were marked by bouts of congestive heart failure. The third patient had ventricular arrhythmias, including ventricular tachycardia, that were difficult to control. They occurred both before and after operation. One patient with poor ventricular function died six weeks postoperatively of severe congestive heart failure and chronic obstructive pulmonary disease.

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Old et al: Valve Replacement for Mitral Valve Prolapse

Thus, of the 4 patients with angiographically poor ventricular function diagnosed preoperatively, 3 were dead within 10 months. One patient died 6 months postoperatively of metastatic renal cell carcinoma, diagnosed only 2 months earlier. Another patient died 39 months after operation of the effects of two cerebrovascular accidents. This patient was a 67-year-old woman who underwent operation in 1978. A Hancock prosthesis was inserted, and she was discharged on a regimen of aspirin and Persantine (dipyridamole). No other known complications from thromboembolism have occurred in this series. All patients but 6 were discharged on a regimen of Coumadin (crystalline warfarin sodium) anticoagulation. These 6 all had Hancock porcine prostheses implanted, and 3 of them were in normal sinus rhythm at the time of discharge. However, it was noted on follow-up that the anticoagulation regimen had been discontinued in 13 of 20 patients with porcine xenograft valves and that those patients were doing well. Average length of follow-up of the 26 patients still alive is almost 3 years (33.25 months). All of them were interviewed recently. Twenty-three (88% of survivors) feel well and deny any limitation on their daily activities (Class I). The 3 others (12% of survivors) have dyspnea on moderate exertion but are asymptomatic at rest (Class 11). No reoperations were done in this series of patients. The overall mortality was 21%, and the 5-year actuarial survival is 76% (Fig 2).

Comment The underlying pathological feature of mitral valve prolapse is a myxomatous change in the valve tissue, marked histologically by an increase in ground substance and distortion of the normal valve architecture. Fig 2 . Postoperative actuarial survival

4

8

12

16

20

24

Either or both leaflets may be involved. Gross anatomical features include redundant, voluminous, and sometimes scalloped leaflets, often with a thick opposing edge; dilatation of the mitral valve annulus; and long, thin, sometimes ruptured chordae. Most series now exclude from this syndrome patients with obvious rheumatic valve disease and the papillary muscle dysfunction of ischemic heart disease. Barlow and associates [l] noted that the natural history of this syndrome is not always benign. Complications include sudden death, arrhythmias, chest pain, endocarditis, ruptured chordae, and progression to severe mitral regurgitation [l].From several reports on the natural history of mitral valve prolapse, it appears that one of these complications will develop in approximately 14% of patients [5, 61. Such complications, with the exception of sudden death, have been successfully treated surgically, and mitral regurgitation is by far the most common indication for operation. The characteristics of the patients in this series are similar to those in other reports of surgically treated mitral valve prolapse [2-41. The male preponderance is a common feature of other surgical series despite the fact that women constitute 60 to 70% of the patients with Barlow’s syndrome. Why men have a predisposition for severe mitral regurgitation is not known. The diagnosis of a myxomatous prolapsing valve as the cause of rnitral insufficiency was made preoperatively more often by echocardiography (75%) than by angiography (66%). The known sensitivity of echocardiography for diagnosing mitral valve prolapse is 80% and was 81% in a 1981 surgical series [4].Angiography was formerly the “gold standard” for diagnosis of the mitral valve prolapse syndrome. Now we realize that it is somewhat nonspecific, since the angiographic picture of mitral valve prolapse can occur in rheumatic heart disease and ischemic heart disease. In this series, a relatively high percentage of patients

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TIME POST OP (MONTHS)

32

36

40

34 The Annals of Thoracic Surgery Vol 40 No 1 July 1985

had concomitant coronary artery disease (38%).Yacoub and co-workers [4] reported that 24% of their patients had coronary artery disease, and Salomon and associates [3] noted coronary artery disease in 18%of patients in whom coronary arteriography was performed. The association between mitral valve prolapse and coronary artery disease has been a subject of much discussion. Confusion seems to arise from the angiographic picture of mitral valve prolapse in some patients with papillary muscle dysfunction secondary to ischemic heart disease. A prolapsing valve leaflet may be an intermediate step before full-blown mitral regurgitation in patients with ischemic papillary muscle disease. These patients do not, however, have the echocardiographic characteristics of prolapse, probably because the leaflets are not redundant or voluminous. Also, at the time of operation the leaflets appear normal rather than myxomatous [7]. Given the male preponderance and a more elderly age group, concomitant coronary artery disease will not be uncommon in these patients. In addition, of 4 patients in this series with angiographically documented poor left ventricular function, 3 had died within 10 months. This suggests that operative intervention be considered before severe left ventricular decompensation occurs. In 1976, Salomon and colleagues [3]presented the results of mitral valve replacement with Starr-Edwards valves in 66 patients with floppy valve syndrome. They reported a 6% operative mortality, a 32% late death rate, and a 5-year survival of 50% (average follow-up, 3.5 years). They noted that postoperative attrition correlated with advanced preoperative functional disability and left ventricular failure. There were twelve episodes of thromboembolism (18%)among the 66 patients. In 1981, Yacoub and associates [4] reported the results of valve replacement done prior to 1975 in 46 patients who received stented, fresh, antibiotic-sterilized homografts for prolapsing mitral valve. The operative mortality was 7% and 5-year survival, 62%. Five patients had prosthetic valve failure. No embolic episodes were noted. Seventy percent of the patients were in Class I or I1 postoperatively. The authors contrasted these results with those in 86 patients who had mitral valve repair after 1975. In this group, operative mortality was only 3% and actuarial 5-year survival, an impressive 90%. Systolic murmurs were noted postoperatively in 50% of these patients, but only 3% of the total group required reoperation, and 94% were considered to be in Class I or I1 postoperatively. There was a 2% incidence of thromboembolism. In 1978, Carpentier and co-workers [8] reported a series of 213 patients treated for mitral valve prolapse between 1969 and 1977 with mitral valve repair. Fortynine of 151 patients with identified causes were thought to have myxomatous degeneration. Operative mortality was 4%; the rate of reoperation was 3%; and the late death rate was a mere 3% with an average follow-up of 4.5 years. Of 93 patients with long-term follow-up (average, 5.1 years), 79 were in Class I, 8 in Class 11, and 6 in

Class 111. Thirty-nine (42%) of these 93 patients had minimal to severe systolic regurgitation murmurs. Only 1 patient had an episode of thromboembolism (0.4%). However, the average age for the overall group equaled only 42 years with a mean age of 52 years for the 49 patients with myxomatous disease. The early results for prosthetic valve replacement (before 1975) are hardly comparable with more recent results (after 1975) for either valve replacement or repair. Operative mortality is lower because of improved myocardial protection and the trend toward operating earlier in the course of the disease. The present prosthetic valves may also be better. Mitral valve repair as advocated by Yacoub and associates [4], Carpentier and colleagues (81, and others is certainly an exciting area of development but appears to be better suited for use in younger patients. The results of repair appear to be good despite a low incidence of continued murmur, symptoms, and need for reoperation. The incidence of thromboembolism is especially low. At this point, however, it is questionable whether a modern series of valve replacements versus a modern series of valve repairs, matched for age and ventricular function, would show significant differences in operative mortality, need for reoperation, postoperative functional class, 5-year survival, or rate of postoperative thromboembolic events (porcine xenografts). In summary, this series demonstrates good results for the treatment of mitral insufficiency secondary to mitral valve prolapse with mitral valve replacement in a group of patients, the majority of whom were older and had a high incidence of concomitant coronary artery disease. We believe that mitral valve replacement is still acceptable and has some advantages in the older patient. Operative mortality is low, and there is less chance for residual mitral regurgitation necessitating early reoperation.

References 1. Barlow JB, Bosman CK, Pocock WA, Marchand P: Late sys-

2. 3.

4. 5. 6. 7. 8.

tolic murmurs and non-ejection systolic clicks. Br Heart J 30:203, 1968 Cooley DA, Gerami S, Hallman G, et al: Mitral insufficiency due to myxomatous transformation: "floppy valve syndrome." J Cardiovasc Surg (Torino) 13:146, 1972 Salomon NW, Stinson EB, Griepp RB, Shumway NE: Surgical treatment of degenerative mitral regurgitation. Am J Cardiol 38:463, 1976 Yacoub M, Halim M, Radley-Smith R, et al: Surgical treatment of mitral regurgitation caused by floppy valves: repair vs. replacement. Circulation 64:Suppl 2210, 1981 Allen H, Harris A, Leatham A: Significance and prognosis of isolated late systolic murmurs: a 9- to 22-year follow-up. Br Heart J 36525, 1974 Mills P, Rose J, Hallingsworth J, et al: Long-term prognosis of mitral valve prolapse. N Engl J Med 29713, 1977 JeresatyRh4: Mitral Valve Prolapse. New York, Raven, 1979, P N Carpentier A, Relland J, Deloche A, et al: Conservativemanagement of the prolapsed mitral valve. Ann Thorac Surg 26294, 1978