Eur J Cardiothorac Surg 2002;22:206-210
© 2002 Elsevier Science NL
Long term follow-up of surgical treatment of hypertrophic obstructive cardiomyopathy (HOCM): the role of concomitant cardiac procedures
Kazutomo Minami*,
Dietmar Boethig,
Hajo Woltersdorf,
Dirk Seifert,
Reiner Körfer
Department of Thoracic and Cardiovascular Surgery, Heart Center NRW, University of Bochum, Georgstr. 11, 325 45 Bad Oeynhausen, Germany
Received 25 October 2001;
received in revised form 5 April 2002;
accepted 17 April 2002.
* Corresponding author. Tel.: +49-5731-97-1235; fax: +49-5731-97-1300
e-mail: kminami{at}hdz-nrw.de
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Abstract
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Background: In patients who underwent transaortic myectomy for hypertrophic obstructive cardiomyopathy (HOCM), we evaluated the role of concomitant procedures for short and long term outcome. Methods: From 1985 to 2000, in 125 patients a myectomy according to Morrow was performed. A total of 75 patients (group I) had isolated HOCM: 37 females, 38 males, mean age 52.1 years (14–79). The 50 patients of group II – 22 females, 28 males, mean age 62.4 years (36–77)-had concomitant procedures: coronary artery bypass grafting (36), mitral valve repair (15), DeVega-plasty (1), ventricular septal infarction-closure (1). Follow-up data of a total of 680.9 years (mean 5.4) were analyzed. Results: Postoperatively, left ventricular outflow tract gradients at rest and after ventricular premature beats were significantly reduced (P<0.001). Mean performance of survivors (112/125=89.6%) improved significantly (P<0.001). Perioperative complication rates: 10.7/12.0% (groups I/II), early lethality: 1.3/2.0%. Survival rates after 5/10 years were 93±3/87±6 and 80±7/80±7% for groups I and II, respectively. Conclusion: Long term results after surgical treatment of HOCM are convincing also if concomitant procedures are performed.
Key Words: Hypertrophic obstructive cardiomyopathy • Mitral insufficiency • Concomitant procedures
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1. Introduction
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Transaortic myectomy according to Morrow is an established operative procedure in patients with isolated hypertrophic obstructive cardiomyopathy (HOCM) [1]. Current early mortality rates for myectomy alone vary from 1 to 5% [2–5]. Reported 10 year survival rates range from 76 to 88% [6–9]. Few studies deal with the impact of additional cardiac operative procedures on short and long term survival. The present study aims to determine whether concomitant cardiac procedures influence safety and late results of transaortic myectomy. We analyzed follow up results of a group of 125 consecutive patients operated between 1985 and June 2000.
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2. Material and methods
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Among the 45 545 patients who underwent cardiac surgery with extracorporal circulation in the Heart Center NRW Bad Oeynhausen between November 1985 and June 2000, 125 patients (0.27%) were operated for HOCM. Diagnosis was mainly found by echocardiography and always confirmed by cardiac angiography. All patients were operated by the transaortic approach according to Morrow. Patients were divided into two groups: group I consisted of 75 patients with isolated HOCM, 37 women and 38 men between 14 and 79 years, mean age 53.1 years. Group II included 50 patients with HOCM and additional heart diseases, 22 women and 28 men, aged between 36 and 77 years, mean 62.4 years (Table 1). Besides the Morrow procedure, 36 patients had coronary artery bypass grafting, 15 mitral valve repair (MVR) for valve related mitral regurgitation, one DeVega-plasty. Prior to correction, more than 96% of the patients in both groups were in functional class III–IV according to New York Heart Association (NYHA). All patients underwent echocardiographic examination and cardiac catheterization. A grades II or III mitral regurgitation (MR) considered secondary was present in 28 group I and nine group II patients. A total of 15 group II patients had MR considered valve related. For further echo results and group description parameters see Table 1. The preoperative lethality risk as determined by Euroscore [10] is 1.9±1.7% in the HOCM alone group and 4.0±2.5% in the group with concomitant procedures. Although the difference is statistically significant (P=0.03), these rates are virtually equal in both groups, since the average 2 of additional points (2% higher risk for early death) in the group with concomitant procedures results from the fact itself that concomitant procedures were performed. A hemodynamically effective aortic valve stenosis was excluded in all patients of both groups. The follow-up data collection included patient interviews by questionnaire regarding NYHA classification grades. Table 4 shows the echocardiographic parameters that were determined preoperatively and actually. A total of 90% of the echo data were obtained in our institution. Left ventricular systolic gradients were measured preoperatively in the catheter lab and intraopertively prior to correction, both at rest and after induced ventricular premature beats (VPBs). Mitral valve incompetence was considered secondary and subsequently not treated with valve replacement when neither evident structural MV damage nor persisting MR after myectomy in the intraoperative TEE was seen.
Two group I patients and one group II patient were lost for follow up; thus, follow up is 97%. Total follow up time is 506.1 (6.7±4.1) patient years in group I and 180.4 (3.6±3.2) patient years in group II.
Statistics: SPSS 10.0 was used for all calculations. Mean values are given with standard deviation. Patient group characteristics and operation times were compared by unifactorial analysis of variance (ANOVA), value changes from pre- to postoperative were compared using the Wilcoxon test for paired samples.
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3. Results
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Mean times for ischemia, extracorporal circulation (ECC), reperfusion and total operation were significantly longer in group II than in group I (Table 2). Intraoperatively measured LVOTGs were significantly reduced both at rest and after VPBs. (Fig. 1)
. Nine patients of group I had early postoperative complications (Table 3), among them one lethal multi organ failure. Early mortality was 1.3%.
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Fig. 1. Intraoperatively measured LVOTGs show significant reduction after myectomy at rest and after VPBs.
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Six group II patients had early postoperative complications, including one lethal mesenterical infarction and one paravalvular leakage (Table 3). Group II early lethality rate was 2%.
Overall early letality was 1.6%.
Secondary mitral insufficiency was decreased to non-relevant grades in 36 of 37 patients without intervention on the mitral valves. One group I patient had a persisting hemodynamically relevant mitral regurgitation treated successfully by later mitral valve replacement.
Late results: Overall survival after 5 and 10 years was 90.1±3.1 and 82.7%, respectively. In both groups, mean performance (NYHA grade) improved significantly (Fig. 2)
. Echocardiography showed statistically significant enlargement of left ventricular enddiastolic diameter (LVEDD) and left ventricular endsystolic diameter (LVESD) and significant reduction of enddiastolic diameter of intraventricular septum (IVS-EDD), enddiastolic diameter of posterior wall (PW-EDD) and LA diameter (Table 4). Two group I patients with HOCM recurrences after 7 and 10 years were successfully treated by percutaneous transluminal coronary septal myocardial ablation. Late lethality: in group I, one patient died of LOS, four due to non-cardiac reasons. In group II, two patients died due to myocardial infarction, one after endocarditis, one of LOS, and two of non-cardiac causes. The overall 10 year actuarial survival rate was 85.6% in group I and 80.3% in group II (Fig. 3)
. Log rank test comparison shows no statistically significant difference (P=0.06).
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Fig. 2. Clinical symptoms according to New York Heart Association (NYHA) prior to and after correction.
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4. Discussion
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The mortality rate of hypertrophic obstructive cardiomyopathy under medical treatment alone (patients in any state) is about 15% at 5 years and 25% at 10 years, increasing annually by 3–5% [11–13].
Transaortic myectomy according to Morrow is the surgical treatment of choice in patients with HOCM. In the present study we found a low early mortality rate (1.3%) in patients with isolated HOCM as well as in patients with concomitant cardiac procedures (2.0%). The low early mortality rate in the HOCM alone group is the measuring mark for alternative therapeutical options [14]. As shown in the studies that stratify their results by the need for concomitant procedures (Table 5, bottom), early death rates in the HOCM alone subgroup generally tend to be lower.
In our patient series, diagnosis of secondary mitral insufficiency was correct in 97%; only one out of 37 patients needed a redo operation for mitral valve replacement. Similar reliability has been described previously [20]. The severity of secondary mitral insufficiency correlates with the LVOTG [21] and is usually treated sufficiently by myectomy [22,23].
In this study, patients with concomitant procedures did not survive significantly shorter than those with myectomy alone. The lack of statistical significance despite diverging Kaplan–Meier curves (Fig. 3) may be due to the relatively small number of patients at long term risk. On the other hand, patients with concomitant procedures had an higher age average, so that shorter long term survival could be expected. Results in the literature concerning concomitant procedures as a risk factor for premature death remain controversial: Schoenbeck [16] found additional procedures to rise the risk of premature death threefold, Mohr [18] identified them as an univariate risk factor. Following Schoenbeck's analysis, age is no independent risk factor-opposite results emerge from other studies (Mohr [18], Robbins [19]). The number of individual and procedural factors that influence survival is great, and generally only a small fraction of patients has died at the end of the study. We might just have to admit that patient numbers around 120 are hardly sufficient to accurately detect each real risk factor. In larger patient series as presented by Schulte, the long study interval makes outcomes hard to compare – due to the development of the operating theatre equipment. The only way to collect sufficient data within a reasonable time period seems to be ‘as often’ a multicenter study. However: in our HOCM patient population, concomitant procedures were no univariate risk factor concerning long term survival.
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5. Conclusion
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Morrow procedure for HOCM shows very satisfactory early and long term results: early mortality is 1.6%, 10 year survival 83%. Iatrogenic septal defects are rare (1.6%) and cause no sequelae if corrected intraoperatively. Additional concomitant procedures increase complication and mortality rates only slightly. Mitral valve incompetence repair can be limited to patients with structural valve damage; diagnosed secondary insufficiency is cured in 97% by correcting the underlying LVOT obstruction. Patients with or without concomitant procedures have considerable benefits of the operative therapy in terms of improved life expectancy and performance status.
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Footnotes
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Presented at the joint 15th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 9th Annual Meeting of the European Society of Thoracic Surgeons, Lisbon, Portugal, September 16–19, 2001.
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Appendix A. Conference discussion
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Dr D. Wheatley (Glasgow, Scotland): I have one general comment about this paper. I think it is extremely important. And it is important because of the advent of septal artery embolization as an alternative therapy for this, and unless as surgeons we can produce the data on the surgical intervention, we are going to have great difficulty in putting this into the right context, and I wonder if you could very briefly comment on your center's view of management of hypertrophic obstructive cardiomyopathy in the light of septal embolization?
Dr Minami: I didn't get quite your question. I am sorry for that.
Dr Wheatley: Are you still advocating this technique, the Morrow technique, for the treatment of hypertrophic obstructive cardiomyopathy, or are your cardiologists undertaking septal ablation non-invasively or minimally invasively?
Dr Minami: Oh, yes, the new technique was introduced almost 5 years ago in our hospital, and some patients are coming directly to the cardiac department. So that nowadays if the patient has isolated HOCM, then they will be treated by an alcohol injection of the septum. But if they have a secondary concomitant disease, they are coming to us. That is now the policy of our cardiac department.
Dr Wheatley: This is terribly important data for the audience, for all of us to know, because this whole comparison between medical interventions and surgical is getting to be of increasing importance.
Dr Minami: That's right.
Dr J. Tsai (Pingtung, Taiwan): Would you kindly tell us what is the incidence of infective endocarditis in your hypertrophic obstructive cardiomyopathy in 120 cases? Because in the experience, infective endocarditis is quite a number, but in your 120 cases, no infective endocarditis at all. I would like to ask you, what is your incidence?
Dr Minami: Infective endocarditis is quite a different disease. I reported about obstructive cardiomyopathy, hypertrophic obstructive cardiomyopathy, or IHSSS. That's quite different.
Dr Wheatley: But did any of your patients have infective endocarditis?
Dr Tsai: I just asked HOCM in your series about the incidence, percentage.
Dr Minami: Okay. It is a very difficult question, but out of 50 000 open heart cases which are done in our hospital, we have just only 125.
Dr Tsai: I would like to ask just straight to the question, hypertrophic HOCM, because our experience is about 10–12%. How your big series, I do appreciate your report, it is a big series, but according to the textbook, it is about 10–20%, but your report, because your complication is about 1% of mitral valve regurgitation, so I would like to ask, would you kindly recheck again what is your incidence of infective endocarditis in your big series?
Dr Minami: Okay, I have to check that out.
Dr M. Turina (Zurich, Switzerland): Maybe I can answer you. We have a series of 100 patients with the same disease and not a single case of infective endocarditis. So I am surprised at the question.
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References
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Abstract
1. Introduction
