Myocardial revascularisation in patients with severe left ventricular dysfunction. Early and midterm results. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub

AIMS
This retrospective study evaluates early and midterm results in patients with severe left ventricular dysfunction.


TECHNIQUE
Ninety-seven consecutive patients with coronary artery disease and ejection fraction of left ventricle (LVEF) less or equal to 25 % underwent elective coronary artery bypass graft procedure between September 1998 and December 2001. Mean age at operation was 66 (47-86) years. The main symptoms were angina class III-IV Canadian Cardiovascular Society (CCS) in 78 patients (80 %) and dyspnoea class III-IV New York Heart Association (NYHA) in 43 patients (44 %). The major indications for surgery were severe angina, dyspnoea in 90 patients (93 %). Cardiac index (CI), echocardiography (ECHO), planimetry, end-diastolic pressure of left ventricle (LVEDP), end-diastolic diameter of left ventricle (LVEDd) were used to access left ventricular function preoperatively. ECHO was also used to access left ventricular function postoperatively.


RESULTS
Early postoperative (30 days) mortality was 4.1 %. Complications had 25 patients (26 %) postoperatively. Two years survival was 95.7 %. Class III-IV CCS and/or NYHA had 17 patients (17.5 %) two years after surgery. LVEF (assessed by ECHO) improved from 23.1 % preoperatively to 36.0 % postoperatively (p < 0.05).


CONCLUSION
The study showed that elective myocardial revascularisation in patients with severe left ventricular dysfunction and signs of myocardial viability is not necessarily associated with high operative mortality. It can be performed safely with respectable midterm survival in concordance with left ventricular function improvement, symptom relief and quality of life improvement.


INTRODUCTION
The results of the medical treatment of patients with coronary artery disease (CAD) and severe left ventricular (LV) dysfunction are poor.However, as many earlier and current studies demonstrate coronary artery bypass graft (CABG) procedure have improved long term survival in patients with impaired ventricular function [1][2][3][4][5][6] over the last fi fteen years.The benefi t is most obvious in patients with severe LV dysfunction with ejection fraction (EF) less then 35 % 1 and signs of myocardial viability.The amount of viable myocardium dictates the degree of improvement in left ventricular function after revascularization 2 .Left ventricular function is an important predictor of early postoperative and late morbidity and mortality 4 .Despite improvement in surgical techniques, myocardial protection and postoperative care, the surgical risk remains high [3][4][5]9 and the procedure is still a major surgical challenge. Thee are however few options for alternative treatment.Transmyocardial laser revascularisation and dynamic cardiomyoplasty are limited in use and in indications.Heart transplantation is a terminal one considering the impossibility of revascularisation and its dependence on donor heart availability as well.
This retrospective study evaluates early postoperative (30-day after surgery) and midterm (1 year after surgery) results in 97 consecutive patients who underwent elective CABG for isolated ischemic heart disease with left ventricular EF 25 % and lower.Early postoperative mortality, complications, clinical status diff erence were analyzed as early postoperative results (30-day after surgery), followed by analysis of midterm results fi gured in as 1-year mortality, EF diff erence and clinical status diff erence.

MATERIALS AND METHODS
Between September 1998 and December 2001, 97 consecutive patients whose preoperative EF (by planimetry) was less than or equal to 25 % underwent elective CABG.Patients undergoing combined procedures as CABG with valvular surgery, left ventricular aneurysm resection or any other cardiac or aortic surgery, surgery for arrhythmia, angioplasty or thrombolytic therapy were excluded Intra aortic balloon pump (IABP) insertion was required in none (0 %) patients preoperatively.IABP was inserted in 2 (2 %) patients intraoperatively before being weaned off CPB.
Follow up was completed for all 93 (100 %) patients surviving early postoperative period.Information was obtained from the patient interview and examination or by phone calls to the cardiologist or physicians.Postoperative follow-up included clinical assessment and transthoracic echocardiography.Angiography was not performed routinely during follow up.TECHNIQUE Ninety (93 %) procedures were performed using CPB and hypothermia of 32° Centigrade.Roller pump and membrane oxygenators were used in all of these procedures.Seven procedures (7 %) were off pump coronary artery bypass graft (OPCAB).
Distal anastomoses were performed during cross clamp time and aortic anastomoses were carried out using tangential aortic clamping with empty fi brillating or beating heart.Total number of grafts was 334.Mean number of grafts per patient was 3.4 (2-5).Left internal mammary artery (LIMA) graft was used in 90 (93 %) procedures.
Cold crystalloid cardioplegia (St.Thomas solution) was used in 50 (56 %) procedures.Cold blood cardioplegia was used in 40 (44 %) procedures.The method of cardioplegia insertion was antegrade and intermittent (into grafts being already constructed).Mean CPB time Myocardial revascularisation in patients with severe left ventricular dysfunction.Early and midterm results and/or NYHA.None (0 %) of surviving patients had class IV symptoms of angina/dyspnoea CCS/NYHA.

DISCUSSION
A number of studies have concluded that CABG in patients with left ventricular dysfunction provide better prognosis than conservative treatment (1.3-5).Alderman et al. 4 reported a 5 years survival rate of 43 % for the medical group compared to 63 % for the surgical group.The criteria determining impaired ventricular function are diff erent.
The predictive value of viability assessment with quantitative positron emission tomography for symptomatic and functional outcome for coronary artery surgery as treatment for ischemic heart failure has been shown by Pagano 2 .
Results supporting the use of CABG in patients with severe left ventricular dysfunction without case selection on the basis of viability studies or visibility of distal vessels has been reported by Mickleborough 6 .Nevertheless the degree of improvement in left ventricular function after revascularisation is dictated by the amount of viable myocardium 2,8 .
The limitations of the study are the fact that preoperative stress-thallium scintigraphy data were obtained in only 40 (41.2 %) patients.Stress dobutamine echocardiography was assessed in only 45 (46 %) patients.We used left ventricular ejection fraction assessed by echocardiography, ventriculography and CI in some patients to gain left ventricular function preoperatively.No control angiograms and ventriculography were performed in our patients during follow up as long as there was indication for it (sign of myocardial ischemia).
Echocardiography was used to assess ejection fraction postoperatively.A distinct LVEF improvement was showed comparing those two variables (preoperative and postoperative) assessed by ECHO.
The operative mortality rate in patients undergoing CABG is associated with several risk factors as female gender, advanced age, obesity, severity of coronary artery disease, low cardiac index, preoperative cardiac failure etc 5,7,11 .
Less invasive cardiac surgical procedures are gaining increased interest among the surgical community.Multi- Peroperative or postoperative myocardial infarction was defi ned as the appearance of a new Q wave with an elevation of the Troponin I isoenzyme higher than 1.5 µkat/l.

DATA ANALYSIS
Statistical analysis was performed using a paired t-test.A p-value less then 0.05 was considered signifi cant.

Midterm results
Mean follow up was 13 (12-16) months.No patient was lost to follow up.One year survival rate was 95.6 % (89 patients).Four patients (4.3 %) died.The cause of death was heart failure several months after surgery in 2 cases (50 %), cerebral stroke in 1 case (25 %) and unknown cause of death also in 1 case (25 %).Transthoracic echocardiography was performed in 89 (100 %) of surviving patients one year after surgery.Left ventricular EF measured by echocardiography improved from 23.1 % preoperatively to 36 % one year after surgery (Fig. 1).Mean CCS class of angina of all survivors was 1.6 and mean class of NYHA was 1.7.43 (48.3 %) patients were angina free, 17 (18.2%) patients had symptoms of class III CCS vessel off -pump coronary artery bypass (OPCAB) surgery has been made possible by the development of innovating techniques and various stabilisation systems).OPCAB operations has been demonstrated by several authors to reduce postoperative morbidity and mortality in high-risk patients [9][10][11] .We performed 7 (7 %) of our operations using OPCAB technique, fi nding it less comfortable when manipulating the heart.
The previous study comparing techniques of cardiac arrest of Brat et al. approves that cold blood cardioplegia causes less myocardial damage when compared with cold crystalloid cardioplegia 12,13 .Similarly early functional restoration of myocardium accelerates by using cold blood cardioplegia 13 .We used both of these two techniques of cardiac arrest almost equally for.
Our fi ndings are consistent with the concept that preoperative angina predicts good results, but its absence is not associated with poor results.An operative mortality of 4 % and medium term survival in our group of patients showed that surgery could be performed safely with very good symptomatic relief.Quality of life improvement confi rmed objectively with ejection fraction improvement were of clinical relevance (e.g.relief of angina and absence of heart failure symptoms).
Our fi ndings suggest that CABG in patients with poor left ventricular function is indicated not only when angina is the predominant symptom.Its absence however is not necessarily associated with poor results 6 .

CONCLUSION
Given that myocardial revascularisation in patients with severe ischemic left ventricular dysfunction is associated with higher operative risk the analysis of early postoperative results showed the operative risk in such group of patients undergoing elective surgery is not necessarily associated with high mortality.Early postoperative morbidity was certainly high, but just ten patients suff ered from such serious complications as severe renal dysfunction with the necessity for haemodialysis, ventricular arrhythmia, septicaemia, low cardiac output (LCO), intraoperative myocardial infarction so far.The midterm results (mortality, ejection fraction improvement and clinical status improvement) are also very encouraging.They strongly support safe surgical procedures with good symptomatic relief and an excellent midterm survival.

Table 5 .
Preoperative variables of left ventricle.