Synergism between infarct-borne left ventricular dysfunction and cardiomegaly in increasing the risk of coronary bypass surgery

Clinical significance of cardiomegaly caused by cardiac adiposity

Enlarged cardiac silhouette on chest x-ray (CXR) in the absence of cardiopulmonary disease is often dismissed as "pseudocardiomegaly." We aimed to assess the impact of epicardial adipose tissue (EAT) on radiographic heart size and to determine the clinical significance of cardiomegaly caused by EAT. In total 112 patients (52 ± 13 years old, 53% women, body mass index 32 ± 8 kg/m(2)) with structurally normal hearts by transthoracic echocardiography underwent cardiac computed tomography (CCT). EAT volume was measured by CCT and cardiothoracic ratio (CTR) and cardiac transverse and lateral horizontal transverse diameters were measured on posteroanterior and lateral view CXR. EAT volume (mean 122 ± 49 ml) correlated directly with age, body mass index, hypertension, hyperlipidemia (p <0.05 for all comparisons), transverse diameter (r = 0.50, p <0.001), CTR (r = 0.45, p <0.001), and lateral horizontal transverse diameter (r = 0.38, p <0.001). EAT volume was larger in those with increased (n = 22) compared to those with normal (n = 90) CTR (154 ± 54 vs 115 ± 54 ml, p = 0.0005). Patients with cardiomegaly were also older (58 ± 13 vs 50 ± 12 years old, p = 0.009) and more often had diabetes (32% vs 9%, p = 0.03), hypertension (86% vs 46%, p = 0.001), hyperlipidemia (68% vs 44%, p = 0.04), or obstructive coronary artery disease by CCT (32% vs 11%, p = 0.04). Coronary artery calcium score was also higher in those with cardiomegaly (median 56 [first tertile 0, third tertile 298] vs 0 [0, 55], p = 0.006). In conclusion, cardiomegaly on CXR can be caused by excessive EAT. This is associated with several coronary risk factors and with coronary calcification and stenosis. Cardiomegaly in this setting may be regarded as another noninvasive marker of coronary atherosclerosis.

Off-pump multivessel coronary artery surgery in high-risk patients

BACKGROUND

Coronary artery bypass surgery on cardiopulmonary bypass is associated with significant morbidity and mortality, which may be more marked in high-risk patients. We evaluated our results of off-pump coronary artery bypass (OPCAB) in high-risk patients with multivessel coronary artery disease and compared them with results in similar patients who underwent operation on cardiopulmonary bypass.

METHODS

A total of 1,075 patients who underwent OPCAB between October 1996 and June 2001 and who had one or more of the following risk factors were included in the study: poor left ventricular function (EF < or = 30%), advanced age (> 70 years), left main stenosis, acute myocardial infarction, and redo coronary artery surgery. These patients were compared with 2,312 similar patients who underwent coronary artery bypass grafting on cardiopulmonary bypass during the same period. Preoperative risk factors, intraoperative variables, and postoperative results were analyzed and compared between two groups.

RESULTS

The average number of grafts was 3.0 +/- 0.4 and 3.2 +/- 0.3 in the off-pump (OPCAB) and on-pump (CCAB) groups, respectively. Hospital mortality was 3.2% and 4.5% in OPCAB and CCAB groups respectively (p = 0.109). Perioperative myocardial infarction, requirement of inotropic agents, stroke, and renal dysfunction were comparable in two groups. Intubation time (19 +/- 5 vs 24 +/- 6 hours, p < 0.001), mean blood loss (362 +/- 53 vs 580 +/- 66 mL, p < 0.001), atrial fibrillation (14.3 vs 19.7%, p < 0.001), and prolonged ventilation (4.6 vs 7.6%, p = 0.002) were less in OPCAB group. Intensive care unit stay (20 +/- 8 hours) and hospital stay (6 +/- 3 days) were significantly less in the OPCAB group (p < 0.001).

CONCLUSIONS

Off-pump coronary artery surgery can be safely performed in high-risk patients with multivessel coronary artery disease. Operative mortality is comparable to that associated with on-pump surgery, and avoidance of cardiopulmonary bypass is associated with reduced postoperative morbidity in these patients.

Coronary artery bypass grafting in patients with severe left ventricular dysfunction: a prospective randomized study on the timing of perioperative intraaortic balloon pump support

In this prospective trial the results of preoperative and intraoperative IABP in coronary artery bypass graft (CABG) patients with low left ventricular ejection fraction (LVEF) were compared. Sixty CABG patients with preoperative LVEF < or = 0.30 were enrolled: in group A patients (n=30) IABP was started within 2 hours preoperatively; in group B (n=30) it was instituted intraoperatively before weaning from cardiopulmonary bypass. Cardiac performance was assessed through Swan-Ganz catheter monitoring and daily echocardiography. Hospital survival, length of IABP support, intubation, ICU and hospital stay, need for postoperative inotropic drugs and incidence of myocardial infarction were compared between the two groups. Survival in group A patients proved significantly higher (P=0.047). Cardiac performance after myocardial revascularization improved in both groups with significantly better outcomes in group A patients (P<0.001). Doses of inotropic drugs (dobutamine, enoximone) were lower in group A (P=0.001; P=0.004) and duration shorter (P<0.001; P<0.001). No major IABP-related complication was observed.

Myocardial revascularization in patients with severe ischemic left ventricular dysfunction. Long term follow-up in 141 patients

OBJECTIVES

The present study evaluates our experience with coronary bypass grafting in patients with EF < or =25%. Myocardial revascularization in this setting remains controversial because of concerns over operative mortality and morbidity and lack of functional and survival benefit.

MATERIALS AND METHODS

One hundred and forty-one patients with coronary artery disease and left ventricular ejection fraction < or =25% underwent coronary artery bypass graft between January 1988 and December 1998. Mean age at operation was 63.3 years and 81.4% were male. The major indication for surgery was angina (114 patients, 80.8%). Ejection fraction (EF), left ventricular end diastolic pressure (LVEDP) and cardiac index (CI) were used to assess left ventricular function. The number of graft was 2.7+/-1.6/patient. Internal mammary artery was used in 119 patients (84.3%). Intra aortic balloon pump was placed preoperatively in 25 patients (17.7%). Five operative risk factors were associated with a higher mortality: emergency, female sex, LVEDP, CI and NYHA class IV.

RESULTS

The operative mortality was 7% (10 patients). Left ventricular ejection fraction (assessed post operatively in 83 patients) improved from 22.2% preoperatively to 33.5% post operatively (P<0.001), mean end diastolic volume index fell from 98 to 83 ml/m(2) following surgery. Survival at 2, 5 and 7 years was respectively 84+/-3%, 70+/-4% and 50+/-5%. Two variables were associated with increased long term survival: congestive heart failure (NYHA class lower than IV (P=0.035) and cardiomegaly (P=0.04)

CONCLUSION

In patients with left ventricular dysfunction, myocardial revascularization can be performed relatively safely with good medium term survival and improvement in quality of life and in left ventricular function. Coronary artery bypass graft may be offered to patients with impaired ventricular function, but careful patient selection and management when considering these patients for operation should assess potentially reversible dysfunction.

Preoperative intraaortic balloon pump enhances cardiac performance and improves the outcome of redo CABG

BACKGROUND

Reoperative coronary artery bypass grafting (redo CABG) is associated with an increased operative risk compared with primary CABG. Because the hospital mortality in redo CABG is known to be influenced by poor left ventricular function (left ventricular ejection fraction < or = 0.40), unstable angina, and left main stem stenosis greater than or equal to 70%, a preoperative intraaortic balloon pump (IABP) support could be beneficial to improve the outcome in high-risk redo CABG.

METHODS

Between June 1994 and October 1996, 48 high-risk patients underwent redo CABG and were randomized into the following groups: group 1 (24 patients) who received preoperative IABP treatment on average 2 hours before cardiopulmonary bypass, and group 2 (24 patients) who received no preoperative IABP and served as controls. Mean age was 65 years and 90% (43 patients) were men. Forty-one patients had preoperative left ventricular ejection fraction less than or equal to 0.40 (85%), 38% (18 patients) had left main stem stenosis greater than or equal to 70%, and 54% (26 patients) had unstable angina preoperatively. Preoperative patient characteristics did not differ between the groups.

RESULTS

The time on cardiopulmonary bypass was shorter in group 1, 86 versus 110 minutes (p = 0.006). There were no hospital deaths in group 1, but four deaths occurred in the control group (p = 0.049). Cardiac index rose significantly preoperatively after introduction of the IABP in group 1. Cardiac index was significantly higher postoperatively in group 1 compared with group 2 and remained significantly higher during the first 24 hours after cardiopulmonary bypass. Significantly fewer patients in the IABP group had postoperative low cardiac output (4 versus 13 patients). Nine patients in group 2 required IABP support postoperatively for 4.1 +/- 1.7 days. Only 2 patients in group 1 needed IABP postoperatively, and their IABPs were successfully removed on the first postoperative day. The preoperative IABP-supported patients had a shorter intensive care unit stay, 2.4 +/- 0.8 days compared with group 2, 4.5 +/- 2.2 days (p = 0.007), as well as a shorter hospital stay. The preoperative IABP treatment was found to be cost-effective.

CONCLUSIONS

Preoperative treatment with IABP in high-risk redo CABG patients is an effective modality to prepare these patients to have their myocardial revascularization in an as nonischemic situation as possible, which resulted in a significantly lower hospital mortality, fewer instances of postoperative low cardiac output, and shorter stays in both the intensive care unit and the hospital.

Evaluation of preoperative intra-aortic balloon pump support in high risk coronary patients

OBJECTIVE

The intra-aortic balloon pump (IABP) is an established additional support to pharmacological treatment of the failing heart after myocardial infarction, unstable angina and cardiac surgery. The effect of preoperative IABP in high risk patients was evaluated.

METHODS

Between June 1994 and March 1996 all high risk patients for CABG (two or more of these criteria: Left ventricular ejection fraction (LVEF) < or = 40%, left main stem stenosis > or = 70%, REDO-CABG, unstable angina) were randomized into either of 3 groups: (1) IABP 1 day prior to surgery, (2) IABP 1-2 h prior to CPB and (3) no preoperative IABP, controls.

EXCLUSION CRITERIA

cardiogenic shock preoperatively. Fifty-two patients have entered the study-group 1 (13 patients), group 2 (19 patients) and group 3 (20 patients). Preoperative patient characteristics and operative data revealed no group differences. There were 56% REDO's, unstable angina 59%, LVEF < or = 40%, 87% (34.0 +/- 11.6%) and left main stem stenosis in 35%.

RESULTS

The CPB-time was shorter in groups 1 and 2 88.7 +/- 20.3 min than in group 3 105.5 +/- 26.8 min, P < 0.001, while ischemia time did not differ. Hospital mortality was higher in group 3, 25% vs. 6% (groups 1 and 2). Postoperative low cardiac output was seen in 12 patients (60%) in group 3 vs. 6 patients (19%) in groups 1 and 2, P < 0.05. Cardiac index increased significantly prior to CPB in groups 1 and 2. After CPB cardiac index was significantly higher in groups 1 and 2 compared to Group 3 and continued to increase. The IABP was removed after 3.1 +/- 1.0 days in group 3 vs. 1.3 +/- 0.6 days in groups 1 and 2, P < 0.001. In group 3, 11 patients required IABP postoperatively compared to only 4 patients in groups 1 and 2. ICU stay was shorter in groups 1 and 2--2.3 +/- 0.9 days vs. 3.5 +/- 1.1 days for group 3, P = 0.004. All patients received dopamin postoperatively, however in a lower dose in groups 1 and 2, 4.5 vs. 13.5 microg/kg/min. Dobutamine was added in 23% of the patients (group 1), 32% (group 2) and 95% (group 3). Adrenalin/amrinonum was required in 40% of the patients in group 3, 5% in group 2 and none in group 1. Group 1 patients had a better improvement of cardiac performance than group 2, while other parameters did not differ. Three months follow up of hospital survivors showed no group differences.

CONCLUSIONS

The use of preoperative IABP in high risk patients lowers hospital mortality and shortens the stay in ICU, due to improved cardiac performance, compared to a controls. The procedure was cost-beneficial. One day preoperative IABP treatment improves cardiac performance more than 1-2 h preoperative IABP treatment, but does not significantly affect the outcome in terms of hospital mortality or postoperative morbidity.

Coronary artery bypass without cardiopulmonary bypass: analysis of short-term and mid-term outcome in 220 patients

Two hundred twenty patients, preferentially those with high-risk conditions, underwent coronary artery bypass grafting without cardiopulmonary bypass. Early unfavorable outcome events included operative mortality (7 patients, 3.2%), nonfatal perioperative myocardial infarction (6 patients, 2.7%), cerebrovascular accident (1 patient, 0.4%), and sternal infection (3 patients, 1.4%). There were two deaths (13%) among 15 patients with calcified aorta and four (12%) in 33 patients who underwent emergency operation. Multivariate analysis revealed these two risk factors to be the only predictors of early mortality (odds ratios, 8.0 and 9.8, respectively). Preoperative risk factors such as left ventricular dysfunction (ejection fraction < or = 35%) (40 patients, 18%), congestive heart failure (46 patients, 21%), acute myocardial infarction (59 patients, 27%), cardiogenic shock (7 patients, 3%), age 70 years or older (59 patients, 27%), renal failure (19 patients, 9%), and cerebrovascular accident and carotid disease (11 patients, 5%) were not found to be major predictors of early mortality or unfavorable outcome. During 12 months of follow-up (range 1 to 21 months), there were four cardiac and three noncardiac deaths (1-year actuarial survival 93%) and 17 cases (7.7%) of early return of angina. Calcified aorta, nonuse of the internal mammary artery, reoperation, and diabetes mellitus were independent predictors of unfavorable events. We conclude that coronary artery bypass grafting without cardiopulmonary bypass can be done with relatively low operative mortality, although there seems to be an increased risk for early return of angina. This procedure should therefore be considered for patients with appropriate coronary anatomy, in whom cardiopulmonary bypass poses a high risk. This procedure is still hazardous with calcified aorta or emergency operation.

Left ventricular end-systolic volume index in patients with ischemic cardiomyopathy predicts postoperative ventricular function

BACKGROUND

We investigated the usefulness of the preoperative left ventricular end-systolic volume index (LVESVI) as a predictor of postoperative ventricular function.

METHODS

We retrospectively reviewed the records of 310 patients who underwent coronary artery bypass grafting and identified 20 patients with ischemic cardiomyopathy with a preoperative ejection fraction less than 0.30. We determined the preoperative and postoperative ejection fraction, LVESVI, and left ventricular enddiastolic volume index using biplane left cineventriculography. Patients were divided into groups depending on whether their preoperative LVESVI was less than 100 mL/m2 (group A, n = 10) or greater than 100 mL/m2 (group B, n = 10).

RESULTS

The mean ejection fraction increased significantly after coronary artery bypass grafting in group A from 0.25 +/- 0.05 to 0.40 +/- 0.09 (p < 0.01), but did not change significantly in group B (0.26 +/- 0.05 versus 0.23 +/- 0.06). The mean LVESVI decreased significantly in group A from 83.2 +/- 13.7 to 61.7 +/- 20.4 mL/m2 after operation (p < 0.05), but did not change significantly in group B (124.7 +/- 21.0 versus 121.5 +/- 37.6 mL/m2). In group B, 4 patients had signs of congestive heart failure during the follow-up period and had to be rehospitalized.

CONCLUSIONS

The mean ejection fraction improved significantly after coronary artery bypass grafting in patients with a preoperative LVESVI less than 100 mL/m2, despite the presence of a global left ventricular ejection fraction less than 0.30. Our results suggest that the preoperative LVESVI predicts the postoperative status and left ventricular function in patients with ischemic cardiomyopathy.

Coronary bypass with ejection fraction of 0.20 or less using centigrade cardioplegia: long-term follow-up

Forty-two patients with an ejection fraction of 0.20 or less underwent coronary artery bypass grafting from 1986 to 1990 using a method of myocardial protection we term "centigrade cardioplegia," combining single-dose, cold, crystalloid cardioplegia, systemic hypothermia, and local hypothermia. Thirty-day mortality was 4.8% (2/42). Perioperative morbidity included two myocardial infarctions (4.8%) and one stroke (2.4%), which fully resolved. Postoperative left ventricular function improved (left ventricular ejection fraction, 0.157 +/- 0.028 to 0.226 +/- 0.085; p < 0.0002), as did New York Heart Association class (3.4 +/- 0.73 to 1.8 +/- 0.63; p < 0.0001) and Canadian class (3.3 +/- 0.81 to 0.61 +/- 0.92). Survival, 88% at 1 year, declined to 68% at 3 years and 34% at 6 years. This high-risk group had very acceptable short-term results, indicating adequate intraoperative myocardial protection. Four clinical variables were associated with long-term survival: (1) chief complaint of pain only (p = 0.05), (2) history of unstable angina (p = 0.04), (3) Canadian class less than IV (p = 0.05), and (4) New York Heart Association class less than IV (p = 0.05). Reduced survival, although not statistically significant (p = 0.07), was noted for right ventricular ejection fraction of 0.30 or less. These factors may help predict which patients with severe left ventricular dysfunction will benefit from revascularization.