Incidence and prognostic significance of intraventricular conduction abnormalities after coronary bypass surgery

Outcomes of Transcatheter Aortic Valve Implant Among Patients With A Previous Coronary Artery Bypass Graft: A Nationwide Analysis

There is a paucity of data regarding the temporal trends and outcomes of transcatheter aortic valve implant (TAVI) among patients with a previous coronary artery bypass graft (CABG) surgery. We queried the Nationwide Readmissions Database (2016 to 2019) for hospitalized patients who underwent TAVI using the appropriate International Classification of Diseases, Tenth Revision procedural codes. A multivariable regression analysis was used to adjust for the patients' and hospitals' characteristics in comparing the study groups. The primary outcome was in-hospital mortality. The final analysis included 237,829 patients who underwent TAVI, of whom 42,671 (17.9%) had a previous CABG. During the study period, there was a decrease in the proportion of patients with previous CABG who underwent TAVI (21.0% in 2016 vs 15.5% in 2019, ptrend = 0.01), although there was no change in their in-hospital mortality rate (1.08% in 2016 vs 1.25% in 2019, ptrend = 0.43). Patients with a previous CABG were younger and less likely to be women than those without a previous CABG. TAVI among those with a previous CABG was associated with lower in-hospital mortality (adjusted odds ratio [aOR] 0.79, 95% confidence interval [CI] 0.69 to 0.91), similar rate of ischemic stroke (aOR 0.81, 95% CI 0.71 to 0.93) and permanent pacemaker implant (aOR 1.00, 95% CI 0.93 to 1.05). Patients with a previous CABG had a lower all-cause 90-day readmission (odds ratio 0.95, 95% CI 0.94 to 1.06) but higher readmission for transient ischemic attack. Among those with a previous CABG, female gender and chronic kidney disease stage ≥3 were independently associated with a higher in-hospital mortality, whereas obesity was associated with a lower in-hospital mortality. In conclusion, there was a decrease in the proportion of patients with a previous CABG among those who underwent TAVI. TAVI among those with a previous CABG was not associated with increased in-hospital adverse events or 90-day all-cause readmissions.

Diagnostic dilemma of perioperative myocardial infarction after coronary artery bypass grafting: A review

Coronary artery bypass grafting (CABG) is one of the most commonly performed cardiac procedures in the United States (US) and Europe. In the US, perioperative morbidity and mortality related to CABG are below 5%. One of the most significant complications following CABG, however, is perioperative myocardial infarction (PMI). Cardiac biomarkers, intra- and post-operative echocardiography, and electrocardiography are routinely used to monitor for evidence of PMI. In this review, we seek to summarize how each of these modalities is used in the clinical setting to differentiate PMI from expected procedure-related changes, and how these findings impact patients' outcomes. We conclude that while no perfect diagnostic test for the detection of clinically meaningful PMI exists, using a combination of existing modalities with knowledge of expected post-procedure changes allows for early and reliable detection. Future development is needed to create more sensitive and specific modalities for the detection of PMI in patients undergoing CABG.

Cardiac electrophysiology in mice: a matter of size

Over the last decade, mouse models have become a popular instrument for studying cardiac arrhythmias. This review assesses in which respects a mouse heart is a miniature human heart, a suitable model for studying mechanisms of cardiac arrhythmias in humans and in which respects human and murine hearts differ. Section I considers the issue of scaling of mammalian cardiac (electro) physiology to body mass. Then, we summarize differences between mice and humans in cardiac activation (section II) and the currents underlying the action potential in the murine working myocardium (section III). Changes in cardiac electrophysiology in mouse models of heart disease are briefly outlined in section IV, while section V discusses technical considerations pertaining to recording cardiac electrical activity in mice. Finally, section VI offers general considerations on the influence of cardiac size on the mechanisms of tachy-arrhythmias.

Does Combination of Antegrade and Retrograde Cardioplegia Reduce Coronary Artery Bypass Grafting-Related Conduction Defects?

BACKGROUND

Conduction disorders appearing after coronary artery bypass surgery (CABG) may have many different causes. In this study, we evaluated the postoperative conduction disorders after CABG with respect to the ante-grade blood cardioplegia and ante-grade plus continuous retrograde cardioplegia delivery methods.

MATERIALS AND METHODS

This retrospective study included 1824 patients undergoing CABG between January 2001 and December 2005. There were 694 female patients (38%) and 1130 male patients (62%). Myocardial protection was done by isothermic hyperkalemic blood cardioplegia. Patents in Group 1 (n = 704) were operated on using only intermittent antegrade cardioplegia and those in group 2 (n = 1120) were operated on using the antegrade plus retrograde continuous cardioplegia. The postoperative occurrences of a new right bundle branch block, left anterior hemiblock, left posterior hemiblock, left bundle branch block, or third-degree atrioventricular block were evaluated and compared.

RESULTS

Total mortality rate was 1.6% (29 patients) without significant difference between the groups. The preoperative and perioperative characteristics were statistically similar in the groups. The occurrence of conduction disorders was significantly higher in group 1 (P = .006, 55 versus 52 patients). The analysis of the patients with conduction disorders showed a significantly increased mortality rate (P < .001) in addition to a significantly increased period of intensive care unit follow-up and duration of postoperative hospitalization (P <.001).

CONCLUSION

The present study demonstrated that the perioperative occurrence of conduction disorders after CABG was decreased by antegrade controlled and retrograde continuous combination cardioplegia.

Fascicular Conduction Disturbances After Coronary Artery Bypass Surgery: A Review With a Meta-Analysis of Their Long-term Significance

Fascicular conduction abnormalities are frequently reported following adult cardiac surgery, but their pathogenesis and long-term outcomes remain unclear. In this article, we review the epidemiological features, pathogenesis, diagnosis, and management, and the short-term and long-term significance of fascicular conduction abnormalities following coronary artery bypass graft (CABG) surgery, based on data from 30 studies. Conduction disturbances have an incidence of 3.4% to 55.8% after CABG surgery, the most common being right bundle branch block (RBBB). RBBB is usually transient and benign. Although a slew of factors have been implicated in the pathogenesis of fascicular conduction disturbances, the two most important factors are myocardial ischemia and type of cardioplegia. While a 12-lead electrocardiogram is the gold standard for diagnosis, additional tests such as myocardial enzymes or echocardiography may have additional diagnostic and prognostic value. Short-term prognosis after RBBB is good, but its impact on long-term survival is unclear. We conducted a meta-analysis, the first of its kind in this area, using long-term survival data from five studies. There was no difference in long-term survival between patients who developed conduction disturbances after CABG surgery, and those who did not, indicating a benign influence of conduction disturbances on long-term survival, and the lack of the necessity for monitoring or pacing. While the older literature reported an adverse impact of fascicular conduction disturbances on long-term survival, the more recent studies report a substantially reduced mortality after CABG surgery, despite a higher incidence of conduction disturbances, pointing to the effect of improved surgical techniques.

Cardiac arrhythmias in cardiothoracic surgery

Most patients with cardiopulmonary disease are predisposed to develop perioperative arrhythmias with the individual patient risk depending upon the type of operative procedure performed, the risk profile of the patient, and the complexity of the post-operative course. There are several management options that may tend to prevent perioperative arrhythmias that should be considered in certain patient subsets. Most important of these is the use of beta-blocker therapy before and after operation in patients with coronary risks factors undergoing non-cardiac thoracic procedures and in patients having coronary artery bypass grafting. The common supraventricular arrhythmias including atrial fibrillation and flutter, multifocal atrial tachycardia, and paroxysmal supraventricular tachycardia must be properly diagnosed and treated appropriately. Placement of atrial pacing wires for use after open cardiac surgery is of great value both for diagnosis, and in some cases, for treatment of arrhythmias. Fortunately, serious life threatening ventricular arrhythmias occurs less commonly but the clinician must recognize and correct important predisposing factors and know how to treat these when they occur. A specific protocol for arrhythmia management that sets guidelines for drug choice and therapies for each of the common arrhythmias is useful for clinicians and adds predictability to patient care.

Impaired conduction in the bundle branches of mouse hearts lacking the gap junction protein connexin40

BACKGROUND

Connexin (Cx)40 and Cx45 are the major protein subunits of gap junction channels in the conduction system of mammals. To determine the role of Cx40, we correlated cardiac activation with Connexin distribution in normal and Cx40-deficient mice hearts.

METHODS AND RESULTS

Epicardial and septal activation was recorded in Langendorff-perfused adult mice hearts with a 247-point compound electrode (interelectrode distance, 0.3 mm). After electrophysiological measurements, hearts were prepared for immunohistochemistry and histology to determine Connexin distribution and fibrosis. In both wild-type and Cx40-deficient animals, epicardial activation patterns were similar. The right and left ventricular septum was invariably activated from base to apex. Histology revealed a continuity of myocytes from the common bundle to the septal myocardium. Within this continuity, colocalization was found of Cx43 and Cx45 but not of Cx40 and Cx43. Both animals showed similar His-bundle activation. In Cx40-deficient mice, the proximal bundle branches expressed Cx45 only. The absence of Cx40 in the proximal bundles correlated with right bundle-branch block. Conduction in the left bundle branch was impaired as compared with wild-type animals.

CONCLUSIONS

Our data show that (1) in mice, a continuity exists between the common bundle and the septum, and (2) Cx40 deficiency results in right bundle-branch block and impaired left bundle-branch conduction.

Lipoprotein(a) associated with coronary artery disease in older women: age and gender analysis

BACKGROUND

Lipoprotein (a) has been associated with increased coronary artery disease (CAD) risk in men, but relatively little data exists in women. While age influences the cardiovascular risk associated with Lp(a) in men, little is known about this phenomenon in women. The impact of gender on Lp(a) has not been fully studied in an ongoing clinical practice.

METHODS AND RESULTS

Baseline Lp(a) values were measured in 918 CAD and 829 non-CAD patients (603 females, 1144 males) entering an outpatient prevention clinic. The age-specific association of elevated Lp(a) (> 30 mg/dl) with CAD was examined after adjustment for traditional risk factors. Lp(a) was a significant risk factor (OR = 1.9, CI, 1.4-2.6) in men and women (OR = 1.9, CI 1.3-2.9). In men age < or = 55 years the odds ratio for increased cardiovascular risk in high vs low Lp(a) was 2.5 (CI 1.6-3.9). In men < or = 55, CAD increased from 32 to 61% as Lp(a) progressively rose from < or = 5 to > or = 45 mg/dl (P value for trend < 0.001). No significant increase was observed in men > 55 years (OR = 1.3, CI 0.9-2.1). In women < or = 55 years, the risk of CAD increased from 22 to 35% (OR 1.6, CI 0.8-3.2), and increased from 38 to 63% in women > 55 (OR 2.1, CI 1.3-3.5). Further, of high-risk patients (men < or = 55 and women > 55 years) with an Lp(a) in the range of 20-44 mg/dl (third quartile), younger men showed a greater incidence of CAD (51%) than older women (43%). Both genders revealed substantial risk when the Lp(a) values were above 45 mg/dl. (OR = 3.7, CI = 2.0-6.8 in younger men; OR = 3.3, CI = 1.6-6.6 in older women).

CONCLUSIONS

In this cross sectional study of both men and women, elevated Lp(a) was associated with a significantly increased risk of CAD in men and women. While we corroborate previous reports on the lack of association in older men, the determination of an enhanced Lp(a)-related risk in older women was new and unanticipated. Further, in this population of high risk patients, substantial cardiovascular risk appeared to be represented by higher concentrations of Lp(a) in women than observed in men.

HDL Cholesterol Level Predicts Survival in Men After Coronary Artery Bypass Graft Surgery

Background —HDL cholesterol (HDL-C) is an important independent predictor of atherosclerosis, yet the role that HDL-C may play in the prediction of long-term survival after CABG remains unclear. The risk associated with a low HDL-C level in post-CABG men has not been delineated in relation to traditional surgical variables such as the use of arterial conduits, left ventricular function, and extent of disease.

Methods and Results —We performed a prospective, observational study of 432 men who underwent CABG between 1978 and 1979 in whom preoperative HDL-C values were available. Baseline lipid and lipoprotein values, history of diabetes mellitus and hypertension, left ventricular ejection fraction, extent of disease, and use of internal thoracic arteries were recorded. Hazard ratios (HRs) were determined in the patients with and without a low HDL-C level, which was defined as the lowest HDL-C quartile (HDL-C ≤35 mg/dL). After adjustment for age, as well as for baseline metabolic parameters and surgical variables just noted, HDL-C corresponded to both overall (HR 0.40, CI 0.20 to 0.83, P =0.01) and event-free (HR 0.41, CI 0.24 to 0.70, P =0.001) survival. Patients with a high HDL-C level (>35 mg/dL) were 50% more likely to survive at 15 years than were patients with low HDL-C level (≤35 mg/dL) (74% versus 57% adjusted survival, respectively; HR 1.72, P =0.005). In addition, HDL-C showed a strong effect on time-to-event survival such that patients with an HDL-C level of >35 mg/dL were 50% more likely to survive without a subsequent myocardial infarction or revascularization (HR 1.42, P =0.02).

Conclusions —HDL-C is an important predictor of survival in post-CABG patients. In this study of >8500 patient-years of follow-up, HDL-C was the most important metabolic predictor of post-CABG survival. One third fewer patients survive at 15 years if their HDL-C levels are ≤35 mg/dL at the time of CABG. The measurement of HDL-C provides a compelling strategy for the identification of high-risk subsets of patients who undergo CABG.

Significance of right bundle branch block in the diagnosis of myocardial ischemia in patients undergoing coronary artery bypass grafting

BACKGROUND

Perioperative diagnosis of myocardial ischemia following cardiac surgical procedures remains a challenging problem. Particularly, the role of new conduction disturbances as markers of postoperative ischemia is still questionable. The goal of this study was to elucidate the diagnostic significance of new postoperative right bundle branch block (RBBB) for the detection of perioperative myocardial ischemia in patients undergoing elective coronary artery bypass grafting (CABG).

METHODS

In 169 consecutive patients, three-channel Holter monitoring and serial assessment of serum enzymes were performed for 48 h, and 12-lead ECG repeated for up to 5 days postoperatively. Postoperative events were classified as either myocardial infarction (MI), transient ischemic events (TIE) or various conduction disturbances.

RESULTS

Transient (n=9) or permanent (n=4) RBBB occurred in 13 patients (8%); 14 patients (8%) showed signs of perioperative MI and 18 patients (11%) evidence of TIE. Peak activity of creatine-kinase (CK, 561+/-135 vs. 316+/-19, P<0.05) and CK-MB (22.7+/-3.2 vs. 13.4+/-0.8, P<0.01) were higher in patients with RBBB than in patients without perioperative ischemic events. Peak CK-MB levels were significantly higher in patients with MI as compared to those with RBBB (33.4+/-7.6 vs. 22.7+/-3.2, P<0. 05). Patients with TIE had similar perioperative enzyme levels as patients with no events.

CONCLUSION

It is concluded that the combined assessment of repeated 12-lead ECG, continuous Holter monitoring and enzyme analysis allows a reliable diagnosis of perioperative myocardial ischemia and conduction disturbances. The occurrence of new RBBB following elective CABG is indicative of perioperative myocardial necrosis and thus serves as a valuable tool for the diagnosis of new, perioperative ischemic events.

Cardiac rehabilitation participation patterns in a large, tertiary care center: evidence for selection bias

BACKGROUND

Clinical practice guidelines have been published for cardiac rehabilitation, directing programs to address secondary risk-reduction issues. The role of risk factor profiles in the referral of patients to cardiac rehabilitation programs has not been evaluated.

METHODS

Patients from the Cardiovascular Information Registry at the Cleveland Clinic Foundation (CCF) who entered the CCF hospital-based cardiac rehabilitation program (n = 371) were compared with those who did not participate in the CCF program (n = 2960) with respect to gender, demographics, and risk factor profile for CAD. A random subset of those who did not participate in the CCF program (n = 100) was interviewed by phone to determine participation patterns in other rehabilitation programs.

RESULTS

Only 11% of patients participated in CCF-based program. Standard risk factors were similar between participants and nonparticipants. Rehabilitation patients were younger (63 +/- 10 versus 66 +/- 10, P < 0.01) and as a group had better left ventricular function (moderate-severe left ventricle: 16% versus 23%, P < 0.01) than nonparticipants. Women were underrepresented in the CCF rehabilitation population (20% versus 30%, P < 0.01). Of the phone survey sample, 21% of patients entered other community-based rehabilitation programs. Similar trends with respect to risk factors, younger age, and better left ventricular function were noted for the community subset. However, women accounted for a greater percentage of the participants in the community programs than the CCF-based program (42.8% versus 19.7%, P < 0.03).

CONCLUSIONS

Conclusions based on institution-specific programs likely underestimate overall participation in cardiac rehabilitation. Traditional risk factors apparently are not considered when referring patients to cardiac rehabilitation programs. Younger patients with lower mortality risks preferentially participate in rehabilitation programs. Women are more likely to participate in community-based programs. Overall use of cardiac rehabilitation programs remains low.

Homocysteine and lipoprotein(a) interact to increase CAD risk in young men and women

A biochemical link between homocysteine (tHcy) and lipoprotein(a) [Lp(a)] related to fibrin binding has been proposed. This hypothesis has not been specifically examined in human subjects. We sought to determine in a clinical setting whether these risk factors would interact to increase coronary artery disease (CAD) risk. We performed a cross-sectional analysis of 750 men and 403 women referred to a preventive cardiology clinic at the Cleveland Clinic Foundation, in whom baseline tHcy and Lp(a) data were available. Logistic regression after adjusting for standard cardiovascular risk factors was used to estimate the relative risk of CAD in patients with an Lp(a) >/=30 mg/dL and a tHcy >/=17 micromol/L. Neither isolated high tHcy (odds ratio [OR]=1.06, P=0.89) nor isolated high Lp(a) (OR=1.15, P=0.60) appeared to be associated with CAD in women. However, strong evidence of an association was seen when both risk factors were present (OR=4.83, P=0.003). Moreover, this increased risk showed evidence of an interactive effect beyond that attributable to either additive or multiplicative effects of tHcy and Lp(a) (P=0.03). In contrast, both elevated tHcy (OR=1.93, P=0. 05) and elevated Lp(a) (OR=1.87, P=0.01) showed evidence of being independent risk factors for CAD in men. The presence of both risk factors in men did not appear to confer additional risk (OR=2.00, P=0.09), even though ORs as high as 12.4 were observed within specific age intervals. Consistent with prior studies, tHcy and Lp(a) are risk factors, either independently or in concert, for CAD in this clinical population. More significantly, we found evidence that when both risk factors were present in women, the associated risk was greater than what would be expected if the 2 risks were simply acting independently. The absence of such an interactive effect in men may be due to the confounding effects of age manifested as "survivor bias." These clinical findings provide insights into the potential roles of both tHcy and Lp(a) in the pathogenesis of atherosclerosis.

Right bundle branch block: varying electrocardiographic patterns. Aetiological correlation, mechanisms and electrophysiology

Ten dissimilar electrocardiographic (ECG) patterns associated with right bundle branch block (RBBB) are presented. Electrophysiologic basis of the changes is discussed and possible causes for such diversity outlined. We have not found any aetiological association to this variation. The morphological diversity in RBBB patterns is likely to be related to multiple factors--site of block, nature of defect (functional, necrosis, fibrosis), degree of conduction delay, and associated pathologies with their own ECG patterns. Distinguishing RBBB from a normal ECG-variant like rsr' is particularly important when associated with left hemiblocks as the latter situation warrants extensive cardiac evaluation.

Significance of coronary artery bypass grafting-associated conduction defects

The incidence of permanent atrioventricular conduction defects (CDs) caused by coronary artery bypass grafting (CABG) varies from 5% to 43% if cold crystalloid or blood cardioplegia is used for myocardial preservation. However, the long-term effects of CDs on clinical outcome are not well known. In this study we compared the outcome of 52 patients with permanent CABG-associated CDs (CD+) to 47 patients without CDs (CD-) after a 3-year follow-up. Recovery of CDs was found in 2 patients during the follow-up. There were no significant differences between groups in late mortality, cardiac or neurologic events, or capability to work. Although exercise capacity was similar, the exercise-limiting symptom more often was chest pain or dyspnea in the CD+ group than in the CD- group (p = 0.001). Left ventricular ejection fractions at rest and at 50-W workload level were lower in the CD+ group (p = 0.03 to 0.05). In addition, CD+ patients with left bundle branch block or cardiac pacemaker had significantly lower ejection fraction at maximal workload level than patients without CDs (p = 0.03). No significant differences were observed between the groups in the potential risk for ventricular arrhythmias according to signal-averaged electrocardiograms. In conclusion, the clinical outcome of patients with CDs after CABG operations is almost comparable to those without CDs during a 3-year follow-up. However, patients with CDs have lower left ventricular systolic function and more often have chest pain or dyspnea as the exercise-limiting symptom than patients without CDs.

Pathogenesis and prognostic significance of conduction abnormalities after coronary bypass surgery

Of 200 men who underwent isolated coronary bypass graft surgery, 40 (20%) developed new postoperative, persistent conduction abnormalities. The pathogenesis of conduction abnormalities was examined by relating their presence to that of significant proximal left coronary disease before surgery, and to various intraoperative factors that included indices of myocardial preservation and revascularization. Proximal left coronary disease was observed in 92 (46%) of 200 patients, of whom 27 (29%) developed conduction abnormalities. In contrast, of the 108 patients without proximal left coronary disease, only 13 (12%) developed persistent conduction abnormalities (P < 0.01). Intraoperative factors appeared to have little or no role in the development of such abnormalities. It is concluded that the development of persistent postoperative conduction abnormalities is related more to proximal left coronary disease than to intraoperative factors and that such abnormalities do not progress during long-term follow-up (average 53 months).

Cardiac pacing following surgery for acquired heart disease

BACKGROUND

This study is comprised of 3493 consecutive patients who underwent open heart surgery at our institution. Data on all patients were collected prospectively.

METHODS

In 45 patients (Group P) (1.3%), a permanent pacemaker (PP) was inserted postoperatively. For the purpose of the study, these patients were compared to 3448 patients (Group NP) who did not require insertion of a PP after surgery. Mean follow-up was 33 months (range 1.5 to 66).

RESULTS

We found Group P patients were older (64.8 +/- 11.0 vs 61.0 +/- 11.0 years, p < 0.05), had a higher proportion of elderly (> 70 years) 36% vs 19%, p = 0.01), and of female patients (48.8% vs 22.7%, p < 0.001) compared to Group NP. Group P also had a higher incidence of preoperative rhythm abnormalities (26.6% vs 5.7%, p < 0.0001), redo surgery (13.3% vs 4.6%, p = 0.02), aortic valve surgery (48.8% vs 10.8%, p < 0.001), and tricuspid valve surgery (repair 3, replacement 1) (8.8% vs 0.5%, p < 0.001), in addition to a higher proportion of patients in whom cold (vs warm) blood cardioplegia was used (68.8% vs 52.3%, p = 0.03). Indication for postoperative PP was sick sinus syndrome (SSS) in nine patients; atrial fibrillation in eight patients; atrioventricular block (AVB) in 27 patients; and combined AVB/SSS in 1 patient. There were no operative deaths in Group P. Necessity for PP after heart surgery had a significant impact on resource utilization resulting in prolonged ventilation (3.1 +/- 7.5 vs 1.4 +/- 3.3 days, p < 0.01), intensive care unit (5.1 +/- 10.2 vs 2.5 +/- 4.0 days, p < 0.01), and postoperative hospital stay (18.0 +/- 13.4 vs 8.1 +/- 9.4 days, p < 0.01).

CONCLUSIONS

By multivariate logistic regression (odds ratio and p value in parentheses), aortic valve surgery (8.23, p = 0.001), the absence of preoperative sinus rhythm (5.60, p = 0.001), postoperative myocardial infarction (3.46, p = 0.024), and female gender (2.52, p = 0.003), were found to be independent predictors for PP requirement post surgery.

Frequency and significance of conduction defects early after orthotopic heart transplantation

To define the clinical significance of conduction defects after orthotopic heart transplantation sequential electrocardiograms (ECG) of 124 patients were analyzed during their postoperative hospital stay. The first ECG was abnormal in 90 patients (73%), with a predominance of right bundle branch block, and normal in 34 (27%). Sex, age, mean donor ischemic time, duration of aortic cross clamping and use of previous antiarrhythmic therapy were not significantly different in the 2 groups. During hospital follow-up, patients were grouped according to evolution of the initial electrocardiographic abnormalities. In group 1, 25 patients continued to have an initially normal ECG. In groups 2 and 3, 30 and 48 patients, respectively, had evidence of transient and permanent conduction defects. The 21 patients in group 4 showed progressive deterioration of conduction with either a new (9 patients) or worsening preexisting conduction defect (12 patients). The evolution of the initial ECG was strongly dependent on the duration of the donor heart ischemic time and the severity of the in-hospital cardiac rejection. Patients with persistent conduction abnormalities had a statistically longer ischemic time than either patients with normal or transient conduction defects (182 +/- 84 vs 144 +/- 68 and 130 +/- 66 minutes, p = 0.04). Although the overall percentage of patients with histologic evidence of moderate to severe rejection was similar across the groups, 66.6 and 46.1% of patients in groups 3 and 4, respectively, had multiple episodes of rejection compared with 16.6 and 0% in the remaining 2 groups (p = 0.044).(ABSTRACT TRUNCATED AT 250 WORDS)