Heart block complicating acute inferior wall myocardial infarction

Impact of PercuSurge GuardWire device on prevention and reduction of recovery time from complete heart block in patients with acute inferior myocardial infarction undergoing primary percutaneous coronary intervention

Second-degree heart block or complete heart block (CHB) is a relatively frequent complication of acute inferior wall myocardial infarction (AIWMI). This study investigated whether the PercuSurge device can prevent procedure-related CHB or can shorten CHB recovery time in patients with AIWMI undergoing primary percutaneous coronary intervention (PCI). Between May 2002 and April 2005, a PercuSurge device was utilized in 113 patients (study population, group 1) with AIWMI due to obstruction of the right coronary artery (RCA) with a reference lumen diameter (RLD) > or = 3.5 mm. The control subjects (group 2) consisted of 119 patients who experienced AIWMI due to RCA obstruction with a RLD > or = 3.5 mm from May 2000 to April 2002. The combined incidence of new onset of CHB following the interventional procedure was significantly higher in group 2 than in group 1. Additionally, recovery time from CHB to first-degree heart block or normal sinus rhythm was remarkably longer in group 2 than in group 1. Furthermore, the duration of hospitalization in group 2 was significantly longer than in group 1. Multiple stepwise analyses demonstrated that the PercuSurge device was the only independent predictor of preventing new onset of CHB during the procedure. Additionally, this mechanical device along with final TIMI-3 flow and final myocardial blush grade > or = 2 was independently associated with reducing recovery time from CHB. In conclusion, the PercuSurge device can prevent procedure-related CHB and shorten the recovery time for CHB in patients with AIWMI undergoing primary PCI.

Temporary Pacemakers in Critically Ill Patients

Temporary cardiac pacing provides electrical stimulation to a heart compromised by disturbances in the conduction system causing hemodynamic instability. The use of a temporary pacemaker to treat a bradydysrhythmia or in some cases, a tachydysryhthmia, is undertaken when the condition is temporary and a permanent pacemaker is not necessary or available in a timely fashion. Temporary cardiac pacing is utilized in acute situations and for critically ill patient populations requiring immediate therapy. This article discusses the various indications and contraindications to temporary cardiac pacing therapy, reviews the different modalities of temporary pacemakers, and outlines critical considerations in the management of patients being treated with a temporary pacemaker.

[Prognostic significance of second and third degree atrioventricular block in acute inferior wall myocardial infarction]

High degree atrioventricular block complicates inferior wall acute myocardial infarction in 10 to 15% of cases. Its significance is still controversial. In this study, we have analysed 152 observations of acute inferior wall myocardial infarction during hospitalisation period. The mean age of our patients is 60 years, 48.7% of them have received fibrinolytic treatment. Second or third degree atrioventricular block was detected in 33 cases (21.7%). Mortality is higher in inferior wall myocardial infarctions with atrioventricular block than in those without atrioventricular block (12% versus 2.5%, p < 0.05). Hemodynamic complications like cardiogenic shock due to the extension of the infarction to the right ventricle and left ventricle insufficiency are more frequent (18% versus 3.4%, p < 0.01 and 12% versus 3.5%, p < 0.01 respectively). It appears that the infracted mass of myocardium is larger in case of atrioventricular block, this is assessed by comparing the average value of the peak of creatine Kinase in the two groups with and without atrioventricular block (1534 IU versus 1096 IU, p < 0.02) and by considering the rate of low ejection fraction (EF < 40%) in each group (44.6% versus 16%, p < 0.01). In our study, we note that thrombolysis does not affect the incidence of atrioventricular block (19% and 24% in thrombolyed and not thrombolyzed patients respectively) but it seems that thrombolysis improves the outcome of these patients. The occurrence of atrioventricular block in acute inferior wall myocardial infarction is related to the presence of an important right coronary artery that is occluded, the recanalisation of this vessel leads often to rapid regression of the block that is no longer pejorative.

Prognostic significance of right ventricular dysfunction in patients with acute inferior myocardial infarction and right ventricular involvement

Little is known about the influence of right ventricular (RV) dysfunction on prognosis of patients with acute inferior myocardial infarction (IMI) and RV involvement. Therefore, 99 consecutive patients (mean age 56.6 +/- 3.4 years) with RV involvement during acute IMI were followed for a 12-month period to clarify the influence of acute RV dysfunction on short- and long-term survivals. Forty-one patients with IMI evolved with severe arterial hypotension due to RV dysfunction, while 58 patients had no hemodynamic impairment due to RV involvement. Basal hemodynamic data (mean +/- SD) for patients with RV dysfunction were blood pressure (BP) 92/59 +/- 22/20 mmHg, systemic vascular resistance (SVR) 2314 +/- 252 dynes.s.cm-5, and cardiac index (CI) 1.3 +/- 0.3 l/min/m2. Patients without RV dysfunction demonstrated BP 113/74 +/- 20/16 mmHg (p < or = 0.05), SVR 1324 +/- 354 dynes.s.cm-5 (p < or = 0.01), and CI 2.6 +/- 0.5 l/min/m2 (p < or = 0.05). Angiographic differences noted were that hemodynamically compromised patients showed lower RV ejection fractions (0.27 +/- 0.08) than patients without hemodynamic disturbance [0.41 +/- 0.11 (p < or = 0.05)]; however, left ventricular ejection fractions were 0.48 +/- 0.10 and 0.52 +/- 0.12, respectively. Short- and long-term mortality rates were assessed during the follow-up period. Patients with hemodynamic impairment due to RV infarction had a higher mortality rate for the first month and for 11 subsequent months post MI than patients without hemodynamic impairment, that is 24.4 vs. 6.9 and 14.6 (p <or = 0.05) vs. 3.4 (p < or = 0.05), respect ively.(ABSTRACT TRUNCATED AT 250 WORDS)

Complete atrioventricular block complicating inferior acute wall myocardial infarction: short- and long-term prognosis

The incidence of complete atrioventricular block (AVB) in a large group of patients with Q-wave inferior acute myocardial infarction (AMI) was 251 (11%) of 2273 patients. This incidence was significantly higher in women (14%) and patients > 70 years old (15%) than in men and patients < 70 years old (10% and 9%, respectively). Patients with complete AVB exhibited more serious arrhythmic and mechanical complications during hospitalization and included more patients with very high enzyme levels than their counterparts without AVB. The in-hospital mortality rate was 92 (37%) of 251 patients with complete AVB versus 200 (11%) of 1890 in those without AVB (p < 0.0001). After adjustment for age, gender, and important anamnestic, medical, and enzymatic findings, complete AVB emerged as an independent predictor of in-hospital mortality, yielding an odds ratio of 2.0 (90% confidence interval 1.12 to 3.57). The long-term (5-year) mortality rate in hospital survivors was slightly but not significantly higher in patients with complete AVB (28%) during hospitalization than in their counterparts with no AVB (23%). In view of these data, patients with inferior AMI in whom complete AVB develops are at increased risk and may benefit from urgent revascularization; the postdischarge management of survivors with complete AVB should be no different from that of patients without AVB.

Prognosis of acute myocardial infarction complicated by complete heart block (the Worcester Heart Attack Study)

As part of a community-based study of patients hospitalized with acute myocardial infarction (AMI) in the Worcester, Massachusetts, metropolitan area, changes over time in the incidence rates of complete heart block (CHB) complicating AMI, and the prognostic impact of CHB on the in-hospital and long-term survival of these patients were examined. In all, 4,762 patients with validated AMI hospitalized at 16 hospitals in the Worcester metropolitan area during 1975, 1978, 1981, 1984, 1986 and 1988 constituted the study sample. The incidence rates of CHB complicating AMI remained relatively stable at 5.8% over the 13-year (1975 to 1988) period studied. The incidence rates of CHB were approximately twice as high in patients with inferior/posterior wall AMI (7.7%) as in those with anterior wall AMI (3.9%). Use of a multivariate regression analysis to control for factors affecting the incidence rates of CHB revealed that patients were at highest risk for developing CHB during the latter 2 study years (1986 and 1988). Patients with AMI developing CHB had higher in-hospital case fatality rates than did those without CHB overall, as well as during each of the 6 periods studied. The in-hospital survival associated with CHB did not improve over time. After use of a multivariate regression analysis to control for additional prognostic factors, the independent effect of CHB on in-hospital prognosis remained (adjusted risk of dying = 2.10; 95% confidence intervals = 1.37, 3.21). Patients with inferior wall AMI complicated by CHB were at significantly increased risk of dying during hospitalization compared with those without CHB (adjusted risk of dying = 2.71; 95% confidence intervals = 1.60, 4.59).(ABSTRACT TRUNCATED AT 250 WORDS)

Complete atrioventricular block complicating inferior wall acute myocardial infarction treated with reperfusion therapy. TAMI Study Group

Previous studies report larger myocardial infarcts and increased in-hospital mortality rates in patients with inferior wall acute myocardial infarction (AMI) and complete atrioventricular block (AV), but the clinical implications of these complications in patients treated with reperfusion therapy have not been addressed. The clinical course of 373 patients--50 (13%) of whom developed complete AV block--admitted with inferior wall AMI and given thrombolytic therapy within 6 hours of symptom onset was studied. Acute patency rates of the infarct artery after thrombolytic therapy were similar in patients with or without AV block. Ventricular function measured at baseline and before discharge in patients with complete AV block showed a decrement in median ejection fraction (-3.5 vs -0.4%, p = 0.03) and in median regional wall motion (-0.14 vs +0.24 standard deviations/chord, p = 0.05). The reocclusion rate was higher in patients with complete AV block (29 vs 16%, p = 0.03). Patients with complete AV block had more episodes of ventricular fibrillation or tachycardia (36 vs 14%, p less than 0.001), sustained hypotension (36 vs 10%, p less than 0.001), pulmonary edema (12 vs 4%, p = 0.02) and a higher in-hospital mortality rate (20 vs 4%, p less than 0.001), although the mortality rate after hospital discharge was identical (2%) in the 2 groups. Multivariable logistic regression analysis revealed that complete AV block was a strong independent predictor of in-hospital mortality (p = 0.0006). Thus, despite initial successful reperfusion, patients with inferior wall AMI and complete AV block have higher rates of in-hospital complications and mortality.

Mechanical and electrical complications of acute myocardial infarction

Although much of the current enthusiasm in the management of acute myocardial infarction is related to revascularization strategies, mechanical and electrical complications continue to pose a major threat to recovery in some patients. Some of the major complications of acute myocardial infarction are cardiogenic shock, rupture of the free wall and pseudoaneurysm, rupture of the ventricular septum, acute mitral regurgitation, right ventricular myocardial infarction, infarct expansion or extension, pericarditis and tamponade, peri-infarction hypertension, and tachyarrhythmias and bradyarrhythmias. For each of these complications, general guidelines for diagnosis and management are offered. Early, aggressive, and judicious treatment of these complications may substantially decrease the morbidity and mortality associated with acute myocardial infarction.

Prognostic significance of complete atrioventricular block in patients with acute inferior myocardial infarction with and without right ventricular involvement

Data were obtained and analyzed in 243 patients with acute inferior myocardial infarction who were admitted to the coronary care unit during the years 1987 and 1988. One hundred and ninety-eight patients had no signs of right ventricular involvement (group I), whereas 45 patients had inferior myocardial infarction with right ventricular infarction (group II). Patients were divided into groups depending on the presence or absence of complete atrioventricular block during hospital stay (groups Ia and IIa without block and groups Ib and IIb with block). Selected clinical and laboratory variables were compared for each group. We found that patients with inferior myocardial infarction and complete atrioventricular block had significantly higher mortality rates only in the presence of right ventricular infarction: 41% mortality rate in group IIb versus 11% mortality rate in group Ib (p less than 0.05). Patients with right ventricular infarction but without complete atrioventricular block (group IIa) had a mortality rate similar to that found in patients with inferior myocardial infarction and no atrioventricular block (group Ia): 14% versus 11% (p = NS). In patients with inferior myocardial infarction without right ventricular involvement (group I), complete atrioventricular block did not influence survival: 14% mortality rate in group Ib versus 11% mortality rate in group Ia (p = NS). The excessively high mortality rate in patients who have inferior myocardial infarction with right ventricular involvement and complete atrioventricular block could be the consequence of greater infarct size, but the synergistic influence of right ventricular infarction and complete atrioventricular block could be the other factor that influences outcome.

Temporary transvenous cardiac pacing: 6 years experience in one coronary care unit

The role of temporary percutaneous endocardial pacing has been examined in a retrospective analysis of all paced patients admitted to one coronary care unit over a 6 year period. The majority of 162 cases (84.6%) were paced for complete heart block complicating acute myocardial infarction. These patients had a higher incidence of previous hypertension, myocardial infarction and diabetes, compared to matched controls (P less than 0.05, less than 0.02 and less than 0.001, respectively). Admission blood glucose levels were also higher (P less than 0.05). The in-hospital mortality was high (46.7%), especially for those with anterior myocardial infarction (74.5%). Twenty-five (15.4%) patients without recent myocardial infarction were paced for symptomatic brady-dysrhythmias, usually due to chronic complete heart block (Lenegre's disease) or sick sinus syndrome. Most later required permanent pacing. Complications of temporary pacing were more frequent in those who died, the most common being dysrhythmias during pacemaker insertion. Review of our cases suggests that whilst facilities for temporary pacing were extremely valuable, many cases treated were not haemodynamically compromised and probably did not require pacing. Guidelines should be established on coronary care units to prevent the unnecessary morbidity, mortality and expense of the procedure.

Long-term outcome in patients with inferior myocardial infarction and complete atrioventricular block

Some studies have reported increased short-term mortality and higher incidence of multivessel coronary artery disease in patients with inferior myocardial infarction and complete heart block, but information is lacking on clinical outcome after hospital discharge. Therefore, data were obtained and analyzed in 749 patients who were admitted with inferior myocardial infarction to four different centers and followed up for 1 year. Six hundred fifty-four patients (Group 1) did not have complete heart block and 95 (Group 2) had complete heart block during their hospital stay (incidence rate 12.8%). Compared with Group 1, Group 2 patients were older (66 versus 61 years, p less than 0.01), more often had signs of left ventricular failure (p less than 0.001) and had higher peak creatine kinase values (1,840 versus 1,322 IU/liter, p less than 0.001). The in-hospital mortality rate was higher in Group 2 than in Group 1 (24.2 versus 6.3%, p less than 0.001). However, at discharge there was no difference between Group 1 and Group 2 in clinical characteristics, left ventricular ejection fraction (0.52 +/- 0.12 versus 0.52 +/- 0.11) or incidence of complex ventricular arrhythmias on ambulatory electrocardiographic monitoring. Furthermore, during the year after hospital discharge, patients in Groups 1 and 2 did not have significantly different mortality rates (6.4 versus 10.1%, p = NS). The incidence rate of reinfarction (4%) was the same in Groups 1 and 2. The incidence of coronary artery bypass surgery was slightly but not significantly higher in Group 1 compared with Group 2 (11 versus 4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Atrioventricular block in posterior acute myocardial infarction: a clinicopathologic correlation

The specialized conducting systems of 44 hearts with posterior-inferior acute myocardial infarction were studied to clarify the anatomic basis of atrioventricular (AV) block. The results showed a lack of correlation between the block and the lesional pathology of the specialized conducting system. On the other hand, an evaluation of the atrial prenodal myocardium revealed strong clinicopathologic correlation between the block and the necrotic damage to these fibers. Twenty-nine or 97% of patients with AV block showed acute necrosis of the prenodal atrial myocardium. Considering the conducting prenodal septal atrial myocardium as a suprahisian structure, the necrosis at this level would provide an anatomic basis of the block in posterior-inferior acute myocardial infarction. Analysis of the behavior of the AV block after pharmacologic treatment further established a relationship between the block and acute lesions in the central conduction system.

Atrioventricular block in acute inferior wall myocardial infarction: harbinger of associated obstruction of the left anterior descending coronary artery

In a prospective study 51 consecutive patients who survived the acute phase of inferior wall myocardial infarction underwent coronary arteriography. Eleven patients developed some degree of atrioventricular (AV) block in the acute phase of infarction that disappeared within a few days and was considered by electrocardiographic analysis to be located in the AV node. Patients with AV block during acute myocardial infarction had a significantly higher prevalence of left anterior descending coronary artery obstruction (91 versus 55%, p less than 0.05) than did patients without AV block and the obstruction preceded the exit of the first septal perforator branch in 73% of cases with heart block and in 30% of cases without block (p less than 0.01). The sensitivity, specificity and predictive values were 31, 95 and 91%, respectively, for the existence of left anterior descending coronary artery obstruction when AV block occurred during acute inferior myocardial infarction, and 40, 90 and 73%, respectively, for the occurrence of the coronary artery obstruction before the exit of the first septal perforator branch. Patients with inferior myocardial infarction and left anterior descending coronary artery obstruction have a sixfold greater chance of developing heart block in the acute phase of infarction than do patients with inferior infarction without such obstruction (p less than 0.05). These findings also support the observations that the proximal AV conduction system usually has a dual arterial blood supply from both the right and left anterior descending coronary arteries, and may explain the transient behavior of heart block and lack of necrosis of the AV node seen in these patients.

The clinical significance of bundle branch block complicating acute myocardial infarction. 1. Clinical characteristics, hospital mortality, and one-year follow-up

To provide an understanding of the clinical characteristics of patients with acute myocardial infarction (MI) and bundle branch block, experience from five centers was accumulated. Patients in whom bundle branch block first appeared after the onset of cardiogenic shock were excluded. In 432 patients, the most common types of block were left (38%) and right with left anterior fascicular block (34%). In 42% of the patients, bundle branch block was new. Progression to high degree (second or third degree) atrioventricular (AV) block via a Type II pattern occurred in 22% of the patients. Hospital and first year follow-up mortality rates were 28% and 28%, respectively. Only 46% of the patients developed pulmonary edema or shock (Killip Class III or IV), and hospital mortality was related to the amount of heart failure (8%, 7%, 27%, 83% for Killip Classes I-IV, respectively). Patients with progression to second degree or third degree AV block via a Type II pattern had increased hospital mortality compared with patients without this complication (47% vs 23%, P less than 0.001). In the absence of pulmonary edema or shock, patients with Type II second degree or third degree AV block still had a higher mortality rate than patients without advanced AV block (31% vs 2%, P less than 0.005), with nearly all the deaths due to abrupt development of AV block. Thus, in many patients MI with bundle branch block is associated with severe heart failure. However, this was not true for a majority of the patients, in whom therapy aimed at preventing morbidity and mortality due to the bradyarrhythmia of advanced AV block might be beneficial.