Atrioventricular block in posterior acute myocardial infarction: a clinicopathologic correlation

Temporary Transvenous Cardiac Pacing in Patients With Acute Myocardial Infarction Predicts Increased Mortality

Background

Temporary pacemakers (TP) are used in emergency situations for severe bradyarrhythmias secondary to acute myocardial infarction (AMI) and to non-AMI related cardiac disorders. TP have been studied previously in AMI patients treated with thrombolytic therapy; limited information is available on current outcomes in AMI patients treated with percutaneous coronary intervention.

Methods

We reviewed the indications, complications, and mortality associated with TP insertion over a four year period (2003 - 2007) at a university hospital.

Results

Seventy-three temporary pacemakers were inserted (47 men, 26 women) during this period. The mean age was 65.2 years. TP were used in 29 AMI patients (39.7 % of total) and 44 non-AMI patients (60.3% of total). The duration of TP use was 2.6 ± 0.4 days in the whole cohort, 2.46 % of all AMI patients (29/1180) admitted during this period required a TP. Six of these patients requiring a TP required a permanent pacemaker. Eight patients with AMI and a TP died (27.6%). In contrast 8.9 % of AMI patients not requiring a TP died (P < 0.01). There were no statistically significant differences between the AMI and non-AMI groups in the duration of temporary pacing (2.4 ± 0.6 days vs. 2.8 ± 0.4 days), in complications (27.6% vs. 29.5%), or in mortality (27.6% vs. 15.9%). The need for a permanent pacemaker (PPM) differed significantly between the AMI and non-AMI patients (20.7% vs. 54.5%; P < 0.05).

Conclusion

Our results indicate that AMI patients infrequently require a TP and that approximately 20% of these patients require a PPM. These results suggest that early revascularization of the conduction system with current interventional techniques has decreased the need for TP in AMI patients. However, this group requires more intensive monitoring as the mortality rate in this group of patients is significantly higher than the other AMI patients not requiring TP.

Clinical and Angiographic Findings of Complete Atrioventricular Block in Acute Inferior Myocardial Infarction

Introduction: The angiographic findings and prognosis of patients with complete atrioventricular block (AVB) complicating acute inferior myocardial infarction (MI) remain unclear. Materials and Methods: The clinical and angiographic findings of 70 consecutive patients with complete AVB were compared with those of 319 patients with inferior MI without AVB (control group) admitted within the same study period. Results: Patients with complete AVB were older (68 ± 12 vs 63 ± 13 years; P = 0.004) and clustered with clinical features indicative of larger infarct size, such as right ventricular infarction, cardiogenic shock, or low left ventricular ejection fraction (LVEF). The onset of the complete AVB was observed within 24 hours in 62 (88.6%), preceded by second-degree AVB in 26 (37.1%) and the escape QRS complex was wide in 8 (11.4%) patients. In patients with complete AVB, a dominant right coronary artery occlusion was found in >95% of cases and in-hospital mortality was increased (27.1% vs 10.7%; P = 0.000), especially in those with widen QRS escape rhythm (75.0%). Reperfusion therapy had a positive impact on the natural course of complete AVB. Conclusions: Complete AVB in acute inferior MI was associated with advanced age and larger infarct size. Complete AVB was virtually always caused by dominant right coronary artery occlusion. The in-hospital mortality was significantly higher, but improved by reperfusion therapy. No permanent pacemaker is performed at a mean follow-up of 47 months. Key words: Coronary angiography, In-hospital mortality

Comparison of different methods of ST segment resolution analysis for prediction of 1-year mortality after primary angioplasty for acute myocardial infarction

BACKGROUND

Resolution of ST segment elevation corresponds with myocardial tissue reperfusion and correlates with clinical outcome after ST elevation myocardial infarction. Simpler method evaluating the extent of maximal deviation persisting in a single ECG lead was an even stronger mortality predictor. Our aim was to evaluate and compare prognostic accuracy of different methods of ST segment elevation resolution analysis after primary percutaneous coronary intervention (PCI) in a real-life setting.

METHODS

Paired 12-lead ECGs were analyzed in 324 consecutive and unselected patients treated routinely with primary PCI in a single high-volume center. ST segment resolution was quantified and categorized into complete, partial, or none, upon the (1) sum of multilead ST elevations (sumSTE) and (2) sum of ST elevations plus reciprocal depressions (sumSTE+D); or into the low-, medium-, and high-risk groups by (3) the single-lead extent of maximal postprocedural ST deviation (maxSTE).

RESULTS

Complete, partial, and nonresolution groups by sumSTE constituted 39%, 40%, and 21% of patients, respective groups by sumSTE+D comprised 40%, 39%, and 21%. The low-, medium-, and high-risk groups constituted 43%, 32%, and 25%. One-year mortality rates for rising risk groups by sumSTE were 4.7%, 10.2%, and 14.5% (P = 0.049), for sumSTE+D 3.8%, 9.6%, and 17.6% (P = 0.004) and for maxSTE 5.1%, 6.7%, and 18.5% (P = 0.001), respectively. After adjustment for multiple covariates only maxSTE (high vs low-risk, odds ratio [OR] 3.10; 95% confidence interval [CI] 1.11-8.63; P = 0.030) and age (OR 1.07; 95% CI 1.02-1.11; P = 0.002) remained independent predictors of mortality.

CONCLUSIONS

In unselected population risk stratifications based on the postprocedural ST resolution analysis correlate with 1-year mortality after primary PCI. However, only the single-lead ST deviation analysis allows an independent mortality prediction.

Bloqueo auriculoventricular en la angina inestable. Resultados del registro ARIAM

OBJECTIVE

Describe the frequency of high degree atrioventricular block (HDAVB) in patients with unstable angina (UA), analyze the variables associated with their appearance and evaluate whether HDAVB is independently associated with increased mortality or increased length of ICU stay.

DESIGN

Retrospective descriptive study of patients with UA included in the ARIAM registry.

SETTING

ICUs from 129 hospitals in Spain.

PATIENTS

From June 1996 to December 2003 a total of 14,096 patients were included in the ARIAM registry with a diagnosis of UA.

MAIN VARIABLES OF INTEREST

Variables associated with the development of HDAVB, variables associated with the mortality of patients with UA, variables associated with the length of ICU stay of patients with UA.

RESULTS

HDAVB frequency was 1%. Development of HDAVB was independently associated with the Killip classification and the presence of sustained ventricular tachycardia or ventricular fibrillation. Crude mortality of patients was significantly increased when HDAVB was present (9% versus 1%, p < 0,001). When adjusted for other variables, HDAVB was not associated with increased mortality. Development of HDAVB in patients with UA was independently associated with an increase in the length of ICU stay (adjusted odds ratio 1.89: 95% confidence interval: 1.33-5.69).

CONCLUSIONS

Patients with UA complicated with HDAVB represent a high-risk population with an increased ICU stay.

Timing, setting and incidence of cardiovascular complications in patients with acute myocardial infarction submitted to primary percutaneous coronary intervention

BACKGROUND

At the Istituto di Clinica Medica Generale e Cardiologia (Florence, Italy), the widespread use of percutaneous coronary intervention (PCI) has markedly changed the hospital course of patients with acute myocardial infarction (AMI). These patients are typically transferred to the coronary care unit (CCU) only after primary PCI, whereas during the thrombolytic era, patients were first admitted to CCU before reperfusion.

OBJECTIVES AND METHODS

The incidence, timing and setting of complications from symptom onset to hospital discharge in 689 consecutive AMI patients undergoing PCI were evaluated.

RESULTS

Ventricular fibrillation occurred in 11% of patients, and most episodes (94.7%) occurred before or during PCI. Of all patients, 6.3% developed complete atrioventricular block (CAVB), and in 86.3% of these cases, the CAVB occurred before or during PCI; in 94.5%, a CAVB resolution occurred in the catheterization laboratory (CL). Thirty-one patients (4.5%) had impending shock on admission to the CL. Cardiogenic shock developed in 2 9 patients (4.2%), mostly in the prehospital phase or in the CL. Only four patients (less than 1%) developed cardiogenic shock later during their hospital course. Similarly, circulatory and ventilatory support, as well as temporary pacing and cardiac defibrillation, were used mostly in the prehospital phase or in the CL. During the CCU stay, 45 patients (6.5%) had hemorrhagic or vascular complications, and the incidence of post-PCI ischemia and early reocclusion of the culprit vessel were low (2.1% and 0.6%, respectively). Thus, cardiac complications usually associated with AMI were observed mainly before hospital admission or in the CL during the reopening of the target vessel. These complications were rarely observed after a successful PCI.

CONCLUSIONS

For AMI patients, the CL is not only the site of PCI, it is also where most life-threatening cardiac complications are observed and treated.

Patterns of coronary compromise leading to bradyarrhythmias and hypotension in inferior myocardial infarction

BACKGROUND

Occlusion and reperfusion of the acutely occluded right coronary artery may result in abrupt bradycardia and hypotension, attributed to Bezold-Jarisch cardio-inhibitory reflexes arising from the ischemic left ventricle. Given that right ventricular infarction, a result of proximal right coronary artery occlusion, predisposes to bradycardia and hypotension, we hypothesized that proximal right coronary occlusions would be more likely to result in bradycardia-hypotension compared to more distal occlusions.

METHODS

In 216 patients with acute inferior myocardial infarction undergoing primary angioplasty of the right coronary artery, we retrospectively analyzed the incidence of bradyarrhythmias and hypotension during occlusion and with reperfusion.

RESULTS

Occlusion proximal to the right ventricular branches was identified in 151 (70%) of cases, with occlusions distal but compromising the left ventricular and atrioventricular nodal branches in 65 (30%) others. During occlusion, those with proximal occlusions were more likely to suffer hypotension (41 versus 15%, P=0.0002), advanced atrioventricular block (21 versus 3%, P=0.0008) and hypotension with bradycardia (25 versus 9%, P=0.01). Similarly, reperfusion of proximal occlusions more frequently resulted in abrupt hypotension (42 versus 19%, P=0.002), bradycardia (34 versus 14%, P=0.004) and hypotension with bradycardia (27 versus 12%, P=0.02).

CONCLUSIONS

These data demonstrate that during right coronary artery occlusion and with reperfusion, bradycardia and hypotension develop more commonly in patients with proximal occlusions compared with those with distal occlusions. These findings suggest that reflexes arising from the ischemic right ventricle may play a role in bradyarrhythmias and hypotension.

Pulmonary oedema in Swedish hunting dogs

A syndrome of acute dyspnoea after hunting in 16 Swedish hunting dogs is characterised. Radiographic pulmonary infiltrates interpreted as pulmonary oedema were found in the acute stage. In 12 dogs, the infiltrates regressed after five to 14 days. Subendocardial necrosis and pulmonary oedema were found at postmortem examination in four other dogs with acute and recurrent dyspnoea after hunting, and myocardial fibrosis in a further three dogs with a history of recurrent dyspnoea after hunting; none of these pathological changes was seen in dogs which had no previous history of dyspnoea after hunting. A pathogenetic mechanism is proposed whereby high catecholamine levels, present during hunting due to the stress of excitement and exercise, cause acute cardiac and pulmonary lesions in some susceptible dogs, similar to neurogenic or postictal pulmonary oedema.

[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.

Risk stratification after acute myocardial infarction in the reperfusion era

Historically, risk stratification for survivors of acute myocardial infarction (AMI) has centered on 3 principles: assessment of left ventricular function, detection of residual myocardial ischemia, and estimation of the risk for sudden cardiac death. Although these factors still have important prognostic implications for these patients, our ability to predict adverse cardiac events has significantly improved over the last several years. Recent studies have identified powerful predictors of adverse cardiac events available from the patient history, physical examination, initial electrocardiogram, and blood testing early in the evaluation of patients with AMI. Numerous studies performed in patients receiving early reperfusion therapy with either thrombolysis or primary angioplasty have emphasized the importance of a patent infarct related artery for long-term survival. The predictive value of a variety of noninvasive and invasive tests to predict myocardial electrical instability have been under active investigation in patients receiving early reperfusion therapy. The current understanding of the clinically important predictors of clinical outcomes in survivors of AMI is reviewed in this article.

Complete atrioventricular block complicating acute myocardial infarction in the thrombolytic era. SPRINT Study Group and the Israeli Thrombolytic Survey Group. Secondary Prevention Reinfarction Israeli Nifedipine Trial

OBJECTIVES

We assessed the incidence, associated clinical parameters and prognostic significance of complete atrioventricular block (CAVB) complicating acute myocardial infarction (AMI) in the thrombolytic era and compared them to data from the prethrombolytic era.

BACKGROUND

The introduction of new therapeutic modalities to treat AMI, aimed to enhance coronary reperfusion and to limit myocardial necrosis, was expected to decrease the incidence of CAVB and to improve prognosis. However, there are only limited data regarding the incidence and the prognosis of AMI patients with CAVB in the thrombolytic era.

METHODS

Data from 3,300 patients from the Israeli Thrombolytic Surveys (prospective, nationwide surveys of consecutive patients with AMI in all 25 coronary-care units in Israel in 1992 and 1996) were analyzed and compared with data from 5,788 patients included in the SPRINT (Secondary Prevention Reinfarction Israeli Nifedipine Trial) Registry (1981 to 1983).

RESULTS

During the 1990s, the incidence of CAVB was 3.7% compared with 5.3% in the 1980s, p = 0.0007. In the 1990s, mortality of patients with CAVB was significantly higher than in those without CAVB at 7 days (odds ratio [OR] = 4.05 95% CI [confidence interval] 2.34 to 6.82, 30 days OR = 3.98 [95% CI 2.44 to 6.43] and one-year hazard ratio [HR] = 2.36, [95% CI 1.68 to 3.30]) and similar in thrombolysis-treated and not-treated patients. Mortality of patients with CAVB has not changed significantly between the two periods; seven-day OR = 0.82 (95% CI 0.46 to 1.43); 30-day OR = 0.78 (95% CI 0.45 to 1.33) and one-year HR = 0.79 (95% CI 0.54 to 1.56), respectively, in the 1990s as compared to a decade earlier.

CONCLUSIONS

The incidence of CAVB complicating AMI is lower in the thrombolytic era than in the prethrombolytic era. Mortality among patients with CAVB is still high and has not declined within the last decade. The AMI patients who develop CAVB in the thrombolytic era have significantly worse prognosis than do patients without CAVB.

Admission clinical and electrocardiographic characteristics predicting in-hospital development of high-degree atrioventricular block in inferior wall acute myocardial infarction

This study assessed the ability of simple clinical and electrocardiographic variables routinely obtained on admission to identify patients who are at high risk of developing high-degree atrioventricular (AV) block during hospitalization in 1,336 patients with inferior wall acute myocardial infarction (AMI). Patients were classified into 2 initial electrocardiographic patterns based on the J-point to R-wave amplitude ratio: pattern 1: those with J point/R wave <0.5 and pattern 2: patients with J point/R wave > or =0.5 in > or =2 leads of the inferior leads II, III, and aVF. High-degree AV block was found in 6.7% of patients (41 of 615) with pattern 1 versus 11.8% of the patients (85 of 721) with pattern 2 on admission electrocardiogram (p = 0.0008). Multivariate logistic regression analysis revealed that the only variables found to be independently associated with high-degree AV block were female gender (odds ratio [OR] 1.48; 95% confidence interval [CI] 0.98 to 2.23; p = 0.06); Killip class on admission > or =2 (OR 2.24; CI 1.43 to 3.51; p = 0.0004); initial electrocardiographic pattern 2 versus pattern 1 (OR 1.82; CI 1.22 to 2.21; p = 0.003); and absence of abnormal Q waves on admission (OR yes vs no 0.68; CI 0.44 to 1.05; p = 0.08). A simple electrocardiographic sign (J point/R wave > or =0.5 in > or =2 leads) is a reliable predictor of the development of advanced AV block among patients receiving thrombolytic therapy for inferior wall AMI.

Right bundle block in a patient with acute posterior myocardial infarction

We present here a patient with the unusual combination of a newly developed right bundle branch block (RBBB) and an acute posterior myocardial infarction (MI). A dissecting MI with interventricular septal (IVS) rupture was initially thought to have caused RBBB. However, histologic examination revealed that the right bundle branch (RBB) had no ischemic involvement, but did show fibrosis, which suggests that this chronic damage of the RBB was a major contributor to the development of RBBB. This case confirms that the RBB is rarely involved by a posterior MI even in the presence of a dissecting IVS rupture.

Paradoxical shortening of the second PR interval during 3:2 atrioventricular nodal block

A patient with 3:2 second-degree AV block after acute inferior wall myocardial infarction showed consistent PR interval shortening on the second conducted beat in each periodicity. Intracardiac electrophysiologic evaluation revealed that the site of block was nodal. A typical Wenckebach pattern with prolongation of the AH interval was noted. The shorter PR resulted from a paradoxical shortening of the HV interval in the second beat, most likely due to supernormal conduction in the setting of concomitant trifascicular disease.

Temporary Cardiac Pacing in the Intensive Care Unit

Indications for temporary cardiac pacing have increased substantially in the last several years. Although most temporary cardiac pacing is still carried out to treat symptomatic bradycardia due to atrioventricular conduction system disease or atrial bradycardia (i.e., sinus node dysfunction), temporary pacing is currently used to induce and to terminate some supraventricular tachyarrhythmias, prevent pause-dependent ventricular tachycardia (usually torsades de pointes), and vagally mediated atrial fibrillation, to allow the maintenance of hemodynamic competence in postoperative cardiac patients and to evaluate selected patients with hypertrophic and dilated cardiomyopathies who might benefit hemodynamically from cardiac pacing. The roles of transcutaneous and esophageal pacing have also expanded; transcutaneous pacing is now commonly used in patients at high risk for the development of atrioventricular block, such as those with acute myocardial infarction and bifascicular block. We review available types of temporary pacing leads and pulse generators, the methods by which temporary pacing is accomplished, complications of pacing system insertion, and current indications for this therapy. Guidelines for troubleshooting normal and abnormal pacemaker function in the intensive care unit setting are provided.

Alcohol ablation of atrioventricular conduction

Transcoronary ablation of atrioventricular conduction by dehydrated alcohol was attempted in 14 patients with refractory atrial arrhythmias. Alcohol (0.5 or 1.0 ml) was delivered after selective catheterisation of the atrioventricular nodal artery in the 10 patients in whom the artery could be identified by cineangiography. The other four patients underwent electrical ablation when the nodal artery could not be catheterised. Temporary atrioventricular block induced by dilute contrast and cold saline (0.9%) confirmed that the catheter was in the correct position before the alcohol was delivered. In all 10 patients complete atrioventricular block developed after alcohol ablation. The block persisted in all four patients given 1.0 ml alcohol but not in four of the six given 0.5 ml. The mean (SD) creatine kinase (MB fraction) at four to six hours after ablation was 76.5 (49.5) IU after 1.0 ml and 75.5 (43.1) IU after 0.5 ml alcohol (normal less than 20 IU). The overall success rate of alcohol ablation in the whole group on an "intention to treat" basis was 43%. The procedure was a technical success in six of the 10 patients in whom the nodal artery was identified. Transcoronary alcohol ablation of atrioventricular conduction should be considered in patients in whom electrical techniques have been unsuccessful.

Factors associated with late onset of advanced atrioventricular block in acute Q wave inferior infarction

To elucidate the clinical characteristics associated with advanced atrioventricular (AV) block that appears relatively late (more than 24 hours) after the onset of myocardial infarction (MI), 101 patients with acute Q wave inferior MI were studied. Fourteen patients had late-onset advanced AV block, and 87 patients were free of AV block. The hospital mortality rate was 11%. Multivariate analysis was performed to determine the important variables associated with the occurrence of late advanced AV block and hospital mortality rates based on 12 clinical variables. Colloid osmotic pressure, right atrial pressure, serum potassium level, and number of segments with advanced asynergy were the significant factors associated with the occurrence of late advanced AV block, whereas advanced asynergic segments and alveolar arterial oxygen difference were important in the consideration of hospital mortality rates. Therefore not only the extent of myocardial ischemia but also the increases in the extracellular potassium level and interstitial fluid are some of the factors that are associated with the occurrence of late advanced AV block in acute inferior MI. Late advanced AV block, in itself, has no significant influence on hospital mortality rates.

The tall R wave in lead V1 in posterior myocardial infarction: a reciprocal sign or a His-Purkinje conduction disturbance?

The significance of the tall R wave in lead V1 with an R/S ratio greater than or equal to 1 in posterior myocardial infarction (PMI) was investigated in 28 patients during programmed electrical stimulation. The patients had been admitted with acute PMI documented by electrocardiogram and proven by enzymatic increase. Electrophysiological study was performed 3 weeks after acute PMI. In 17 of the 28 patients (group 1), the tall R wave in V1 disappeared during stimulation: In 13 of them a premature atrial extrastimulus was responsible for an abrupt normalization of QRS complex in V1 related to an increase in AH or HV interval. In the 4 remaining patients the disappearance of the tall R wave in V1 was related to a sinus pause. In 14 patients of group 1, a different prematurity in atrial stimulation induced a right or left bundle branch block (BBB). In 11 of the 28 patients (group 2) the tall R wave in V1 was unchanged but a premature atrial extrastimulus induced a right BBB in 5 patients and a left BBB in 6. In conclusion, the normalization of QRS complex in lead V1 during atrial stimulation or alterations in cycle length suggests that the tall R wave in V1 in PMI is not a simple reciprocal sign of leads V8 V9. Its association with different varieties of BBB and changes in AH or HV intervals could suggest a relationship with a His-Purkinje conduction disturbance in some patients.