10-year experience with the surgical treatment of ventricular tachycardia following acute myocardial infarction

From 1980 to 1988 direct arrhythmia surgery was performed in 121 patients suffering from postinfarction drug-refractory ventricular tachycardia (VT). By 1986 the initially high in-hospital mortality of 26% (18 of 69 patients) had decreased to 1.9% (1 of 52 patients). The 3-year actuarial survival of patients operated since 1986 is 90%. From 1985 the results of surgical therapy of VT have improved: 86% of the patients remained arrhythmia-free without drugs; none died suddenly. Residual left ventricular function was related to the prognosis, but the interval between the last myocardial infarction and time of surgery or the surgical technique were not. These results demonstrate that direct surgery has become a valuable method in the treatment of postinfarction VT, at least in patients with sufficient residual left ventricular function.     

A model of prehospital death from ventricular fibrillation following myocardial infarction.

Current efforts to reduce prehospital cardiac mortality focus more on deployment of specially equipped ambulances than on reduction of patient or ambulance delays. To evaluate this strategy, we needed to find a method that would isolate the separate effects of patient delay, ambulance delay, and the resuscitative capability of the ambulance. Using published data, we have generated a mathematical model of death from ventricular fibrillation following myocardial infarction that shows the relationship among these three factors. Analyses based on the model indicate that the potential life saving impact of a defibrillation-equipped ambulance is severely limited due to typical patient response patterns. If the ambulance arrives ten minutes after the onset of infarction, defibrillation capabilities will reduce prehospital mortality from 6 percent to 2 percent. After a more typical delay of 60 minutes, the mortality rises sharply to 13 percent for an unequipped ambulance. With a delay of this length, defibrillation capabilities reduce mortality only to about 12 percent.     

Analysis of premature ventricular counts in long term ECG following myocardial infarction.

Frequent and recurrent ventricular premature beats (VPB's) are considered to be associated with a higher risk of sudden cardiac death, particularly for survivors of myocardial infarction (MI). The distribution of VPB's has a large probability mass at zero, and a very heavy right hand tail. In this research, we fitted a model to VPB for patients for which VPB was present. The model was fitted on the basis of a relatively large data set on MI survivors in Israel. The model was fitted by a method which is based on the generalized linear model. This method, which was introduced by Zeger and Liang, is designed for longitudinal data and uses the quasi-likelihood concept. No specific assumptions are required on the shape of the distribution of the dependent variable. The results indicate that the model fits the data quite well but underestimates the very extreme high values. This research demonstrates the applicability of generalized linear models for longitudinal non-Gaussian data. Such data often arise in medical studies. The study also points out the distributional properties of VPB counts. In particular, it shows their associations with simple clinical and epidemiological variables, and with certain time periods during the day.     

急性心肌梗死心电图对梗塞相关动脉的预测价值

目的探讨急性心肌梗死患者体表心电图对梗塞相关动脉预测的价值.方法对120例急性心肌梗死患者的心电图与冠脉造影结果进行比较.结果前间壁、前壁、广泛前壁心肌梗死其左前降支病变阳性率96.6%;下壁心肌梗死其右冠脉病变阳性率83%,左回旋支病变阳性率60%;下后壁心肌梗死其右冠脉病变阳性率89%,左回旋支病变阳性率67%;右室梗死其右冠脉病变阳性率100%;下壁合并右室梗死其右冠脉病变阳性率88%;正后壁梗死3例均显示为三支病变.结论心肌梗死心电图定位与其相关冠脉病变关系密切,虽然有一定的局限性,仍不失为一项重要的评估方法.     

In-hospital prognosis of right ventricular myocardial infarction

AIM: To identify prognostic risk factors for in-hospital outcome of right ventricular myocardial infarction (RVI). METHODS: A retrospective study of 20 patients admitted with acute myocardial infarction with a RVI defined by ST segment elevation > or = 1 mm in V3R and V4R leads. RESULTS: The mean age was 62 years. RVI was associated with an inferior myocardial infarction in 18 patients. Half of the patients had hemodynamic complication on admission (cardiogenic shock in 4 cases, right ventricular failure in 6 cases) and third degree atrio-ventricular block was present in 5 patients. Sixteen patients (80%) received thrombolysis and 3 went to an emergency angioplasty. The in-hospital mortality was 25% caused by a cardiogenic shock in 4 patients and a ventricular fibrillation in 1 patient. Statistic analysis showed that cardiogenic shock on admission, the absence of thrombolytic therapy and the low ejection fraction of the left ventricle were associated with a high in-hospital mortality (p = 0.004, p = 0.03, p = 0.03 respectively). CONCLUSION: In-hospital outcome of RVI is characterized by hemodynamic complications leading to a high incidence of mortality. Thus RVI must be diagnosed quickly and maximal therapeutic efforts must be done to procure the opening of the occluded coronary artery.     

急性心肌梗死直接PTCA术后1小时ST段变化对近期预后的评估

目的　探讨急性心肌梗死直接PTCA术后1hST段变化对急性期预后的评估意义。方法　观察接受直接PTCA的病人5 0例。比较入院时心电图抬高的ST段和术后1h抬高的ST段。按抬高的ST段下移>5 0 %或<5 0 % ,分为A组(2 9例)和B组(2 1例)。对比其急性期临床资料和心功能情况。结果　B组病人住院期间、易出现急性左心衰、射血分数较低。结论　急性心肌梗死直接PTCA术后1hST段变化,反映心肌再灌注治疗后的微循环情况,是预测早期临床预后和检出高危患者的简便而可靠的方法。     

Diagnostic criteria for hospitalized acute myocardial infarction: the Minnesota experience

Standardized diagnostic algorithms are needed for systematic surveillance of hospitalized acute myocardial infarction (AMI). Ambiguities in diagnostic classification are resolvable to the extent that objective information is available in the hospital chart. In this study of diagnostic algorithms, serum cardiac enzyme levels, especially creatine kinase total (CK-TOT) and creatine kinase myocardial band (CK-MB) isoenzyme, were most closely correlated with the physician-reviewer diagnostic assignment used for validation; chest pain and electrocardiographic findings were less closely correlated. In addition, a close relationship was noted between the clinician's diagnostic impression and testing procedures and the final hospital discharge diagnosis. Thus, the algorithm should include discharge diagnosis as a classification element. The algorithm for cases discharged as acute myocardial infarction should be very sensitive, tending to call cases acute myocardial infarction. Other discharge diagnoses may harbour some clinically unrecognized myocardial infarction cases; however, the algorithm for such cases should be restrictive and specific to minimize false positives. These findings indicate optimal ways of combining clinical characteristics to most completely and accurately identify cases of acute myocardial infarction based on hospital records examined in retrospect.     

The value of myocardial perfusion scintigraphy in the diagnosis and management of angina and myocardial infarction: a probabilistic economic analysis.

BACKGROUND AND AIM: Coronary heart disease (CHD) is the most common cause of death in the United Kingdom, accounting for more than 120,000 deaths in 2001, among the highest rates in the world. This study reports an economic evaluation of single photon emission computed tomography myocardial perfusion scintigraphy (SPECT) for the diagnosis and management of coronary artery disease (CAD). METHODS: Strategies involving SPECT with and without stress electrocardiography (ECG) and coronary angiography (CA) were compared to diagnostic strategies not involving SPECT. The diagnosis decision was modeled with a decision tree model and long-term costs and consequences using a Markov model. Data to populate the models were obtained from a series of systematic reviews. Unlike earlier evaluations, a probabilistic analysis was included to assess the statistical imprecision of the results. The results are presented in terms of incremental cost per quality-adjusted life year (QALY). RESULTS: At prevalence levels of CAD of 10.5%, SPECT-based strategies are cost-effective; ECG-CA is highly unlikely to be optimal. At a ceiling ratio of Pound 20,000 per QALY, SPECT-CA has a 90% likelihood of being optimal. Beyond this threshold, this strategy becomes less likely to be cost-effective. At more than Pound 75,000 per QALY, coronary angiography is most likely to be optimal. For higher levels of prevalence (around 50%) and more than a Pound 10,000 per QALY threshold, coronary angiography is the optimal decision. CONCLUSIONS: SPECT-based strategies are likely to be cost-effective when risk of CAD is modest (10.5%). Sensitivity analyses show these strategies dominated non-SPECT-based strategies for risk of CAD up to 4%. At higher levels of prevalence, invasive strategies may become worthwhile. Finally, sensitivity analyses show stress echocardiography as a potentially cost-effective option, and further research to assess the relative cost-effectiveness of echocardiography should also be performed.     

The prognostic value of the duration of the ambulatory electrocardiogram after myocardial infarction

The purpose of this study was to examine the value of various durations of ambulatory ECG recording with regard to providing useful prognostic information. The authors explored a decision theoretic approach to determine the most useful period of monitoring for making a treatment decision based upon postulated benefit-to-risk ratios of antiarrhythmic therapies. They used data collected as part of the Beta-Blocker Heart Attack Trial (BHAT), a randomized clinical trial of propranolol versus placebo in 3,837 post-myocardial-infarction patients. In BHAT, 1,336 placebo-treated patients had a 24-hour ambulatory ECG that had at least 23 readable hours. Sensitivity and specificity were calculated for eight definitions of ventricular arrhythmia using either total mortality or sudden death (death within one hour of symptoms) as an endpoint. These indices were obtained using the first 1, 2, 4, 6, 12, and 24 hours plus a random hour, a random daytime hour, and a random nighttime hour of the 24-hour ECG of 1,336 placebo-treated patients. The study showed that in the case of high-risk, low-benefit therapies, no test is needed to make a treatment decision. No one should be treated. In the case of high-benefit, low-risk therapies, again, no test is required. Everyone should be treated. For therapies in the middle benefit-to-risk ratio range the most appropriate test for a treatment decision changes from the very specific to the most sensitive. Twenty-four hours of ambulatory monitoring is usually not necessary for a treatment decision, since four hours is likely to be sufficient.