Interobserver agreement and accuracy of bedside estimation of right and left ventricular ejection fraction in acute myocardial infarction

Reliability of estimating left ventricular ejection fraction in clinical routine: a validation study of the SWEDEHEART registry

OBJECTIVE

Patients hospitalized with acute coronary syndrome (ACS) in Sweden routinely undergo an echocardiographic examination with assessment of left ventricular ejection fraction (LVEF). LVEF is a measurement widely used for outcome prediction and treatment guidance. The obtained LVEF is categorized as normal (> 50%) or mildly, moderately, or severely impaired (40-49, 30-39, and < 30%, respectively) and reported to the nationwide registry for ACS (SWEDEHEART). The purpose of this study was to determine the reliability of the reported LVEF values by validating them against an independent re-evaluation of LVEF.

METHODS

A random sample of 130 patients from three hospitals were included. LVEF re-evaluation was performed by two independent reviewers using the modified biplane Simpson method and their mean LVEF was compared to the LVEF reported to SWEDEHEART. Agreement between reported and re-evaluated LVEF was assessed using Gwet's AC2 statistics.

RESULTS

Analysis showed good agreement between reported and re-evaluated LVEF (AC2: 0.76 [95% CI 0.69-0.84]). The LVEF re-evaluations were in agreement with the registry reported LVEF categorization in 86 (66.0%) of the cases. In 33 (25.4%) of the cases the SWEDEHEART-reported LVEF was lower than re-evaluated LVEF. The opposite relation was found in 11 (8.5%) of the cases (p < 0.005).

CONCLUSION

Independent validation of SWEDEHEART-reported LVEF shows an overall good agreement with the re-evaluated LVEF. However, a tendency towards underestimation of LVEF was observed, with the largest discrepancy between re-evaluated LVEF and registry LVEF in subjects with subnormal LV-function in whom the reported assessment of LVEF should be interpreted more cautiously.

Comparison of effectiveness of hand-carried ultrasound to bedside cardiovascular physical examination

This study compared the accuracy of cardiovascular diagnoses by medical students operating a small hand-carried ultrasound (HCU) device with that of board-certified cardiologists using standard physical examinations. Sixty-one patients (38% women; mean age 70 +/- 19 years) with clinically significant cardiac disease had HCU studies performed by 1 of 2 medical students with 18 hours of training in cardiac ultrasound and physical examinations by 1 of 5 cardiologists. Diagnostic accuracy was determined by standard echocardiography. Two-hundred thirty-nine abnormal findings were detected by standard echocardiography. The students correctly identified 75% (180 of 239) of the pathologies, whereas cardiologists found 49% (116 of 239) (p <0.001). The students' diagnostic specificity of 87% was also greater than cardiologists' specificity of 76% (p <0.001). For nonvalvular pathologies (115 findings), students' sensitivity was 61%, compared with 47% for cardiologists (p = 0.040). There were 124 clinically significant valvular lesions (111 regurgitations, 13 stenoses). Students' and cardiologists' sensitivities for recognizing lesions that cause a systolic murmur were 93% and 62% (p <0.001), respectively. Students' sensitivity for diagnosing lesions that produce a diastolic murmur was 75%; cardiologists recognized 16% of these lesions (p <0.001). The diagnostic accuracy of medical students using an HCU device after brief echocardiographic training to detect valvular disease, left ventricular dysfunction, enlargement, and hypertrophy was superior to that of experienced cardiologists performing cardiac physical examinations.

Beauty is in the eye of the examiner: reaching agreement about physical signs and their value

Despite advances in other areas, evidence-based medicine is yet to make substantial inroads on the standard medical physical examination. We have reviewed the evidence about the accuracy and reliability of the physical examination and common clinical signs. The physical examination includes many signs of marginal accuracy and reproducibility. These may not be appreciated by clinicians and could adversely affect decisions about treatment and investigations or the teaching and examination of students and doctors-in-training. We provide a selected summary of the reliability and accuracy as well as important messages of key findings in the physical examination.

In-hospital heart failure, first-year ventricular dilatation and 10-year survival after acute myocardial infarction

BACKGROUND

Little is known about the factors that determine long-term prognosis in patients who have survived the first year after acute myocardial infarction (AMI).

AIMS

To study the influence of left and right ventricular (LV and RV) dilatation during the first year after AMI on subsequent 10-year survival in comparison with in-hospital heart failure and other established prognostic indices.

METHODS

Radionuclide ventriculography was performed before the era of thrombolysis and post-infarction ACE-inhibition in 57 patients with AMI at hospital discharge and again 1 year later, and compared with survival the ensuing 10 years.

RESULTS

After 1 year significant LV-dilatation (>20%) had occurred in 32 (56%) patients. One year after the re-investigation the mortality in these was 19% vs. 0% in patients without dilatation (P=0.02); after 5 years the difference was 38 vs. 12% (P=0.02), whereafter it declined and became insignificant at 10 years. Neither RV-dilatation, nor LVEF determined at discharge or at the 1-year reinvestigation influenced long-term survival. In contrast, clinical heart failure recorded during the hospital stay had a sustained negative influence on long-term survival.

CONCLUSION

Progressive LV dilatation after discharge and clinical heart failure during the hospital stay are both determinants of late survival after AMI, whereas LV ejection fraction at hospital discharge or 1 year later has little, if any, effect on survival beyond 1-year post-AMI.

How well can the chest radiograph diagnose left ventricular dysfunction?

OBJECTIVES

To review the diagnostic utility of the chest radiograph for left ventricular dysfunction.

DATA SOURCES

Structured MEDLINE searches, citation reviews of relevant primary research, review articles, and textbooks, personal files, and data from experts.

STUDY SELECTION

Studies of patients without valvular disease that allowed calculation of the sensitivity and specificity of selected radiographic signs compared with a criterion standard of increased left ventricular preload or reduced ejection fraction.

DATA EXTRACTION

Two independent readers reviewed 29 studies. Studies were pooled after stratification by radiographic finding, criterion standard, and clinical setting.

MAIN RESULTS

Redistribution best diagnosed increased preload with a sensitivity of 65% (95% confidence interval [CI] 55%, 75%) and specificity 67% (95% CI 53%, 79%). Cardiomegaly best diagnosed decreased ejection fraction with a sensitivity of of 51% (95% CI 43%, 60%) and specificity of 79% (95% CI 71%, 85%). Interrater reliability was fair to moderate for redistribution and moderate for cardiomegaly. The clinical setting affected results by decreasing the specificity of cardiomegaly to 8% in detecting increased preload in patients with severe systolic dysfunction. The absence of redistribution could only exclude increased preload in situations in which the suspicion (pretest probability) of disease was less than 9%, whereas redistribution could confirm increased preload when the pretest probability was greater than 91%. The absence of cardiomegaly could only exclude a reduced ejection fraction if the pretest probability was less than 8%, whereas cardiomegaly could confirm a reduced ejection fraction if the pretest probability was greater than 87%.

CONCLUSIONS

Redistribution and cardiomegaly are the best chest radiographic findings for diagnosing increased preload and reduced ejection fraction, respectively. Unfortunately, neither finding alone can adequately exclude or confirm left ventricular dysfunction in usual clinical settings. Redistribution is not always reliably interpreted.

Accuracy and reliability of apical S3 gallop detection

This study assessed physician performance in detecting the apical S3 gallop using a cardiology patient simulator. Six physicians (two cardiology fellows, two medicine residents, and two attending physicians) performed two sets of 24 cardiac examinations that included the presence or absence of an apical S3 gallop. All the examiners were able to significantly alter the prior odds of an apical S3 gallop's being present, but the cardiology fellows had higher sensitivities. Sensitivity was lower for detecting soft S3 gallops, and specificity was lower when a diastolic murmur was also present. Physician performance in detecting apical S3 gallops is variable, but can be excellent.

Making judgements about treatment effectiveness based on health outcomes: theoretical and practical issues

ISSUES

This article considers the problem of deciding which health care outcomes are important and relevant for (1) developing management recommendations for clinical practice guidelines and (2) evaluating patients' responses to treatment.

DECISIONS

The Heart Failure Guideline Panel sponsored by the Agency for Health Care Policy and Research (AHCPR) decided that for both purposes the relevant outcomes are those experienced directly by patients: mortality and health-related quality of life (HRQOL). Changes in intermediate outcomes, such as test results of various kinds, were deemed insufficient evidence of effectiveness.

CONCLUSIONS

In the context of heart failure, mortality risk (prognosis) can be measured using a variety of biochemical and physiological variables, but changes in these variables do not appear to correspond to changes in prognosis. For this reason, the Heart Failure Guideline Panel recommended that patients' responses to treatment be guided by signs and symptoms, rather than test results (for example, echocardiographic measurement of left-ventricular function or exercise-tolerance testing). HRQOL is best assessed by direct patient self-reports. Although patients may be influenced by a host of other variables (for example, mood, adaptation to chronic disease, placebo effect), self-reports will probably always represent the "gold standard" in assessing HRQOL. The reliability and validity of these reports can be enhanced by using standardized instruments or by incorporating questions from such instruments into the history-taking aspect of patient evaluation and monitoring. Finally, physical examination and submaximal exercise testing can provide additional information that can supplement patient reports. Information from these sources must be evaluated carefully in light of patients' self-reported HRQOL.

Sensitivity and specificity of echocardiographic identification of patients eligible for safe early discharge after acute myocardial infarction

In a prospective clinical trial of 195 consecutive unselected patients with acute myocardial infarction (AMI), systematic blinded clinical and echocardiographic examinations were performed by two observers on day 5. The purpose was to define low-risk patients with regard to in-hospital and 2-month mortality and predict the potential costs (lost patient lives) and benefits (saved in-patient days) if as a routine procedure these low-risk patients were discharged earlier. By design, low-risk patients as defined by clinical criteria were allocated to discharge on days 7 to 10 and by echocardiographic criteria on days 5 to 7 after AMI. The sensitivity of the echocardiographic low-risk identification procedure was more than twofold higher than the sensitivity of clinical low-risk identification (49% vs 24%). Both procedures were safe with a specificity of 100% for cardiac mortality. Optimal identification of low-risk patients was provided by combining data from echocardiographic and clinical evaluations (sensitivity 59%). Results of the study suggest that a bedside echocardiographic approach to estimation of global left ventricular function is more sensitive and equally specific and therefore more efficient for risk stratification on post-AMI day 5 than clinical examination alone. Thus echocardiographic examination allows identification of a larger subset of patients with AMI (greater than 40% of the population alive on day 5) who can be discharged earlier and safely, with a potential saving of in-patient days of 436 days in 87 low-risk patients minus the cost of echocardiographic studies in 195 patients. However, the best prediction was obtained by combining clinical and echocardiographic examination.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiographic algorithms for admission and predischarge prediction of mortality in acute myocardial infarction

To develop improved prognostic algorithms for routine bedside use in acute myocardial infarction (AMI), the prognostic value concerning 2- and 12-month mortality of an early (within 72 hours after AMI) resting echocardiogram was defined in 201 consecutive patients. The relation between (1) the clinical variables (age, sex, prior and repeat AMI, arrhythmias, cardiac arrest, early [less than 72 hours after AMI] and late heart failure, early and maximal in-hospital Killip class, and maximal creatine kinase-MB isoenzyme), (2) early myocardial performance by echocardiography, and (3) mortality was characterized by Kaplan-Meier survival curves and receiver-operating characteristic curves based on Cox regression model. Only age and clinical heart failure in terms of the maximal in-hospital Killip class had independent predictive value of death (p less than 0.05) when an early echocardiographic estimate of left ventricular ejection fraction (LVEF) was included in the multivariate statistical models. The following 2 optimized algorithms for admission and predischarge calculation of risk of mortality at 2 and 12 months were developed based on the Cox model, using combinations of age, maximal Killip class and early echocardiographic LVEF: mortality at 2 months = 1 - exp - [0.051 x exp [0.044 x (age -60) - (0.117 x (LVEF - 40)]]; and mortality at 1 year = 1 - exp - [0.101 x exp [0.408 x (maxKillip - 1) - (0.061 x (LVEF - 40)]]. Discriminative power for prediction of mortality of the predischarge algorithm in an independent population of 195 patients 5 days after AMI compared favorably with that obtained in the original population, confirming the validity of the proposed method of prognostication.

Bedside diagnosis of preserved versus impaired left ventricular systolic function in heart failure

The importance of recognizing symptomatic heart failure with preserved left ventricular (LV) systolic function has only recently been appreciated. To determine its frequency and identify clinical features that make the bedside diagnosis likely, 82 patients admitted for decompensated heart failure were classified into 2 groups based on their LV systolic performance, as defined by fractional shortening (FS): group I (n = 59), with impaired systolic function (fractional shortening less than 24%), and group II (n = 23) with preserved systolic function (fractional shortening greater than or equal to 24%). Mean fractional shortening was 15 +/- 5% and 39 +/- 1% for groups I and II, respectively. Female gender (p less than 0.05), obesity (p less than 0.01) and diastolic blood pressure greater than or equal to 105 mm Hg (p less than 0.05) predominated in group II. Jugular venous distention was identified more frequently in group I (p less than 0.05). No statistically significant difference between the 2 groups was noted among various demographic variables (age, duration of symptoms, history of hypertension, ischemic heart disease and heavy alcohol drinking) or physical findings (S3 gallop, edema, cardiomegaly, pulmonary congestion and pulmonary edema). Echocardiographic mean left ventricular dimension measured 6.6 +/- 1 versus 5.0 +/- 1 cm (p less than 0.01) and mean posterior wall thickness 1.1 +/- 0.3 versus 1.4 +/- 0.4 cm (p less than 0.01) in group I and II, respectively. The combination of diastolic blood pressure greater than or equal to 105 mm Hg and an absence of jugular venous distention had a high specificity and positive predictive value (100%) for identifying group II patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Early estimation of risk by echocardiographic determination of wall motion index in an unselected population with acute myocardial infarction

In a prospective series of 201 consecutive patients with creatine kinase-MB--documented acute myocardial infarction (AMI), postadmittance and predischarge echocardiographic wall motion indexes (WMI) were determined (median 45 hours vs 14 days after AMI). No significant change of left ventricular systolic performance was found between postadmittance and predischarge examinations in 179 survivors (WMI 1.3 +/- 0.4 vs 1.4 +/- 0.4, p greater than 0.05). Hospital mortality was 11% (22 of 201), cumulated 2-month mortality 15% (31 of 201) and cumulated 1-year mortality 26% (52 of 201). Mortality increased rapidly with decreasing left ventricular function as determined by WMI. When early WMI was less than 1.0, 1-year mortality was 51% (28 of 55) versus 8% (7 of 83) when WMI was greater than 1.3 (p less than 0.0001). Ventricular fibrillation (n = 24) and cardiogenic shock (n = 27) carried a much better prognosis when WMI showed good left ventricular function. When WMI was less than 1.0, 1-year mortality was 83% (10 of 12) versus 93% (13 of 14) in ventricular fibrillation and cardiogenic shock, respectively, whereas it was 0% (0 of 4) versus 33% (2 of 6) when WMI was greater than 1.3. In 15% of patients major discrepancies between early Killip class and WMI were noted. WMI showed much smaller fluctuations during the hospital course of AMI than did Killip class and appeared to be a more stable prognostic marker. Large-scale, early risk stratification by echocardiography has now become available and appears to facilitate a rational, individualized discharge policy in the coronary care unit and to provide an improved basis for randomization of patients in controlled studies aimed at tailoring new treatment in AMI.

Late ventricular dilatation in survivors of acute myocardial infarction

The purpose of this study was to assess the natural course of left ventricular (LV) volumes in the convalescent phase of acute myocardial infarction (AMI). Fifty-seven patients were examined 2 weeks and approximately 1 year after AMI by a radionuclide method allowing determination of absolute LV volumes. After 1 year the patients had fewer clinical and radiologic signs of heart failure, but median end-diastolic volume index had increased from 92 to 112 ml/m2 (p less than 0.001), median end-systolic volume index from 51 to 65 ml/m2 (p less than 0.001) and median stroke volume index from 39 to 47 ml/m2 (p less than 0.001). Patients with first anterior infarcts had significantly greater increases in end-diastolic volume index, end-systolic volume index and stroke volume index than patients with first inferoposterior infarcts. The increase in LV volumes was significantly greater in patients with clinical manifestations of heart failure than in those without these signs. Notably, changes in LV size had an unpredictable effect on LV ejection fraction.