Signal-to-noise of linear and volume measures of left ventricular and left atrial size.

BACKGROUND: Serial echocardiographic assessments are common in clinical cardiology, e.g., for timing of intervention in mitral and aortic regurgitation. When following patients with serial echocardiograms, each new measurement is a combination of true change and confounding noise. The current investigation compares linear chamber dimensions with volume estimates of chamber size. The aim is to assess which measure is best for serial echocardiograms, when the ideal parameter will be sensitive to change in chamber size and have minimal spurious variation (noise). We present a method that disentangles true change from noise. Linear regression of chamber size against elapsed time gives a slope, being the ability of the method to detect change. Noise is the scatter of individual points away from the trendline, measured as the standard error of the slope. The higher the signal-to-noise ratio (SNR), the more reliably a parameter will distinguish true change from noise. METHODS: LV and LA parasternal dimensions and apical biplane volumes were obtained from serial clinical echocardiogram reports. Change over time was assessed as the slope of the linear regression line, and noise was assessed as the standard error of the regression slope. Signal-to-noise ratio is the slope divided by its standard error. RESULTS: The median number of LV studies was 5 (4-11) for LV over a mean duration of 5.9 ± 3.0 years in 561 patients (diastole) and 386 (systole). The median number of LA studies was 5 (4-11) over a mean duration of 5.3 ± 2.0 years in 137 patients. Linear estimates of LV size had better signal-to-noise than volume estimates (p < 0.001 for diastolic and p = 0.035 for systolic). For the left atrium, the difference was not significant (p = 0.214). This may be due to sample size; the effect size was similar to that for LV systolic size. All three parameters had a numerical value of signal-to-noise that favoured linear dimensions over volumes. CONCLUSION: Linear measures of LV size have better signal-to-noise than volume measures. There was no difference in signal-to-noise between linear and volume measures of LA size, although this may be a Type II error. The use of regression lines may be better than relying on single measurements. Linear dimensions may clarify whether changes in volumes are real or spurious.

Acute papillary muscle infarction and rupture in the puerperium complicating Libman-Sacks endocarditis in a patient with systemic lupus erythematosus and antiphospholipid syndrome: a case report.

BACKGROUND: Acute heart failure caused by severe mitral regurgitation (MR) due to papillary muscle rupture has been described in the puerperium by case reports; however, the majority of cases of papillary muscle rupture are caused by myocardial infarction. We describe papillary muscle rupture occurring in the postpartum period in a patient with systemic lupus erythematosus (SLE), antiphospholipid syndrome (APLS), and chronic Libman-Sacks endocarditis and explore the multifactorial nature of the papillary muscle infarction and rupture in the setting of postpartum fluid shifts, chronic myocardial injury from Libman-Sacks, and high thrombotic risk. CASE SUMMARY: A 29-year-old woman presented with acute heart failure 2 weeks' postpartum and was found to have acute MR due to a flail leaflet caused by papillary muscle rupture. She proceeded to emergency surgery with mitral valve (MV) replacement and the histology revealed evidence of chronic Libman-Sacks endocarditis and papillary muscle infarction with thrombi in the intramyocardial arteries. DISCUSSION: This is the second case report of papillary muscle rupture in the puerperium in a patient with SLE in the literature, the other case was caused by catastrophic APLS. However, in this case, the cause of the rupture is likely to be multifactorial; as a consequence of thrombosis in the microvasculature causing isolated papillary muscle ischaemia, and fibrosis of the muscle due to chronic Libman-Sacks endocarditis resulting in limited pliability which caused rupture of the papillary muscle when faced with the added stress of increased volume that occurs in the puerperium.

Does the early feedback of results improve reassurance following diagnostic testing? A randomized controlled trial in patients undergoing cardiac investigation.

OBJECTIVE: Providing reassurance is often a critical component of the medical consultation. An important area that has not been addressed in the literature is how delay in providing the results of medical tests affects patient reassurance. In this study we investigated whether the early provision of a normal diagnostic result immediately following medical testing improves patient reassurance compared to results provided 4 weeks later. METHOD: We conducted a longitudinal randomized controlled trial and 1-month follow-up. Fifty-one cardiology outpatients with no known cardiac pathology referred for an echocardiogram test were randomized following normal test results to receive their test results from a cardiologist either immediately following testing or 4 weeks later. Measures of symptoms, anxiety, and health perceptions were taken prior to diagnostic testing. Reassurance was assessed immediately after the results were provided and 1 month later. RESULTS: Data analysis showed that the provision of early results had no impact on patient reassurance. Cardiac anxiety was strongly associated with lower reassurance; patients who were more anxious about their heart were significantly less reassured by a normal test result, both immediately following feedback and 1 month later. CONCLUSIONS: The early provision of test results had no impact on patient reassurance. The study suggests the identification and targeting of patients high in cardiac anxiety may be a better method for improving reassurance than reducing the waiting time for results following medical testing.

Advanced Electrocardiography Identifies Left Ventricular Systolic Dysfunction in Non-Ischemic Cardiomyopathy and Tracks Serial Change over Time.

Electrocardiogram (ECG)-based detection of left ventricular systolic dysfunction (LVSD) has poor specificity and positive predictive value, even when including major ECG abnormalities, such as left bundle branch block (LBBB) within the criteria for diagnosis. Although machine-read ECG algorithms do not provide information on LVSD, advanced ECG (A-ECG), using multiparameter scores, has superior diagnostic utility to strictly conventional ECG for identifying various cardiac pathologies, including LVSD. METHODS: We evaluated the diagnostic utility of A-ECG in a case-control study of 40 patients with LVSD (LV ejection fraction < 50% by echocardiography), due to non-ischemic cardiomyopathy (NICM), and 39 other patients without LVSD. Diagnostic sensitivity and specificity for LVSD were determined after applying a previously validated probabilistic A-ECG score for LVSD to stored standard (10 s) clinical 12L ECGs. In 25 of the NICM patients who had serial ECGs and echocardiograms, changes in the A-ECG score versus in echocardiographic LV ejection fraction were also studied to determine the level of agreement between the two tests. RESULTS: Analyses by A-ECG had a sensitivity of 95% for LVSD (93% if excluding N = 11 patients with LBBB) and specificity of 95%. In the 29 NICM patients without LBBB who had serial ECGs, sensitivity improved to 97% when all ECGs were considered. By comparison, human readers in a busy clinical environment had a sensitivity of 90% and specificity of 63%. A-ECG score trajectories demonstrated improvement, deterioration or no change in LVSD, which agreed with echocardiography, in 76% of cases (n = 25). CONCLUSION: A-ECG scoring detects LVSD due to NICM with high sensitivity and specificity. Serial A-ECG score trajectories also represent a method for inexpensively demonstrating changes in LVSD. A-ECG scoring may be of particular value in areas where echocardiography is unavailable, or as a gatekeeper for echocardiography.

Plasma B-type natriuretic peptide levels in cardiac donors.

INTRODUCTION: Elevated levels of plasma brain natriuretic peptide (BNP) and amino-terminal BNP (NT-proBNP) are associated with adverse cardiac outcomes. It is not known whether BNP and NT-proBNP levels in heart donors can aid in selection and predict outcomes in transplant recipients. METHODS: Plasma BNP and NT-proBNP were measured in 32 organ donors prior to removal from life-support systems. Twelve hearts were accepted and 20 hearts were declined (no suitable recipient - 12, probable coronary artery disease - four, abnormal echocardiogram - three, other medical reasons - one). Records of heart transplant recipients were reviewed for: survival at 30 d, length of intensive care stay and need for intra-aortic balloon counter-pulsation (IABP). RESULTS: Donors were divided into three groups - Group 1 (n = 12): accepted hearts; Group 2 (n = 12): acceptable hearts not transplanted for logistic reasons; Group 3 (n = 8): declined because of probable cardiac disease. BNP and NT-proBNP levels were significantly lower in donors with acceptable hearts (n = 24) compared with those with unacceptable hearts (n = 8) (p = 0.02 and 0.032, respectively). Of the 12 patients transplanted, four suffered a suboptimal outcome (two died, one required inotropic support and IABP, one prolonged hospitalization) while eight had good outcomes with no significant difference in BNP/NT-proBNP levels between these groups. CONCLUSION: BNP and NT-proBNP levels were lower in organ donors whose hearts were acceptable for transplantation compared with those whose hearts were unsuitable. Measuring natriuretic peptides may be a useful adjunctive tool in the selection of donor hearts. We feel that further studies are warranted.