Stroke distance in acute myocardial infarction: a simple measurement of left ventricular function

Left ventricular outflow tract velocity time integral in hospitalized heart failure with preserved ejection fraction

Aims

The prognostic implication of left ventricular outflow tract velocity time integral (LVOT‐VTI) on admission in hospitalized heart failure with preserved ejection fraction (HFpEF) patients has not been determined. We sought to investigate whether LVOT‐VTI on admission is associated with worse clinical outcomes in hospitalized patients with HFpEF.

Methods and results

We studied consecutive 214 hospitalized HFpEF patients who had accessible LVOT‐VTI data on admission, from a prospective HFpEF‐specific multicentre registry. The primary outcome of interest was the composite of all‐cause death and readmission due to heart failure. During a median follow‐up period of 688 (interquartile range 162–810) days, the primary outcome occurred in 83 patients (39%). The optimal cut‐off value of LVOT‐VTI for the primary outcome estimated by receiver operating characteristic analysis was 15.8 cm. Lower LVOT‐VTI was significantly associated with the primary outcome compared with higher LVOT‐VTI (P = 0.005). Multivariable Cox regression analyses revealed that lower LVOT‐VTI was an independent determinant of the primary outcome (hazard ratio 0.94, 95% confidence interval 0.91–0.98). In multivariable linear regression, haemoglobin level was the strongest independent determinant of LVOT‐VTI among clinical parameters (β coefficient = −0.61, P = 0.007). Furthermore, patients with lower LVOT‐VTI and anaemia had the worst clinical outcomes among the groups (P < 0.001).

Conclusions

Lower admission LVOT‐VTI was an independent determinant of worse clinical outcomes in hospitalized HFpEF patients, indicating that LVOT‐VTI on admission might be useful for categorizing a low‐flow HFpEF phenotype and risk stratification in hospitalized HFpEF patients.

Risk stratification after acute myocardial infarction by Doppler stroke distance measurement

OBJECTIVE

To establish the value of Doppler stroke distance measurement as a predictor of mortality risk following acute myocardial infarction.

DESIGN

Follow up study.

SETTING

Coronary care unit of a teaching and district general hospital.

SUBJECTS

378 patients (mean age 61 years) with acute myocardial infarction followed up for a mean of five years (range 2-7 years); 299 (79%) patients received thrombolysis.

MAIN OUTCOME MEASURES

Stroke distance (the systolic velocity integral of blood flow in the aortic arch (percentage of age predicted normal value)); presence or absence of left ventricular failure on the admission chest radiograph; the codified admission ECG; death during follow up.

RESULTS

Mean (SD) stroke distance was 81 (19)% and five year survival 76%. For patients with stroke distance > 100% (n = 60), 82-100% (n = 134), 63-81% (n = 122), and < 63% (n = 62), the one month mortality rates were 0%, 1.5%, 4%, and 18%, respectively; the corresponding estimates for mortality at five years were 17%, 19%, 24%, and 43%. Survival was independently related to age (p < 0.0001), stroke distance (p < 0.0001), and chest radiograph appearance (p = 0.002), but not to ECG codes (p = 0.31) or receipt of thrombolysis (p = 0.60). The areas under receiver operator characteristic plots for stroke distance measurements were 82%, 76%, 71%, and 65% for deaths within one month, six months, one year, and two years, respectively.

CONCLUSIONS

The bedside measurement of stroke distance stratifies mortality risk after acute myocardial infarction. The predictive ability of this simple measure of left ventricular systolic function compares well with published accounts of the more complex measurement of ejection fraction.

Delay between the onset of symptoms of acute myocardial infarction and seeking medical assistance is influenced by left ventricular function at presentation

OBJECTIVE

To determine whether the interval between the onset of symptoms of acute myocardial infarction and the patient's call for medical assistance (patient delay) is related to left ventricular function at the time of presentation.

DESIGN

Prospective observational study.

SETTING

Coronary care unit of Aberdeen Royal Infirmary.

PATIENTS

93 consecutive patients with acute myocardial infarction.

MAIN OUTCOME MEASURES

Left ventricular stroke distance, expressed as a percentage of the age predicted normal value, measured first on admission, and then daily for 10 days or until discharge. Patients were questioned at admission to determine the time of onset of symptoms and the time of their call for medical assistance.

RESULTS

Median (range) patient delay was 30 (1-360) min. Mean (SD) stroke distance on admission was 70(18)%, rising to 77(19)% on the second recording, and to 84(18)% on the day of discharge. Linear regression of log(e)(patient delay) against first, second, and last measurements of stroke distance gave correlation coefficients of 0.28 (P < 0.01), 0.18 (not significant), and 0.11 (not significant), respectively.

CONCLUSIONS

Patient delay within the first 4 h after the onset of symptoms of acute myocardial infarction is positively related to left ventricular function on admission. A possible explanation is that deteriorating left ventricular function influences the patient's decision to call for help. This tendency for patients with more severe infarction to call for help sooner is an added reason for giving thrombolytic treatment at the first opportunity: those who call early have most to gain from prompt management.

Feasibility, safety, and efficacy of domiciliary thrombolysis by general practitioners: Grampian region early anistreplase trial. GREAT Group

OBJECTIVE

To assess the feasibility, safety, and efficacy of domiciliary thrombolysis by general practitioners.

DESIGN

Randomised double blind parallel group trial of anistreplase 30 units intravenously and placebo given either at home or in hospital.

SETTING

29 rural practices in Grampian admitting patients to teaching hospitals in Aberdeen (average distance 36 (range 16-62) miles).

PATIENTS

311 patients with suspected acute myocardial infarction and no contraindications to thrombolytic therapy seen at home within four hours of onset of symptoms.

MAIN OUTCOME MEASURES

Time saving, adverse events, Q wave infarction, left ventricular function.

RESULTS

Anistreplase was administered at home 101 minutes after onset of symptoms, while anistreplase was given in hospital 240 minutes after onset of symptoms (median times). Adverse events after thrombolysis were infrequent and, apart from cardiac arrest, not a serious problem when they occurred in the community: seven of 13 patients were resuscitated after cardiac arrest out of hospital. By three months after trial entry the relative reduction of deaths from all causes in patients given thrombolytic therapy at home was 49% (13/163 (8.0%) v 23/148 (15.5%); difference -7.6% (95% confidence interval -14.7% to -0.4%), p = 0.04). Full thickness Q wave infarction was less common in patients with confirmed infarction receiving treatment at home (65/122 (53.3%) v 76/112 (67.9%); difference -14.6% (95% confidence interval -27.0% to -2.2%), p = 0.02).

CONCLUSIONS

General practitioners provided rapid pre-hospital coronary care of a high standard. Compared with later administration in hospital, giving anistreplase at home resulted in reduction in mortality, fewer cardiac arrests, fewer Q wave infarcts, and better left ventricular function. Benefits were most marked where thrombolytic therapy was administered within two hours of the onset of symptoms.

Constructing time-specific reference ranges

Reference ranges which take time (such as age) into account are often required in medicine, but simple, systematic and efficient statistical methods for constructing them are lacking. A method is described which is based on low order polynomial curves (linear, quadratic or occasionally cubic), together with guidelines for when and how to apply a logarithmic transformation to the variable analysed, testing for departures from normality, and assessment of the adequacy of the reference range which is constructed from the regression line plus or minus a multiple of the standard deviation. Standard statistical packages may be used to carry out the calculations. The question of comparing two or more groups of patients is addressed. Three examples are discussed in detail.

A comparison of the chronic effects of oral xamoterol and enalapril on blood pressure and renal function in mild to moderate heart failure

1. We compared the effects, after 3 weeks oral therapy, of xamoterol 200 mg twice daily and enalapril 2.5, 5 or 10 mg twice daily on home and clinic blood pressure, glomerular filtration rate (GFR) and renal plasma flow, stroke and minute distances, linear resistance and on plasma renin activity in 19 patients with mild to moderate heart failure in a single-blind randomised crossover study. 2. Enalapril reduced mean home blood pressure by 17/7 mm Hg compared with xamoterol (P less than 0.0001) and by 19/7 mm Hg compared with placebo. Compared with placebo xamoterol had no effect. Enalapril reduced predose blood pressure, compared with xamoterol, on average by 15/5 mm Hg (P = 0.02 systolic, 0.09 diastolic) and by 20/7 mm Hg compared with placebo. At 4 h post-dose the mean differences were: xamoterol-enalapril 13/10 mm Hg (P = 0.01 systolic, 0.0007 diastolic) and placebo-enalapril 23/9 mm Hg. 3. Stroke and minute distances were marginally less 4 h following xamoterol than following enalapril: mean (s.e. mean) values were 9.4 (0.7) vs 10.4 (0.8) cm (P = 0.23) and 699 (51.7) vs 767 (62.1) cm (P = 0.04) respectively. Linear resistance was reduced by enalapril, from the placebo value of 13.2 (1.2) to 11.0 (0.9) mm Hg m-1 and marginally increased by xamoterol, to 14.2 (1.2) mm Hg m-1, the difference between active treatments being statistically significant (P = 0.03). 4. Renal plasma flow, GFR and filtration fraction were not influenced by enalapril or xamoterol therapy. There were no significant correlations between glomerular filtration rate and either blood pressure or stroke distance.(ABSTRACT TRUNCATED AT 250 WORDS)