ANP and BNP in atrial fibrillation before and after cardioversion--and their relationship to cardiac volume and function.

The role of atrial (ANP) and B-type (BNP) natriuretic peptide in atrial fibrillation (AF) is not clear. Our aim was to describe ANP and BNP in AF, and their changes following cardioversion in persistent AF. Furthermore, we wanted to assess the association between ANP and BNP and cardiac volume and function evaluated by magnetic resonance imaging. ANP and BNP decreased significantly following cardioversion. After 180 days of sinus rhythm, ANP and BNP were still significantly elevated. Same results were seen in patients with lone AF. Left and right atrial volumes correlated positively with ANP and BNP. Changes in left atrial volume were predictive of changes in ANP and BNP following cardioversion. AF may cause enduringly elevated ANP and BNP and atrial volume seems to be an important determinant of ANP and BNP in AF.

ST-segment deviation analysis of the admission 12-lead electrocardiogram as an aid to early diagnosis of acute myocardial infarction with a cardiac magnetic resonance imaging gold standard.

OBJECTIVES: The purpose of this study was to validate existing 12-lead electrocardiographic (ECG) ST-segment elevation myocardial infarction (STEMI) criteria in the diagnosis of acute myocardial infarction (AMI) and the application of similar ST-segment depression (STEMI-equivalent) criteria with contrast-enhanced cardiac magnetic resonance imaging (ceMRI) as the diagnostic gold standard. BACKGROUND: The admission ECG is the cornerstone in the diagnosis of AMI, and ceMRI is a new diagnostic gold standard that can be used to validate existing and novel 12-lead ECG criteria. METHODS: One hundred fifty-one consecutive patients with their first hospital admission for chest pain underwent ceMRI. The 116 patients without ECG confounding factors were included in this study, and AMI was confirmed in 58 (50%). The admission ECG was evaluated on the basis of the lead distribution of ST-segment deviation according to current American College of Cardiology/European Society of Cardiology (ACC/ESC) guidelines. RESULTS: A sensitivity of 50% and specificity of 97% for AMI were achieved with the currently applied ST-segment elevation criteria. Consideration of ST-segment depression in addition to elevation increased sensitivity for detection of AMI from 50% to 84% (p < 0.0001) but only decreased specificity from 97% to 93% (p = 0.50). There were no significant differences in AMI location or size between patients meeting the 12-lead ACC/ESC ST-segment elevation criteria and those only meeting the ST-segment depression criteria. CONCLUSIONS: In patients admitted to hospital with possible AMI, the consideration of both ST-segment elevation and depression in the standard 12 lead-ECG recording significantly increases the sensitivity for the detection of AMI with only a slight decrease in the specificity.

Atrial and ventricular volume and function evaluated by magnetic resonance imaging in patients with persistent atrial fibrillation before and after cardioversion.

Atrial fibrillation (AF) is the most common cardiac arrhythmia and 25% of those >40 years old will experience AF. Left atrial size and left ventricular function are independently related to cardiovascular morbidity and mortality. Our aim was to evaluate cardiac volume and function using magnetic resonance imaging in patients with persistent AF and to describe the changes after cardioversion (CV). Sixty consecutive patients with persistent AF and 19 healthy volunteers had cardiac volumes evaluated by cinematographic breath-hold magnetic resonance imaging. Patients with AF were evaluated before CV and at 1, 30, and 180 days after CV, if still in sinus rhythm. All atrial and ventricular volumes and left ventricular mass decreased and ejection fractions increased significantly after CV (p <0.0001 for all variables). Atrial and ventricular diastolic volumes increased significantly the day after CV. The atrial diastolic volumes had decreased significantly at 30 days and ventricular volumes at 180 days. The atrial systolic volumes decreased significantly the day after CV, but the ventricular systolic volumes remained constant the day after CV and decreased thereafter. Only the right atrial volumes were normalized 180 days after CV. The same results were found in a subgroup of patients with lone AF. In conclusion, reversal of atrial dimensions and function happened earlier than ventricular reversal after CV in persistent AF. Atrial reversal began immediately and ventricular reversal was not seen before 30 days after CV. Our results suggest that the changes to the left atrium and both ventricles caused by AF could be permanent and that CV of AF may be preferable.

The relationship between electrical axis by 12-lead electrocardiogram and anatomical axis of the heart by cardiac magnetic resonance in healthy subjects.

BACKGROUND: The traditional assumption has been that there is a close relationship between the electrical and anatomical axes of the heart. The aim of this study was to test the hypothesis that there is a correlation between the electrical and anatomical axes of the heart, in both the frontal and transverse planes, in healthy subjects. METHODS: Ninety-four healthy volunteers (48 men, 46 women; age 21-82 years) were studied by cardiac magnetic resonance and 12-lead electrocardiogram. The anatomical axis was determined by cardiac magnetic resonance and projected onto the frontal and transverse orthogonal planes for comparison with the electrical axis in the corresponding planes. RESULTS: The electrical and anatomical axes were in the same range in the frontal plane (mean +/- SD, +39 degrees +/- 31 degrees and +38 degrees +/- 10 degrees), but in different ranges in the transverse plane (mean +/- SD, -30 degrees +/- 18 degrees and +46 degrees +/- 7 degrees). The partial correlation coefficients between electrical and anatomical axes were r = 0.30 (P < .01) and r = 0.14 (P = NS) in the frontal and transverse planes, respectively. Age was more strongly correlated to electrical axis than to anatomical axis in the frontal plane. CONCLUSIONS: There is only a weak correlation between electrical and anatomical axes in the frontal plane and no correlation in the transverse plane. The change of electrical axis with increased age is not explained only by change in the anatomical axis. The results suggest that there is no simple relationship between the electrical and anatomical axes of the heart.

Determination of left ventricular long-axis orientation using MRI: changes during the respiratory and cardiac cycles in normal and diseased subjects.

BACKGROUND: It has previously been shown that magnetic resonance imaging (MRI) can be used to accurately determine left ventricular (LV) long-axis orientation in healthy individuals. However, the inter- and intra-observer variability in patients with acute coronary syndrome (ACS) and chronic heart failure (CHF) has not been explored. Furthermore, the changes in LV long-axis orientation because of respiration and during the cardiac cycle remain to be determined. METHODS: LV long-axis orientation was determined by MRI in the frontal and transverse planes in 44 subjects with no cardiac disease, 20 ACS patients and 13 CHF patients. Changes in LV long-axis orientation because of respiration were assessed in a subset of 25 subjects. Changes during the cardiac cycle were assessed in six subjects from each subject group. Reproducibility was assessed by a re-examination of 17 subjects after 28 days. RESULTS: The inter- and intra-observer variability for LV long-axis orientation was low for all subject groups. The difference between the baseline and the 28 days examinations was -1.4+/-5.9 degrees and -0.8+/-4.4 degrees in the frontal and transverse planes, respectively. No significant change in LV long-axis orientation was found between end-expiration and end-inspiration (frontal plane, P=0.63 and transverse plane, P=0.42; n=25). No significant difference in change of the LV long-axis orientation during the cardiac cycle was found between the subject groups (frontal plane, chi-square 1.8, P=0.40 and transverse plane, chi-square 5.7, P=0.06). CONCLUSIONS: There is a low inter-and intra-observer variability and a high reproducibility for determining LV long-axis orientation in patients with no cardiac disease as well as in patients with ACS or CHF. There is no significant change in LV long-axis orientation due to respiration, and only small changes during the cardiac cycle in these groups.

Contrast enhanced-cardiovascular magnetic resonance imaging in patients with pulmonary hypertension.

AIMS: To determine the presence and extent of delayed contrast enhancement (DCE) in patients with pulmonary hypertension (PHT) using contrast enhanced-cardiovascular magnetic resonance imaging (ce-CMR). METHODS AND RESULTS: Twenty-five patients with PHT underwent ce-CMR and right heart catheterization. Right ventricular (RV) and left ventricular (LV) volumes, ejection fraction, mass, and DCE mass were determined with ce-CMR. Mean pulmonary artery pressure (mean PAP) averaged 43 (12) mmHg and cardiac output 4.3 (1.2) L/min. DCE was demonstrated in 23 out of 25 patients. DCE was confined to the RV insertion points (RVIPs) in seven patients and extended into the interventricular septum (IVS) in the remaining 16 patients. In these 16 patients, septal contrast enhancement was associated with IVS bowing. The extent of contrast enhancement correlated positively with RV end-diastolic volume/body surface area, RV mass, mean PAP, and pulmonary vascular resistance and correlated inversely with RV ejection fraction. CONCLUSION: DCE was present within the RVIPs and IVS of most patients with PHT studied. Extent of DCE correlated with RV function and pulmonary haemodynamics. DCE was associated with IVS bowing and may provide a novel marker for occult septal abnormalities directly relating to the haemodynamic stress experienced by these patients.

Atrial and ventricular volume and function in persistent and permanent atrial fibrillation, a magnetic resonance imaging study.

Left atrial size is independently related to cardiovascular morbidity and mortality, and atrial fibrillation (AF) is strongly associated with atrial size. Our aims were to report atrial and ventricular dimensions in patients with AF evaluated with magnetic resonance imaging (MRI), and to assess the inter-study reproducibility of the measurements. Nineteen healthy volunteers, 19 patients with permanent AF, and 58 patients with persistent AF had cardiac dimensions evaluated by 6-mm cinematographic breath-hold MRI scans using a 1.5 Tesla Siemens Vision Magnetom scanner with a phased array chest coil. Intraobserver variability and inter-study reproducibility of the cardiac volumes and ejection fractions (EF) gave acceptable Bland-Altman plots, good correlations (R2: 0.80-0.99), and low reproducibility coefficients. The mean atrial volumes were similar in the two groups with AF [systolic vol. index (SVI): 75.9-80.3 mL/m2; diastolic vol. index (DVI): 77.4-82.1 mL/m2] and significantly different from the healthy volunteers (SVI: 30.3 mL/m2; DVI: 62.3 mL/m2; p < 0.0001). Mean left ventricular (LV) volumes and EF were significantly different in permanent AF (SVI: 34.2 mL/m2; DVI: 68.3 mL/m2; EF: 50.8%) compared to persistent AF [SVI: 44.0 mL/m2 (p = 0.02); DVI: 77.2 mL/m2 (p = 0.03); EF: 44.9% (p = 0.02)], and closer to the normal values (SVI: 22.4 mL/m2; DVI: 66.5 mL/m2; EF: 67.0%). MRI is a highly reproducible method for measurement of atrial and ventricular dimensions in healthy volunteers and in patients with AF. Our results suggest that atrial dilatation appears within the first months of AF and stays more or less unchanged thereafter. The LV appears to dilate early as a response to AF, but later seems to adapt.

Matrix metalloproteinase-1 promoter polymorphisms and changes in left ventricular volume following acute myocardial infarction.

The relation between matrix metalloproteinase-1 promoter genotype and remodeling was studied in 42 patients after their first acute myocardial infarctions. Patients possessing 2 GG alleles were at increased risk for remodeling compared with homozygotes for the G allele and heterozygotes possessing 1 G and 1 GG allele.

N-terminal pro brain natriuretic peptide in arterial hypertension--a marker for left ventricular dimensions and prognosis.

In arterial hypertension risk factor evaluation, including LV mass measurements, and risk stratification using risk charts or programs, is generally recommended. In heart failure NT-proBNP has been shown to be a marker of LV dimensions and of prognosis. If the same diagnostic and prognostic value is present in arterial hypertension, risk factor evaluation would be easier. In 36 patients with arterial hypertension, electrocardiographic LV hypertrophy and preserved left ventricular function, NT-proBNP was eight-fold higher than in healthy subjects. The log NT-proBNP correlated with LV mass index (R=0.47, P=0.0002) measured by magnetic resonance imaging. In other subjects with arterial hypertension a significant but weak correlation to diastolic properties has been demonstrated. As for prognosis, a recent study in patients with hypertension, electrocardiographic left ventricular hypertrophy and preserved LV function demonstrated that NT-proBNP was a very strong prognostic marker, especially combined with a history of cardiovascular disease. Patients with high NT-proBNP and known cardiovascular disease had a seven-fold increase in CV events compared to patients with low NT-proBNP and no CV disease, while patients with either high NT-proBNP or CV disease had a three-four-fold increased risk. In conclusion NT-proBNP predicts LV mass in hypertensive patients and is a very strong prognostic marker in these patients. This could indicate a use of NT-proBNP in the future for risk stratification and perhaps monitoring of treatment in patients with arterial hypertension.

Measurement of pulse wave velocity using magnetic resonance imaging.

Arterial stiffness has a strong relationship with cardiovascular disease. Pulse wave velocity (PWV) is increasingly used as a measure of arterial stiffness. The calculation of PWV requires accurate measurement of blood flow velocity and aortic length. Using magnetic resonance imaging (MRI), we are able to accurately acquire blood flow velocity and to virtually measure the aortic length inside the central aorta. Manual measurement of aorta length is inaccurate and subjective. In this study, we set out to develop a method which automatically locates the thoracic aorta and measures aortic length, allowing noninvasive measurement of PWV derived from the aortic flow. Our method is novel, efficient and robust. This offers a reliable and convenient tool for PWV measurement allowing detailed non invasive assessment of cardiovascular risk.

Neurohumoral prediction of left-ventricular morphologic response to beta-blockade with metoprolol in chronic left-ventricular systolic heart failure.

BACKGROUND: In order to tailor therapy in heart failure, a solution might be to develop sensitive and reliable markers that can predict response in individual patients or monitor effectiveness of therapy. AIMS: To evaluate neurohumoral factors as markers for left-ventricular (LV) antiremodelling from metoprolol treatment in patients with chronic LV systolic heart failure. METHODS: Forty-one subjects randomised to placebo or metoprolol were studied with magnetic resonance imaging and blood samples to measure LV dimensions and ejection fraction, epinephrine, norepinephrine, plasma renin activity, aldosterone, atrial (ANP) and brain natriuretic peptides, arginine-vasopressin and endothelin-1 at baseline, 5 weeks and 6 months after randomisation. RESULTS: Baseline ANP was identified as sole independent marker for changes in LV end-diastolic (deltaLVEDVI: r=-0.70, P=0.002), and end-systolic (deltaLVESVI: r=-0.53, P=0.03) volumes during metoprolol treatment. Change in ANP during the study was an independent marker for deltaLVEDVI: r=0.66, P=0.004, and deltaLVESVI: r=0.69, P=0.002 in the entire metoprolol group, but at the individual patient level, results were less clear. CONCLUSION: The pre-treatment plasma level of ANP may be a predictor of LV antiremodelling from treatment with metoprolol in patients with chronic heart failure. However, the potential for individual neurohumoral monitoring of the effects on LV dimensions during beta-blockade appears limited.

Detection of left ventricular enlargement and impaired systolic function with plasma N-terminal pro brain natriuretic peptide concentrations.

BACKGROUND: Brain- and N-terminal pro brain natriuretic peptide (NT-proBNP) have been identified as promising markers for heart failure. However, previous studies have revealed that they may hold insufficient diagnostic power for implementation into clinical practice because of a significant overlap in the range of plasma levels between healthy subjects and subjects with heart failure. We hypothesized that imprecision of the reference method (ie, the echocardiographic evaluation of left ventricular [LV] function) may have affected results from those earlier studies. We therefore wanted to investigate the diagnostic potential of NT-proBNP with magnetic resonance imaging as the reference method for the cardiac measurements. METHODS: Forty-eight patients with stable symptomatic heart failure in New York Heart Association functional classifications II to IV were examined once with blood samples and magnetic resonance imaging along with 20 age-matched and gender-matched healthy control subjects. RESULTS: NT-proBNP was associated with LV end-diastolic (r = 0.69; P <.0001) and end-systolic (r = 0.73; P <.0001) volume indices, LV mass index (r = 0.69; P <.0001), and LV ejection fraction (r = -0.75; P <.0001). Receiver operating characteristic curves were calculated for the ability of NT-proBNP to detect LV end-diastolic volume index (>105 mL. m(-2)[cut-off]; sensitivity/specificity, 82%/87%), LV end-systolic volume index (>35 mL. m(-2); sensitivity/specificity, 86%/86%), LV mass index (>152 g. m(-2); sensitivity/specificity, 85%/86%), and LV ejection fraction (<58%; sensitivity/specificity, 84%/85%) deviating more than 2 standard deviations from control values. CONCLUSION: NT-proBNP is a powerful marker for LV dimensions and systolic function in patients with heart failure and discriminates well between healthy subjects and subjects with impaired LV systolic function or increased LV dimensions.

Left ventricular remodeling in the first year after acute myocardial infarction and the predictive value of N-terminal pro brain natriuretic peptide.

BACKGROUND: Left ventricular (LV) remodeling after myocardial infarction (MI) has received much attention because of its severe impact on morbidity and mortality rates. However, the incidence and extent of LV remodeling in a modern infarct population who were offered antiremodeling treatment in compliance with daily clinical practice is unknown. The purpose of this study was to clarify this issue and to evaluate the predictive value of N-terminal pro brain natriuretic peptide (NT-proBNP). METHODS: Forty-two patients with a first transmural MI were examined after 1 week, 1 month, 3 months, 6 months, and 1 year with blood samples and magnetic resonance imaging. RESULTS: In 12 patients (29%), LV end-diastolic volume index (LVEDVI) and LV end-systolic volume index (LVESVI) increased by 24% and 22% (P <.0001; P =.01). In 12 patients (29%), LVEDVI and LVESVI decreased by 19% and 23% (P <.0001; P =.0005), whereas the remaining 18 patients (43%) had stable conditions regarding these LV measures. LV ejection fraction at baseline was significantly reduced in all patient categories but was unchanged over time. Elevated NT-proBNP level at baseline was identified as an independent predictor of increase in LVEDVI during follow-up examination (P =.007). A baseline level of NT-proBNP >115 pmol/L identified patients who later had LV dilatation develop with a sensitivity and specificity of 89% and 68% (area under curve = 0.77). CONCLUSION: In this 1-year follow-up study of patients with a first transmural MI, approximately 30% had significant increments develop in LVEDVI and LVESVI, and LV ejection fraction remained unchanged. Patients in whom LV dilatation developed could be identified early after the MI with elevated plasma levels of NT-proBNP.