Left Atrial Remodeling Following ST-Segment-Elevation Myocardial Infarction Correlates With Infarct Size and Age Older Than 70 Years

Background Following myocardial infarction, left ventricular remodeling (LVR) is associated with heart failure and cardiac death. At the same time, left atrial (LA) remodeling (LAR) is an essential part of the outcome of a wide spectrum of cardiac conditions. The authors sought to evaluate the correlates of LAR and its relationships with LVR after myocardial infarction. Methods and Results This is a retrospective analysis of 320 of 443 patients enrolled for study of LVR after ST-elevation myocardial infarction. Left ventricular (LV) volumes, infarct size and LA volume index were assessed by cardiac magnetic resonance imaging during index hospitalization (day 6 [interquartile range, 4-8]) and after a 3-month follow-up. LAR was studied using a linear mixed model for repeated measurements. Overall, there was a decrease in LA volume index between 6 days and 3 months (43.9±10.4 mL versus 42.8±11.1 mL, P=0.003). Patients with changes in LA volume index >8% over time were older, with greater body mass index, lower LV ejection fraction, and larger infarct size. Unadjusted predictors of LAR were age older than 70 years, infarct size, anterior infarction, time to reperfusion, history of hypertension, LV end-diastolic volume, and heart failure at day 6. Independent correlates were age older than 70 years (3.24±1.33, P=0.015) and infarct size (2.16±0.72 per 10% LV, P<0.001). LA remodeling was correlated with LV remodeling (r=0.372, P<0.001), but neither LA nor LV volumes at day 6 were related to LVR or LAR, respectively. Conclusions The authors found LA changes to occur in the months after myocardial infarction, with an overall decrease in LA volumes. While LAR coincided with LVR, the correlates for LAR were age older than 70 years and larger infarct size.

Biomechanics of Cardiac Function

The heart pumps blood to maintain circulation and ensure the delivery of oxygenated blood to all the organs of the body. Mechanics play a critical role in governing and regulating heart function under both normal and pathological conditions. Biological processes and mechanical stress are coupled together in regulating myocyte function and extracellular matrix structure thus controlling heart function. Here, we offer a brief introduction to the biomechanics of left ventricular function and then summarize recent progress in the study of the effects of mechanical stress on ventricular wall remodeling and cardiac function as well as the effects of wall mechanical properties on cardiac function in normal and dysfunctional hearts. Various mechanical models to determine wall stress and cardiac function in normal and diseased hearts with both systolic and diastolic dysfunction are discussed. The results of these studies have enhanced our understanding of the biomechanical mechanism in the development and remodeling of normal and dysfunctional hearts. Biomechanics provide a tool to understand the mechanism of left ventricular remodeling in diastolic and systolic dysfunction and guidance in designing and developing new treatments.

Development and course of heart failure after a myocardial infarction in younger and older people

Background

Acute myocardial infarction (AMI) is a common cause of heart failure (HF), which can develop soon after AMI and may persist or resolve or develop late. HF after an MI is a major source of mortality. The cumulative incidence, prevalence and resolution of HF after MI in different age groups are poorly described. This study describes the natural history of HF after AMI according to age.

Methods

Patients with AMI during 1998 were identified from hospital records. HF was defined as treatment of symptoms and signs of HF with loop diuretics and was considered to have resolved if loop diuretic therapy could be stopped without recurrence of symptoms. Patients were categorised into those aged < 65 years, 65–75 years, and > 75 years.

Results

Of 896 patients, 311, 297 and 288 were aged < 65, 65–75 and >75 years and of whom 24%, 57% and 82% had died respectively by December 2005. Of these deaths, 24 (8%), 68 (23%) and 107 (37%) occurred during the index admission, many associated with acute HF. A further 37 (12%), 63 (21%) and 82 (29%) developed HF that persisted until discharge, of whom 15, 44 and 62 subsequently died. After discharge, 53 (24%), 55 (40%) and 37 (47%) patients developed HF for the first time, of whom 26%, 62% and 76% subsequently died. Death was preceded by the development of HF in 35 (70%), 93 (91%) and 107 (85%) in aged < 65 years, 65–75 years and >75 years, respectively.

Conclusions

The risk of developing HF and of dying after an MI increases progressively with age. Regardless of age, most deaths after a MI are preceded by the development of HF.

Circulating levels of hepatocyte growth factor and left ventricular remodelling after acute myocardial infarction (from the REVE-2 study)

Aim As experimental studies suggest that hepatocyte growth factor (HGF) is cardioprotective after myocardial infarction (MI), this study sought to investigate relationships between circulating levels of HGF and left ventricular (LV) remodelling in patients after acute MI.

METHODS AND RESULTS

This prospective multicentre study included 246 patients with a first anterior Q-wave MI. Serial echocardiographic studies were performed at hospital discharge and 3 and 12 months after MI; quantitative analysis was performed at a core echocardiography laboratory. Blood samples to measure HGF, brain natriuretic peptide (BNP), and C-reactive protein were obtained at discharge and at the 1, 3, and 12 month follow-up visits. Plasma HGF levels were high at baseline, decreased at 1 month, and remained stable thereafter. In the post-MI period (at 3 and 12 months), HGF levels were positively associated with LV volumes, wall motion systolic index, E/Ea, and BNP; and negatively with LV ejection fraction. High HGF levels were associated with higher C-reactive protein levels. Multivariate analysis showed that both BNP (P < 0.0001) and C-reactive protein (P < 0.0001) were independently associated with HGF levels at 3 and 12 months. Patients who died or were rehospitalized for heart failure during follow-up had higher HGF levels at 1 month (P = 0.0006), 3 months (P = 0.018), and 1 year (P = 0.006) after MI.

CONCLUSIONS

Circulating HGF levels correlate with all markers of LV remodelling after MI and are associated with rehospitalization for heart failure.

Threshold haemoglobin levels and the prognosis of stable coronary disease: two new cohorts and a systematic review and meta-analysis

BACKGROUND

Low haemoglobin concentration has been associated with adverse prognosis in patients with angina and myocardial infarction (MI), but the strength and shape of the association and the presence of any threshold has not been precisely evaluated.

METHODS AND FINDINGS

A retrospective cohort study was carried out using the UK General Practice Research Database. 20,131 people with a new diagnosis of stable angina and no previous acute coronary syndrome, and 14,171 people with first MI who survived for at least 7 days were followed up for a mean of 3.2 years. Using semi-parametric Cox regression and multiple adjustment, there was evidence of threshold haemoglobin values below which mortality increased in a graded continuous fashion. For men with MI, the threshold value was 13.5 g/dl (95% confidence interval [CI] 13.2-13.9); the 29.5% of patients with haemoglobin below this threshold had an associated hazard ratio for mortality of 2.00 (95% CI 1.76-2.29) compared to those with haemoglobin values in the lowest risk range. Women tended to have lower threshold haemoglobin values (e.g, for MI 12.8 g/dl; 95% CI 12.1-13.5) but the shape and strength of association did not differ between the genders, nor between patients with angina and MI. We did a systematic review and meta-analysis that identified ten previously published studies, reporting a total of only 1,127 endpoints, but none evaluated thresholds of risk.

CONCLUSIONS

There is an association between low haemoglobin concentration and increased mortality. A large proportion of patients with coronary disease have haemoglobin concentrations below the thresholds of risk defined here. Intervention trials would clarify whether increasing the haemoglobin concentration reduces mortality.

Key role of Doppler echocardiography in the emergency management of elderly patients

Owing to modern epidemiology in Western countries, ageing represents a growing health burden. In general, because of age itself and comorbid conditions, all clinical cardiovascular manifestations have a higher mortality rate and a worse outcome in older people compared with in younger individuals. Diagnosis of the disease in the elderly in an emergency setting is particularly challenging for the practitioner. Age-related cardiovascular changes and comorbid conditions may alter signs, symptoms and adaptation to the disease and response to treatment. Bedside Doppler echocardiography is likely to play a major role in guiding diagnosis, therapeutic strategies and prognosis. The purpose of this review is to appraise the application of echocardiographic examination in helping the clinician facing emergency situations that involve the cardiovascular system in the older population.