Mechanisms and management of hypertensive heart disease: from left ventricular hypertrophy to heart failure

Gender differences in mortality after acute myocardial infarction with mild to moderate heart failure

BACKGROUND

Heart failure (HF) is associated with poor outcome after acute myocardial infarction (AMI). Women have higher mortality rate than men after AMI, however, it is unknown whether women with HF after AMI have different prognosis than men.

AIM

To compare the prognosis of men and women with AMI and mild-moderate HF.

METHODS

We analyzed data of 3456 consecutive patients with AMI hospitalized in all cardiac care units in Israel during two nationwide surveys.

RESULTS

Among patients with AMI and HF on admission: women were older, had more risk factors, and were less likely to undergo percutaneous coronary angiography/intervention. Women with HF had higher (7-days, 30-days, and 1-year) crude mortality rates than men. However, adjusted mortality rates were not significantly different between genders.

CONCLUSIONS

Women with AMI complicated by HF had higher crude mortality rate than men that was eliminated after multivariate analysis, suggesting that the higher mortality rate may be attributed to increased prevalence of risk factors and lower rate of revascularization and medical therapies among women. Women with AMI and HF should be considered as a high-risk subgroup with adverse outcome. It remains to be determined whether more intensive management will improve their prognosis.

Potential impact of carbohydrate and fat intake on pathological left ventricular hypertrophy

Currently, a high carbohydrate/low fat diet is recommended for patients with hypertension; however, the potentially important role that the composition of dietary fat and carbohydrate plays in hypertension and the development of pathological left ventricular hypertrophy (LVH) has not been well characterized. Recent studies demonstrate that LVH can also be triggered by activation of insulin signaling pathways, altered adipokine levels, or the activity of peroxisome proliferator-activated receptors (PPARs), suggesting that metabolic alterations play a role in the pathophysiology of LVH. Hypertensive patients with high plasma insulin or metabolic syndrome have a greater occurrence of LVH, which could be due to insulin activation of the serine-threonine kinase Akt and its downstream targets in the heart, resulting in cellular hypertrophy. PPARs also activate cardiac gene expression and growth and are stimulated by fatty acids and consumption of a high fat diet. Dietary intake of fats and carbohydrate and the resultant effects of plasma insulin, adipokine, and lipid concentrations may affect cardiomyocyte size and function, particularly in the setting of chronic hypertension. This review discusses potential mechanisms by which dietary carbohydrates and fats ca affect cardiac growth, metabolism, and function, mainly in the context of pressure overload-induced LVH.

AMP-activated protein kinase: Role in metabolism and therapeutic implications

AMP-activated protein kinase (AMPK) is an enzyme that works as a fuel gauge which becomes activated in situations of energy consumption. AMPK functions to restore cellular ATP levels by modifying diverse metabolic and cellular pathways. In the skeletal muscle, AMPK is activated during exercise and is involved in contraction-stimulated glucose transport and fatty acid oxidation. In the heart, AMPK activity increases during ischaemia and functions to sustain ATP, cardiac function and myocardial viability. In the liver, AMPK inhibits the production of glucose, cholesterol and triglycerides and stimulates fatty acid oxidation. Recent studies have shown that AMPK is involved in the mechanism of action of metformin and thiazolidinediones, and the adipocytokines leptin and adiponectin. These data, along with evidence that pharmacological activation of AMPK in vivo improves blood glucose homeostasis, cholesterol concentrations and blood pressure in insulin-resistant rodents, make this enzyme an attractive pharmacological target for the treatment of type 2 diabetes, ischaemic heart disease and other metabolic diseases.

Fatal colonic ischemia: A population-based study

OBJECTIVES

To estimate the incidence of fatal colonic ischaemia (CI) and the cause-specific mortality of CI, and to describe the localization and extension of colonic infarction and quantify the risk factors associated with CI.

MATERIAL AND METHODS

Between 1970 and 1982 the autopsy rate in Malmö, Sweden, was 87%, creating the possibilities for a population-based study. Out of 23,446 clinical autopsies, 997 cases were coded for intestinal ischaemia in a database. In addition, 7569 forensic autopsy protocols were analysed. In a case-control study nested in the clinical autopsy cohort, four CI-free controls, matched for gender, age at death and year of death, were identified for each fatal CI case in order to evaluate the risk factors.

RESULTS

The cause-specific mortality ratio was 1.7/1000 autopsies. The overall incidence of autopsy-verified fatal CI was 1.7/100,000 person years, increasing with age up to 23/100,000 person years in octogenarians. Fatal cardiac failure (odds ratio (OR) 5.2), fatal valvular disease (OR 4.3), previous stroke (OR 2.5) and recent surgery (OR 3.4) were risk factors for fatal CI. Narrowing/occlusion of the inferior mesenteric artery (IMA) at the aortic origin was present in 68% of the patients. The most common segments affected by transmural infarctions were the sigmoid (83%) and the descending (77%) colon.

CONCLUSIONS

Heart failure, atherosclerotic occlusion/stenoses of the IMA and recent surgery were the main risk factors causing colonic hypoperfusion and infarction. Segments of transmural infarctions were observed within the left colon in 94% of the patients. Awareness of the diagnosis and its associated cardiac comorbidities might help to improve survival.

Fatal nonocclusive mesenteric ischaemia: population-based incidence and risk factors

OBJECTIVES

To estimate the incidence and extension of visceral organ infarction, and to evaluate potential causes, in patients with autopsy-verified nonocclusive mesenteric ischaemia (NOMI) and transmural intestinal infarction.

SETTING

In Malmö, Sweden, the autopsy rate between 1970 and 1982 was 87%, creating possibilities for a population-based study.

DESIGN

Amongst 23 446 clinical autopsies, 997 cases were coded for intestinal ischaemia in a database. In addition, 7569 forensic autopsy protocols were analysed. In a nested case-control study within the clinical autopsy cohort, four NOMI-free controls, matched for gender, age at death and year of death, were identified for each fatal NOMI case to evaluate risk factors.

RESULTS

The overall incidence of autopsy-verified fatal NOMI was 2.0/100,000 person-years, increasing with age up to 40/100,000 person-years in octogenarians. Patients with stenosis of the superior mesenteric artery (SMA; n = 25) were older (P = 0.002) than those without (n = 37), and had more often a concomitant stenosis of the coeliac trunk (P < 0.001). Synchronous infarction in the liver, spleen or kidney occurred in one-fifth of all patients. Fatal cardiac failure [OR 2.9 (1.7-5.2)], history of atrial fibrillation [OR 2.2 (1.2-4.0)] and recent surgery [OR 3.4 (1.6-6.9)] were risk factors for fatal NOMI.

CONCLUSIONS

Fatal heart failure was the leading cause of intestinal hypoperfusion, although stenosis of the SMA and coeliac trunk, atrial fibrillation and recent surgery contributed significantly. Collaboration across specialties seems to be of utmost importance to improve the prognosis.

Functional interaction of a beta-adrenergic agonist and cyclic GMP phosphodiesterase inhibitor in control and hypertrophic cardiomyocytes

This study tested the hypothesis that the positive inotropic effect of beta-adrenoceptor stimulation would be inhibited by increases in cyclic GMP in control cardiomyocytes and that this response would be modified in hypertrophic cardiomyocytes. Cell functional data as well as GMP and cyclic AMP data were collected from 7 control and 7 1K1C (one-kidney-one-clip) renal hypertensive hypertrophic rabbits. Using isolated control and IKIC ventricular myocytes, data were obtained at baseline and after treatment with the beta-adrenoceptor agonist isoproterenol (10(-8, -6) mol/l) or the cyclic GMP-phosphodiesterase inhibitor zaprinast (10(-5) mol/l) followed by isoproterenol (10(-8, -6) mol/l). We found that in control rabbits, isoproterenol (10(-6) mol/l) increased percent shortening (4.8 +/- 0.2 to 6.4 +/- 0.3%) and cyclic AMP (2.3 +/- 0.3 to 5.0 +/- 0.7 pmol/10(5) cells). Zaprinast 10(-5) mol/l increased cyclic GMP (150 +/- 20 to 209 +/- 14 fmol/10(5) cells) and decreased percent shortening (6.2 +/- 0.4 to 5.2 +/- 0.3). Zaprinast 10(-5) mol/l prevented the functional response to isoproterenol in control (5.2 +/- 0.3 to 4.7 +/- 0.3), without changing cyclic AMP levels. In 1K1C rabbits, isoproterenol (10(-6) mol/l) increased cyclic AMP (4.9 +/- 0.8 to 7.6 +/- 1.4 pmol/10(5) cells) without changing function. Zaprinast 10(-5) mol/l increased cyclic GMP (182 +/- 23 to 233 +/- 24 fmol/10(5) cells) and decreased percent shortening (6.6 +/- 0.9 to 4.7 +/- 0.5), but did not alter the lack of effect of isoproterenol in 1K1C. In control cardiomyocytes, cyclic GMP blunted the isoproterenol contraction response without changing cyclic AMP levels, but isoproterenol's functional effect was not seen in 1K1C cardiomyocytes.

The evaluation of left ventricular hypertrophy in hypertensive patients with subclinical hyperthyroidism

The aim of this prospective cross-sectional study was to investigate the hypertrophic effects of endogenous subclinical hyperthyroidism on myocardium and early development of left ventricular hypertrophy (LVH) in essential hypertensive patients accompanied by endogenous subclinical hyperthyroidism. A total of 31 consecutive patients with stage I hypertension were included in the study. Sixteen of them also had endogenous subclinical hyperthyroidism that they were unaware before. The patients and the controls formed out of ten healthy subjects all underwent an investigation of thyroid functions and cardiologic evaluation. The mean wall thickness of the left ventricle in the stage I hypertensive group with endogenous subclinical hyperthyroidism (group I) was significantly increased as compared with both hypertensive patients without thyroid disease (group II) and the control subjects. The mean left ventricle mass was also significantly higher in group I than group II. Both of the patients' groups had an increased prevalence of LVH as compared with the controls. In this study, hypertensive patients with subclinical hyperthyroidism presented more increase in left ventricular mass, suggesting that subclinical hyperthyroidism may contribute to left ventricular hypertrophy forming a natural progression to hypertension. The hypertensive population should always be screened for endogenous subclinical hyperthyroidism, and should be examined for the criteria of left ventricular hypertrophy by echocardiography in early stages.

Hypertrophy in the female heart

Several clinical studies have suggested that sex influences the left ventricle's response to altered loading conditions and thus the development of cardiac hypertrophy. Likewise, several of the risk factors associated with the development of hypertrophy exhibit sexual dimorphism in their distribution in the general population. These sex-specific differences in risk factor distribution are likely important modifiers in disease progression and outcome. This review explores the available evidence of sex-specific differences in the evolution of left ventricular hypertrophy.

Losartan

Losartan (Cozaar) is an angiotensin AT1 receptor antagonist. It is approved in numerous countries for the treatment of hypertension and has been approved in the UK, the US and several European countries for stroke risk reduction in patients with hypertension and left ventricular hypertrophy (LVH). Losartan is recommended for use alone or with hydrochlorothiazide, but it can also be administered with other antihypertensive medications. In patients with hypertension, losartan effectively lowers blood pressure and also leads to regression of LVH. In the large, well designed LIFE (Losartan Intervention For Endpoint reduction in hypertension) study in patients with hypertension and LVH, losartan was more effective than atenolol in reducing the composite primary endpoint of cardiovascular (CV) mortality, stroke or myocardial infarction (MI). This was mainly due to a significant 25% reduction in the risk of stroke in the losartan group. Losartan recipients also had a significantly lower incidence of new-onset diabetes mellitus compared with atenolol recipients. Similar benefits were observed in several patient subgroups from the LIFE study, but not in the subgroup of Black patients. Losartan is well tolerated and is a cost effective alternative to atenolol in the setting of stroke reduction. Comparative data on clinical outcomes in hypertensive patients for losartan versus other antihypertensive agents would be of interest. Nonetheless, in addition to its established antihypertensive and end organ effects, the LIFE study indicates that, with the possible exception of Black patients, losartan can reduce the risk of stroke in patients with hypertension and LVH.