Left Atrial Mechanics and Diastolic Function Among People Living With Human Immunodeficiency Virus (from the Veterans Aging Cohort Study)

Human immunodeficiency virus (HIV) infection is associated with subclinical cardiomyopathy, diastolic dysfunction, and increased risk of cardiovascular death. However, the relationship between left atrial (LA) mechanics and left ventricular (LV) diastolic function has not been evaluated in people living with HIV (PLWH) relative to HIV-uninfected (HIV-) controls. This is a multicenter, cross-sectional cohort analysis using the HIV Cardiovascular Disease substudy of the Veterans Aging Cohort Study database, which aimed to examine a cohort of PLWH and HIV- veterans without known cardiovascular disease. A total of 277 subjects (180 PLWH, 97 HIV-) with echocardiograms were identified. LV and LA phasic strain were derived and diastolic function was evaluated. Relationship between LA strain, LV strain, and the degree of diastolic dysfunction were assessed using analysis of variance and ordinal logistic regression with propensity weighting. In the PLWH cohort, 91.7% were on antiretroviral therapy and 86.1% had HIV viral loads <500 copies/ml. The mean (± SD) duration of infection was 9.7 ± 4.9 years. Relative to HIV- veterans, PLWH did not differ in LA mechanics and proportion of diastolic dysfunction (p = 0.31). Using logistic regression with propensity weighting, we found no association between HIV status and degree of diastolic dysfunction. In both cohorts, LA reservoir strain and LA conduit strain were inversely and independently associated with the degree of diastolic dysfunction. Compared with HIV- veterans, PLWH who are primarily virally suppressed and antiretroviral-treated did not differ in LA strain or LV diastolic dysfunction. If confirmed in other cohorts, HIV viral suppression may curtail adverse alterations in cardiac structure and function.

Inpatient Quality-of-Care Measures for Heart Failure: Treatment Gaps and Opportunities in the Contemporary Era

BACKGROUND:

Quality of care measures are vital tools to assess processes of care within and between health care systems. The 2020 American College of Cardiology/AHA performance measures for heart failure provide a new set of such measures. We evaluated the achievement of these and other performance measures within the Veterans Affairs hospital system in a contemporary cohort of patients hospitalized for heart failure.

METHODS:

Hospital discharges from January 2010 to February 2021 with a primary diagnosis of heart failure (n=289 810) were evaluated. Adherence to each measure was determined using the measure’s stated definition and by site.

RESULTS:

Among patients with reduced ejection fraction (53.0%), beta blocker use was high (89.0%), ACE (angiotensin-converting enzyme) inhibitor, angiotensin receptor blocker, or angiotensin receptor-neprilysin inhibitor (ARNI) use decreased over time (75.3% in 2010, 55.8% in 2020), and hydralazine/nitrate use in eligible Black patients (19.3%) was low. While 68.1% were eligible for ARNI, only 6.0% received them, reaching 17.2% by 2020. Mineralocorticoid receptor antagonists were used in 49.3% of those eligible; laboratory testing 7 days after their initiation was 73.0%, detecting hyperkalemia in 2.2%, although it occurred in 13.7% by 90 days. Achievement of ≥50% target dose was low (beta blocker 45.9%, ACE inhibitor/angiotensin receptor blocker 31.6%, ARNI 19.0%) and for ACE inhibitor/angiotensin receptor blocker/ARNI, decreased over time. Discharge appointments were 56.2% at 7 days and 78.8% at 14 days. Cardiac rehabilitation referral was low (10.5%) but increased. There were significant site-level differences, particularly for hydralazine, ARNI, devices, and cardiac rehabilitation.

CONCLUSIONS:

Important inpatient quality of care measures can be readily measured across the Veterans Administration health care system from electronic health records. Treatment gaps and site-level differences persisted into the contemporary era and will likely be exacerbated as newer treatments are added to this complex baseline. These measures and methods also offer the opportunity to target global, local, and individual processes of care for innovative quality improvement initiatives.

Advances in the treatment of transthyretin cardiac amyloidosis: Current and emerging therapies

Transthyretin cardiac amyloidosis (ATTR-CA) has been recognized as an underdiagnosed and undertreated cause of heart failure with often unrecognized multiorgan involvement. Guideline development and the establishment of nonbiopsy criteria for diagnosis of ATTR-CA have led to an increased rate of diagnosis and hence patients referred for therapies. ATTR is a protein misfolding disorder where the TTR tetramer disassociates into monomers which form insoluble amyloid depositions in organs, including the heart. ATTR-CA can be due to autosomal dominant transmitted gene mutation or due to misfolding of wild-type TTR. Prior to 2019, there were no FDA-approved pharmacological treatments for ATTR-CA. Understanding of ATTR-CA pathogenesis has enabled development of targeted strategies with novel disease-modifying therapies. Current and emerging therapies for ATTR-CA include (1) TTR gene silencing (siRNA, ASO, CRISPR/Cas9), (2) TTR tetramer stabilization, and (3) TTR amyloid fibril degradation. This review focuses on the pathophysiology of ATTR-CA, diagnostic criteria, and addresses current and emerging treatments for this diverse disorder.

Bleeding Risk of Direct Oral Anticoagulants in Patients With Heart Failure And Atrial Fibrillation

BACKGROUND

Patients with heart failure and atrial fibrillation are an important atrial fibrillation subgroup in which direct oral anticoagulants (DOACs) have not been adequately studied in real-world settings. Since DOACs rely on renal elimination and renal dysfunction is prevalent in patients with heart failure, their use may increase bleeding risk, negating some of their advantage over warfarin.

METHODS

We conducted a retrospective cohort study using linked Veterans Administration databases of patients with heart failure newly started on warfarin or DOACs for atrial fibrillation from October 2010 to August 2017 (23 635 warfarin, 25 823 DOAC). Outcomes included time to first bleeding, stroke, and death using Cox proportional hazards models with inverse probability of treatment weighting.

RESULTS

Total bleeding (hazard ratio, 0.62 [95% CI, 0.56-0.68]), major bleeding (hazard ratio, 0.49 [95% CI, 0.40-0.61]), and death (hazard ratio, 0.74 [95% CI, 0.71-0.78]) were lower with DOAC than warfarin, and with apixaban and dabigatran, but not rivaroxaban. Moderate/severe chronic kidney disease was common (48.7%); moderate chronic kidney disease was associated with increased bleeding with DOACs but not warfarin. However, death and bleeding remained lower with DOACs than warfarin across all renal function levels and clinical subgroups. A >20% transient/persistent decline in renal function occurred in 53% of DOAC-treated patients at some point during follow-up, would have required dose reduction in 10.5% of patients, and was associated with increased bleeding. Dose adjustments were made more often, and bleeding and death were lower in patients seen by pharmacists or anticoagulation clinics. There were significant between-site variations in DOAC dosing.

CONCLUSIONS

DOACs overall, apixaban, and dabigatran, but not rivaroxaban, were associated with less total bleeding and death than warfarin in patients with heart failure and atrial fibrillation at all levels of renal function. Renal function decline resulted in increased bleeding in patients with DOACs. DOAC dose adjustment was often indicated, associated with increased bleeding when not adjusted, emphasizing the need for closer monitoring in these patients.

DISCOVERY: prevalence of transthyretin (TTR) mutations in a US-centric patient population suspected of having cardiac amyloidosis

BACKGROUND

Hereditary transthyretin-mediated amyloidosis (hATTR amyloidosis) is a multisystem disease that presents with polyneuropathy and/or cardiomyopathy.

METHODS

DISCOVERY, a multicenter screening study, enrolled patients with clinically suspected cardiac amyloidosis to determine the frequency of transthyretin (TTR) mutations and assess disease characteristics.

RESULTS

Of 1007 patients, the majority were from the US (84%), Black/African American (56%), male (63%), and with a mean (standard deviation) age of 65 (13) years. Among 1001 patients with genotyping results, 74 (7%) had a pathogenic TTR mutation (71/836 [8%] from the US). Val122Ile was the most common mutation, found in 11% of Black/African American patients overall; Black/African American ethnicity was an independent predictor of having a pathogenic TTR mutation. Additional independent predictors of such mutations in the total population and Black/African American group were interventricular septum thickness, low electrocardiogram voltage, and age.

CONCLUSIONS

Pathogenic TTR mutations occurred in 8% of US patients with suspected cardiac amyloidosis. Most mutations were Val122Ile, almost exclusively found in Black/African American patients. Disease often remains undetected until advanced and difficult to treat, therefore, clinicians should assess at-risk patients for hATTR amyloidosis as early as possible.

Association of Syndemic Unhealthy Alcohol Use, Cigarette Use, and Depression With All-Cause Mortality Among Adults Living With and Without HIV Infection: Veterans Aging Cohort Study

Background

The prevalence and risk of concurrent unhealthy drinking, cigarette use, and depression on mortality among persons living with HIV (PLWH) is unclear. This study applied a syndemic framework to assess whether these co-occurring conditions increase mortality and whether such risk is differential by HIV status.

Methods

We evaluated 6721 participants (49.8% PLWH) without baseline cancer from the Veterans Aging Cohort Study, a prospective, observational cohort of PLWH and matched uninfected veterans enrolled in 2002 and followed through 2015. Multivariable Cox proportional hazards regressions estimated risk of a syndemic score (number of conditions: that is, unhealthy drinking, cigarette use, and depressive symptoms) on all-cause mortality by HIV status, adjusting for demographic, health status, and HIV-related factors.

Results

Fewer than 10% of participants had no conditions; 25.6% had 1, 51.0% had 2, and 15.0% had all 3. There were 1747 deaths (61.9% PLWH) during the median follow-up (11.4 years). Overall, age-adjusted mortality rates/1000 person-years increased with a greater number of conditions: (0: 12.0; 1: 21.2; 2: 30.4; 3: 36.3). For 3 conditions, the adjusted hazard ratio of mortality was 36% higher among PLWH compared with uninfected participants with 3 conditions (95% confidence interval, 1.07–1.72; P = .013), after adjusting for health status and HIV disease progression. Among PLWH and uninfected participants, mortality risk persisted after adjustment for time-updated health status.

Conclusions

Syndemic unhealthy drinking, cigarette use, and depression are common and are associated with higher mortality risk among PLWH, underscoring the need to screen for and treat these conditions.

Impact of a Multidisciplinary Heart Failure Post-hospitalization Program on Heart Failure Readmission Rates

BACKGROUND

Specialized chronic heart failure (HF) clinics have demonstrated significant reductions in readmissions. Limited evidence is available regarding HF clinics in the immediate post-discharge period.

OBJECTIVE

To evaluate the effect of a multidisciplinary HF clinic on 90-day readmission rates and all-cause mortality in those recently discharged from a HF hospitalization.

METHODS

In this retrospective cohort study, patients discharged with a primary HF diagnosis who attended the HF postdischarge clinic in 2010-2012 were compared with controls from 2009. During 6 clinic visits, patients were seen by a physician assistant, clinical pharmacist specialist, and case manager, with care overseen by a cardiologist. The program focused on optimizing therapy, identifying HF etiology/precipitating factors, medication titration, education, and medication adherence. The primary outcome was 90-day HF readmission. A multivariate Cox proportional hazards model was used to compare outcomes.

RESULTS

Among the 277 patients (144 clinic, 133 control) in the study, 7.6% of patients in the clinic and 23.3% of patients in the control group were readmitted for HF within 90 days (aHR (adjusted hazard ratio) = 0.17; 95% CI = 0.07-0.41; P < 0.001; ARR (absolute risk reduction) = 15.7%; NNT (number needed to treat) = 7). Clinic patients had lower 90-day time-to-first HF readmission or all-cause mortality (9.0% vs 28.6%; aHR = 0.28; 95% CI = 0.06-0.31; P < 0.001; ARR = 19.6%; NNT = 6).

CONCLUSIONS

The multidisciplinary HF posthospitalization outpatient program was associated with a significant reduction in 90-day HF readmissions in patients who were recently discharged from a HF hospitalization.

Predictors of erythropoietin use in patients with cardiorenal anaemia syndrome

Objectives

Chronic kidney disease (CKD) and anemia are common in patients with heart failure (HF) – these 3 conditions have been coined the Cardiorenal Anemia Sydrome (CRAS). The National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-K/DOQI) guidelines do not specifically address patients with CRAS, creating uncertainty in erythropoietin (EPO) prescribing. We sought to determine predictors of EPO use in patients with CRAS.

Methods

We conducted a retrospective cohort study at the Veteran’s Affairs Greater Los Angeles Healthcare System (VAGLAHS), a 300+ bed facility that provides primary and tertiary inpatient, and ambulatory care services, between January 1, 2003 to December 31, 2006. A multiple logistic regression model was constructed to identify predictors of EPO use among CRAS patients.

Key findings

Of 2058 patients with CRAS, 213 (10.3%) were prescribed EPO. There were significant differences in baseline characteristics between the EPO and non-EPO groups. The following predictors were found to be associated with EPO prescription: iron supplementation (odds ratio [OR] 52.70, 95% confidence interval [CI] 11.70–237.46), renal clinic appointment (OR 2.60, 95% CI 1.79–3.76), malignancy (OR 1.52, 95% CI 1.07–2.16) and use of hydralazine/nitrates (OR 1.41, 95% CI 1.03–1.92). There was an inverse association found between EPO prescription and baseline hemoglobin (OR 0.61, 95% CI 0.53–0.70) and eGFR (OR 0.96, 95% CI 0.94–0.97).

Conclusion

A small proportion of patients eligible for EPO therapy according to guidelines at the time of the study were prescribed the indicated therapy. Markers of declining renal function or those suggesting need for anemia therapy were identified as EPO predictors.

Prehypertension, hypertension, and the risk of acute myocardial infarction in HIV-infected and -uninfected veterans

BACKGROUND

Compared to uninfected people, human immunodeficiency virus (HIV)-infected individuals may have an increased risk of acute myocardial infarction (AMI). Currently, HIV-infected people are treated to the same blood pressure (BP) goals (<140/90 or <130/80 mm Hg) as their uninfected counterparts. Whether HIV-infected people with elevated BP have excess AMI risk compared to uninfected people is not known. This study examines whether the association between elevated BP and AMI risk differs by HIV status.

METHODS

The Veterans Aging Cohort Study Virtual Cohort (VACS VC) consists of HIV-infected and -uninfected veterans matched 1:2 on age, sex, race/ethnicity, and clinical site. For this analysis, we analyzed 81 026 people with available BP data from VACS VC, who were free of cardiovascular disease at baseline. BP was the average of the 3 routine outpatient clinical measurements performed closest to baseline (first clinical visit after April 2003). BP categories used in the analyses were based on criteria of the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Analyses were performed using Cox proportional hazards regression.

RESULTS

Over 5.9 years (median), 860 incident AMIs occurred. Low/high prehypertensive and untreated/treated hypertensive HIV-infected individuals had increased AMI risk compared to uninfected, untreated normotensive individuals (hazard ratio [HR], 1.60 [95% confidence interval {CI}, 1.07-2.39]; HR, 1.81 [95% CI, 1.22-2.68]; HR, 2.57 [95% CI, 1.76-3.76]; and HR, 2.76 [95% CI, 1.90-4.02], respectively).

CONCLUSIONS

HIV, prehypertensive BP, and hypertensive BP were associated with an increased risk of AMI in a cohort of HIV-infected and -uninfected veterans. Future studies should prospectively investigate whether HIV interacts with BP to further increase AMI risk.

The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study

OBJECTIVES

We sought to evaluate approaches used to control rate, the effectiveness of rate control, and switches from one drug class to another in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study.

BACKGROUND

The AFFIRM study showed that atrial fibrillation (AF) can be treated effectively with rate control and anticoagulation, but drug efficacy to control rate remains uncertain.

METHODS

Patients (n = 2,027) randomized to rate control in the AFFIRM study were given rate-controlling drugs by their treating physicians. Standardized rate-control efficacy criteria developed a priori included resting heart rate and 6-min walk tests and/or ambulatory electrocardiographic results.

RESULTS

Average follow-up was 3.5 +/- 1.3 years. Initial treatment included a beta-adrenergic blocker (beta-blocker) alone in 24%, a calcium channel blocker alone in 17%, digoxin alone in 16%, a beta-blocker and digoxin in 14%, or a calcium channel blocker and digoxin in 14% of patients. Overall rate control was achieved in 70% of patients given beta-blockers as the first drug (with or without digoxin), 54% with calcium channel blockers (with or without digoxin), and 58% with digoxin alone. Adequate overall rate control was achieved in 58% of patients with the first drug or combination. Multivariate analysis revealed an association between first drug class and several clinical variables. There were more changes to beta-blockers than to the other two-drug classes (p < 0.0001).

CONCLUSIONS

Rate control in AF is possible in the majority of patients with AF. Beta-blockers were the most effective drugs. To achieve the goal of adequate rate control in all patients, frequent medication changes and drug combinations were needed.

4-aminopyridine influences heart rate variability in long-standing spinal cord injury

Humans with traumatic spinal myelopathy exhibit intralesional conduction block and autonomic failure as pathophysiologic sequelae of their injury. Analysis of heart rate variability (HRV) provides a means of assessing changes in the function of the autonomic nervous system (ANS) and the cardiac sequelae of injury. Thirteen patients with long-standing spinal cord injury (SCI) and 13 able-bodied controls were studied. Each patient received a single 10-mg dose of an immediate release (IR) formulation of 4-aminopyridine (4-AP). Twenty-four hour heart rate (HR) and HRV data were acquired using a Holter ambulatory electrocardiographic (ECG) monitor. Analysis of acquired data was carried out using a minicomputer programmed to separate ECG R-R intervals into frequency patterns that appear as peaks dispersed along a frequency range of 0.0 to 1.0 Hz. Twenty-four hour baseline, pretreatment low-frequency (LF) HRV power was diminished in all patients with SCI compared with able-bodied-controls and was significantly decreased in tetraplegic patients (P = 0.03). This difference in LF HRV power disappeared during the 24 hours immediately after administration of 4-AP, and mean LF HRV power in tetraplegic patients became indistinguishable from LF HRV power in controls. 4-Aminopyridine appears to influence ANS function and LF HRV in humans with long-standing SCI.

Physical mapping of resistant and susceptible soybean genomes near the soybean cyst nematode resistance gene Rhg4

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, is the foremost pest of soybean (Glycine max L. Merr.). The rhg1 allele on linkage group (LG) G and the Rhg4 allele on LG A2 are important in conditioning resistance. Markers closely linked to the Rhg4 locus were used previously to screen a library of bacterial artificial chromosome (BAC) clones from susceptible 'Williams 82' and identified a single 150-kb BAC, Gm_ISb001_056_G02 (56G2). End-sequenced subclones positioned onto a restriction map provided landmarks for identifying the corresponding region from a BAC library from accession PI 437654 with broad resistance to SCN. Seventy-three PI 437654 BACs were assigned to contigs based upon HindIII restriction fragment profiles. Four contigs represented the PI 437654 counterpart of the 'Williams 82' BAC, with PCR assays connecting these contigs. Some of the markers on the PI 437654 contigs are separated by a greater physical distance than in the 'Williams 82' BAC and some primers amplify bands from BACs in the mid-portion of the connected PI 437654 BAC contigs that are not amplified from the 'Williams 82' BAC. These observations suggest that there is an insertion in the PI 437654 genome relative to the 'Williams 82' genome in the Rhg4 region.

Heart rate variability is altered following spinal cord injury

Spinal cord injury (SCI) patients are known to suffer from autonomic failure as a result of their injury. The magnitude of the dysautonomia resulting from such an injury is difficult to predict or characterize and, in varying degree, it impedes the recovery of physiological homeostasis. This study is intended to investigate the effectiveness of heart rate variability (HRV) analysis as a method of quantifying and characterizing autonomic function in patients with traumatic spinal myelopathy. HRV analysis was carried out in 13 male SCI patients (six tetraplegic, seven paraplegic) and 13 age-matched, able-bodied controls. Twenty-four hour ambulatory and sleep ECG tracings were obtained. Time domain, amplitude, and power spectral analyses were used to study HRV and autonomic function. Both tetraplegic (20+/-12 ms, mean+/-SD) and paraplegic (22+/-8 ms) subjects demonstrated significant loss of low frequency 24-hour HRV compared to able-bodied controls (36+/-14 ms, p < 0.05) and during sleep. This was interpreted as being consistent with predominantly sympathetic denervation uninfluenced by degree of physical activity. There were no significant differences between groups in parasympathetically mediated high frequency HRV. We conclude that HRV analysis is capable of distinguishing between SCI or able-bodied humans and among tetraplegic and paraplegic patients. Patterns of altered HRV may be useful in more completely characterizing or stratifying changes in physiology associated with injury level and may have diagnostic, prognostic, or therapeutic significance.

Effects of beta-adrenergic blockade on papillary muscle function and the beta-adrenergic receptor system in noninfarcted myocardium in compensated ischemic left ventricular dysfunction

BACKGROUND

beta-Adrenergic receptor blockade has been reported to improve hemodynamics and beta-adrenergic receptor-adenylate cyclase function in idiopathic dilated cardiomyopathy. The purpose of this study was to determine the effects of beta-adrenergic receptor blockade on the beta-adrenergic receptor system and myocardial function in a model of compensated ischemic heart failure.

METHODS AND RESULTS

We examined the effects of propranolol treatment on the beta-adrenergic receptor-adenylate cyclase system and isolated papillary muscle isometric function in noninfarcted left ventricular myocardium in rats after coronary artery ligation. In untreated rats with large myocardial infarction (MI), developed tension (DT) (3.0 +/- 0.7 versus 5.1 +/- 1.1 g/mm2), peak rate of tension rise (+dT/dt) (40.3 +/- 9.5 versus 71.2 +/- 12.0 g/mm2/sec), and peak rate of tension fall (-dT/dt) (24.4 +/- 5.0 versus 38.2 +/- 6.0 g/mm2/sec) were decreased (p < 0.05). In addition, DT, +dT/dt, and -dT/dt of untreated MI rats demonstrated an impaired response to isoproterenol stimulation compared with controls. beta-Adrenergic receptor density (Bmax) measured by [125I]iodocyanopindolol (ICYP) binding was decreased 23% after infarction (9.3 +/- 0.6 versus 12.0 +/- 1.8 fmol/mg protein [prot]) (p < 0.05); however, the dissociation constant (Kd) for ICYP was not changed (24.1 +/- 5.7 versus 33.2 +/- 12.1 pM). Adenylate cyclase activity in the presence of 10(-2) M MgCl2 was reduced (p < 0.05) in MI rats (30.3 +/- 10.8 versus 45.9 +/- 12.5 pmol cAMP/min/mg prot). Maximal isoproterenol (52.5 +/- 7.3 versus 79.9 +/- 10.0 pmol cAMP/min/mg prot), guanyl-5'-imidodiphosphate (GppNHp) (95 +/- 8 versus 141 +/- 25 pmol cAMP/min/mg prot) and forskolin (503 +/- 76 versus 753 +/- 157 pmol cAMP/min/mg prot) stimulation of adenylate cyclase was also decreased (p < 0.05). In addition, manganese-stimulated adenylate cyclase activity was depressed (p < 0.05) in MI rats compared with controls (23.5 +/- 2.8 versus 52.1 +/- 9.0 pmol cAMP/min/mg prot). Chronic propranolol treatment in MI rats improved DT (4.1 +/- 0.9 versus 3.0 +/- 0.7 g/mm2) and +dT/dt (54.4 +/- 11.3 versus 40.5 +/- 9.5 g/mm2/sec) (p < 0.05); however, isoproterenol-stimulated isometric function remained impaired. Propranolol treatment normalized Bmax (11.9 +/- 1.7 versus 9.3 +/- 0.6 fmol/mg prot) (p < 0.05), whereas adenylate cyclase activity remained depressed.

CONCLUSIONS

After large MI in rats, there is impaired papillary muscle function with decreased beta-adrenergic receptors and adenylate cyclase activity in the noninfarcted myocardium. Propranolol treatment improved basal isometric muscle function and beta-adrenergic receptor density in rats after myocardial infarction but did not improve adenylate cyclase activity or isoproterenol-stimulated muscle function. These data suggest that there is a primary defect in adenylate cyclase function that persists despite upregulation of receptors with propranolol treatment.

Contractility and stiffness of noninfarcted myocardium after coronary ligation in rats. Effects of chronic angiotensin converting enzyme inhibition

BACKGROUND

Previous studies have shown that global left ventricular function is depressed after myocardial infarction. However, little is known about the effects of myocardial infarction on contractility and the passive-elastic properties of residual myocardium.

METHODS AND RESULTS

We evaluated isometric function and passive myocardial stiffness in isolated, noninfarcted left ventricular papillary muscle from rats 6 weeks after sham operation or myocardial infarction. Maximal developed tension and peak rate of tension rise (+dT/dt) were significantly decreased in untreated rats with large myocardial infarction compared with controls (3.3 +/- 1.1 versus 4.3 +/- 0.6 g/mm2 and 49.5 +/- 17.5 versus 72.5 +/- 10.5 g/mm2/sec, respectively). Time to peak tension was prolonged (120 +/- 8 versus 102 +/- 4 msec) and myocardial stiffness was increased in untreated myocardial infarction rats compared with controls (35.2 +/- 4.9 versus 24.2 +/- 3.7). Rats with smaller myocardial infarctions differed from controls only with respect to a prolongation of time to peak tension. Papillary muscle myocyte cross-sectional area was increased by 44% (p less than 0.05), and myocardial hydroxyproline content was increased by 160% (p less than 0.05) in rats with large myocardial infarctions compared with controls. To determine whether treatment that improves left ventricular function after myocardial infarction also improves myocardial function, rats were treated with captopril beginning 3 weeks after myocardial infarction and continuing for 3 weeks. Treatment with captopril attenuated the prolongation in time to peak tension in the myocardial infarction rats; however, developed tension, +dT/dt, and muscle stiffness remained abnormal. Compared with untreated myocardial infarction rats, captopril-treated myocardial infarction rats had a 9% decrease in myocyte cross-sectional area (p = 0.1) but a persistent increase in myocardial collagen content. In summary, large myocardial infarction in rats causes contractile dysfunction, increased stiffness, myocyte hypertrophy, and increased collagen content in the residual noninfarcted myocardium. Treatment with captopril alters the process of cardiac remodeling and hypertrophy and improves one parameter of contractility in noninfarcted myocardium; however, myocardial collagen content and myocardial stiffness remain abnormal.

CONCLUSIONS

These findings suggest that angiotensin converting enzyme inhibition in the rat infarct model of heart failure improves global cardiac performance via combined effects on myocardial function and the peripheral circulation.

Rheumatic heart disease epidemiology. 3. The San Luis Valley prevalence study

After epidemiologic data had suggested the existence of a high-risk rheumatic fever (RF) region in Colorado, examination of 3,737 children in a careful prevalence study in that region, the San Luis Valley yielded 14 cases of rheumatic heart disease (RHD) for a prevalence rate of 3.7/1,000. This rate was significantly higher than the rate of 1.7/1,000 among Denver children of the same age screened by a similar method and followed for a similar period for ascertainment of diagnoses. Although the current high RHD risk in the San Luis Valley had been thought to be due to the relative impoverishment of this part of the state, the RHD and history-of-RF prevalence rates did not correlate with socioeconomic indices by county within the Valley as expected. An ethnic difference in RHD prevalence seen in Denver did not exist in the San Luis Valley, which led to speculation about (1) patterns of school attendance in small towns versus urban areas, and (2) the probability that the influence of poverty as an RHD-risk factor operates on a community rather than on a family or individual level.