Nagesh S. Anavekar

State-of-the-Art PaperCardiorenal Syndrome

The term cardiorenal syndrome (CRS) increasingly has been used without a consistent or well-accepted definition. To include the vast array of interrelated derangements, and to stress the bidirectional nature of heart-kidney interactions, we present a new classification of the CRS with 5 subtypes that reflect the pathophysiology, the time-frame, and the nature of concomitant cardiac and renal dysfunction. CRS can be generally defined as a pathophysiologic disorder of the heart and kidneys whereby acute or chronic dysfunction of 1 organ may induce acute or chronic dysfunction of the other. Type 1 CRS reflects an abrupt worsening of cardiac function (e.g., acute cardiogenic shock or decompensated congestive heart failure) leading to acute kidney injury. Type 2 CRS comprises chronic abnormalities in cardiac function (e.g., chronic congestive heart failure) causing progressive chronic kidney disease. Type 3 CRS consists of an abrupt worsening of renal function (e.g., acute kidney ischemia or glomerulonephritis) causing acute cardiac dysfunction (e.g., heart failure, arrhythmia, ischemia). Type 4 CRS describes a state of chronic kidney disease (e.g., chronic glomerular disease) contributing to decreased cardiac function, cardiac hypertrophy, and/or increased risk of adverse cardiovascular events. Type 5 CRS reflects a systemic condition (e.g., sepsis) causing both cardiac and renal dysfunction. Biomarkers can contribute to an early diagnosis of CRS and to a timely therapeutic intervention. The use of this classification can help physicians characterize groups of patients, provides the rationale for specific management strategies, and allows the design of future clinical trials with more accurate selection and stratification of the population under investigation.

Influence of Ejection Fraction on Cardiovascular Outcomes in a Broad Spectrum of Heart Failure Patients

Background— Left ventricular function is a principal determinant of cardiovascular risk in patients with heart failure. The growing number of patients with preserved systolic function heart failure underscores the importance of understanding the relationship between ejection fraction and risk. Methods and Results— We studied 7599 patients with a broad spectrum of symptomatic heart failure enrolled in the Candesartan in Heart failure: Assessment of Reduction in Mortality and morbidity (CHARM) Program. All patients were randomized to candesartan at a target dose of 32 mg once daily or matching placebo and followed up for a median of 38 months. We related left ventricular ejection fraction (LVEF), measured before randomization at the sites, to cardiovascular outcomes and causes of death. Mean LVEF in patients enrolled in CHARM was 38.8±14.9% (median LVEF 36%). Patients with lower LVEF tended to have higher baseline New York Heart Association class. The hazard ratio for all-cause mortality increased by 39% for every 10% reduction in ejection fraction below 45% (hazard ratio 1.39, 95% CI 1.32 to 1.46), with adjustment for baseline covariates. All-cause mortality, cardiovascular death, and all components of cardiovascular death declined with increasing ejection fraction until an ejection fraction of 45%, after which the risk of these outcomes remained relatively stable with increasing LVEF. The absolute change in rate per 100 patient-years for each 10% reduction in LVEF was greatest for sudden death and heart failure–related death. The effect of candesartan in reducing cardiovascular outcomes was consistent across LVEF categories. Conclusions— LVEF is a powerful predictor of cardiovascular outcome in heart failure patients across a broad spectrum of ventricular function. Nevertheless, once elevated to a range above 45%, ejection fraction does not further contribute to assessment of cardiovascular risk in heart failure patients.

Increase in Creatinine and Cardiovascular Risk in Patients with Systolic Dysfunction after Myocardial Infarction

Baseline renal function is a potent independent risk factor for adverse events after acute myocardial infarction (MI). Worsening renal function (WRF) has been shown to influence outcomes in the heart failure population, but its impact on cardiovascular risk in the post-MI period has not been well defined. For assessment of the prognostic importance of WRF, 2231 patients who had left ventricular dysfunction and were enrolled in the Survival and Ventricular Enlargement (SAVE) trial were studied. Patients were randomly assigned between 3 and 16 d (average 11 d) after acute MI to receive captopril or placebo; those with a serum creatinine of >2.5 mg/dl were excluded from SAVE. WRF was defined as an increase in creatinine of >0.3 mg/dl measured from baseline to 2 wk after randomization. The predictive value of WRF on cardiovascular morbidity and mortality was examined during 42 mo of follow-up. Paired serum creatinine measurements at baseline and 2 wk were available in 1854 patients. WRF occurred in 223 (12.0%) patients and was a stronger predictor of death (hazard ratio [HR] 1.46; 95% confidence interval [CI] 1.05 to 2.02) than baseline creatinine (HR 1.31; 95% CI 1.01 to 1.70). WRF also showed an increased risk for cardiovascular death (HR 1.62; 95% CI 1.14 to 2.30) and the composite end point (HR 1.32; 95% CI 1.03 to 1.70). When stratified by treatment, 104 (5.7%) and 116 (6.4%) patients with WRF in the placebo and captopril groups had no significant association between treatment group and WRF (P = 0.38). The risk for death associated with WRF was HR 1.63 (95% CI 1.05 to 2.52) in the placebo group compared with HR 1.33 (95% CI 0.81 to 2.21) in the captopril group (P = 0.49 for interaction). WRF as early as 2 wk after MI was not uncommon (12.0%) and was associated with increased mortality in patients without renal dysfunction at baseline. Patients who received captopril did not demonstrate more WRF than patients who received placebo. Monitoring serum creatinine in patients during the first few weeks after MI may help to identify those who are at highest risk and guide effective long-term therapeutic choices.

Usefulness of Right Ventricular Fractional Area Change to Predict Death, Heart Failure, and Stroke Following Myocardial Infarction (from the VALIANT ECHO Study)

Severe right ventricular dysfunction independent of left ventricular ejection fraction increased the risk of heart failure (HF) and death after myocardial infarction (MI). The association between right ventricular function and other clinical outcomes after MI was less clear. Two-dimensional echocardiograms were obtained in 605 patients with left ventricular dysfunction and/or clinical/radiologic evidence of HF from the VALIANT echocardiographic substudy (mean 5.0 +/- 2.5 days after MI). Clinical outcomes included all-cause mortality, cardiovascular (CV) death, sudden death, HF, and stroke. Baseline right ventricular function was measured in 522 patients using right ventricular fractional area change (RVFAC) and was related to clinical outcomes. Mean RVFAC was 41.9 +/- 4.3% (range 19.2% to 53.1%). The incidence of clinical events increased with decreasing RVFAC. After adjusting for 11 covariates, including age, ejection fraction, and Killips classification, decreased RVFAC was independently associated with increased risk of all-cause mortality (hazard ratio [HR] 1.61, 95% confidence interval [CI] 1.31 to 1.98), CV death (HR 1.62, 95% CI 1.30 to 2.01), sudden death (HR 1.79, 95% CI 1.26 to 2.54), HF (HR 1.48, 95% CI 1.17 to 1.86), and stroke (HR 2.95, 95% CI 1.76 to 4.95), but not recurrent MI. Each 5% decrease in baseline RVFAC was associated with a 1.53 (95% CI 1.24 to 1.88) increased risk of fatal and nonfatal CV outcomes. In conclusion, decreased right ventricular systolic function is a major risk factor for death, sudden death, HF, and stroke after MI.

Impact of Prior Antiplatelet Therapy on Risk of Embolism in Infective Endocarditis

BACKGROUND Embolism is a dreaded complication of infective endocarditis (IE). Currently, antimicrobial therapy is the only medical intervention proven to decrease the risk of embolism associated with IE. We hypothesized that, because platelet aggregation is operative in the pathogenesis of vegetation formation, embolism associated with IE should occur less frequently among patients who have received prior, continuous daily antiplatelet therapy for noninfectious reasons. METHODS We studied a retrospective cohort of adult patients with a diagnosis of IE who presented to the Mayo Clinic (Rochester, MN) during 1980-1998. The cohort was divided into 2 groups on the basis of whether they had received continuous daily antiplatelet therapy for at least 6 months prior to the time of hospitalization for IE. Antiplatelet therapy included aspirin, dipyridamole, clopidogrel, ticlopidine, or any of combination of these agents. The primary end point was a symptomatic embolic event that occurred prior to or during hospitalization. Multivariable logistic regression was used to assess the impact of continuous daily antiplatelet therapy on risk of symptomatic emboli associated with IE. RESULTS One hundred forty-seven (24.5%) of 600 patients experienced a symptomatic embolic event; the most common embolic manifestation was stroke (in 48.2% of patients). Embolic events occurred significantly less often among those who had received prior, continuous daily antiplatelet therapy (12.0% of patients who had received therapy vs. 27.8% patients who had not receive therapy; P<.001). After adjustment for several covariates known to influence both risk of embolism and propensity for antiplatelet use, the adjusted odds ratio for a symptomatic embolic event was 0.36 (95% confidence interval, 0.19-0.68; P=.002) for patients receiving continuous daily antiplatelet therapy. CONCLUSIONS The risk of symptomatic emboli associated with IE was reduced in patients who received continuous daily antiplatelet therapy before onset of IE.

Characterization of Microvascular Dysfunction After Acute Myocardial Infarction by Cardiovascular Magnetic Resonance First-Pass Perfusion and Late Gadolinium Enhancement Imaging

PURPOSE While both first-pass perfusion and late gadolinium enhancement by cardiovascular magnetic resonance (CMR) can assess coronary microvascular status in acute myocardial infarction (AMI), there are only limited data on their respective diagnostic utility. We aim to evaluate: the utility of first-pass perfusion and late gadolinium enhancement imaging in the detection and quantification of microvascular dysfunction after reperfused acute myocardial infarction, using TIMI frame count (TIMI FC) as the reference standard of microvascular assessment; and their relationship with infarct size and ventricular function. METHODS First-pass perfusion and late gadolinium enhancement imaging were performed in 25 consecutive AMI patients (84% men, age 58 +/- 10) within 72 h of successful reperfusion. We assessed the myocardial extent of microvascular dysfunction using the size of the perfusion defect on first-pass perfusion (PD%) and the hypoenhanced core region within late gadolinium enhancement (MDEcore%). PD%, MDEcore%, and TIMI FC were analyzed independently of each other and with blinding to clinical data. We adjusted PD% and MDEcore% to the myocardial mass subtended by the infarct-related artery according to the 16-segment model. RESULTS Median infarct size involved 13.9% (interquartile range: 8.5 to 22.2%) of the left ventricle and median left ventricular ejection fraction was 52% (interquartile range: 43 to 61%). PD% demonstrated evidence of microvascular dysfunction more frequently (84% vs. 36% of patients, p < 0.002) and involved a larger myocardial extent (23.5 +/- 17.5% vs. 3.5 +/- 7.7%, p < 0.001) compared to MDEcore%. PD% had strong correlations with TIMI FC (Spearman rho = 0.62, p < 0.001) and infarct size (rho = 0.64, p < 0.001), and a moderate correlation with LVEF (rho = -0.39, p = 0.055). MDEcore% also correlated with TIMI FC (rho = 0.54, p = 0.005) and infarct size (rho = 0.52, p < 0.01) but not with LVEF (p = NS). CONCLUSIONS PD% appeared to provide a stronger noninvasive assessment of the microvascular function than MDEcore% and correlated well with prognostic markers such as left ventricular ejection fraction and infarct size. Future studies should consider quantitative analyses of both first-pass perfusion and late gadolinium enhancement imaging in the evaluation of novel therapies targeted to the microvasculature of the infarct-related artery.

Angiotensin II receptor blockade and ventricular remodelling

Cardiac remodelling is the expression of molecular, cellular and interstitial changes in response to cardiac injury, manifesting as adverse alterations in the size, shape and function of the ventricle. Several clinical studies have documented significant elevations in the levels of renin, angiotensin II (Ang II) and aldosterone attending acute myocardial infarction and/or congestive heart failure. Similar to catecholamines, markedly elevated activity of the renin-angiotensin-aldosterone system (RAAS) is associated with poor prognosis. The effects of Ang II upon cardiac tissue are related to two primary receptors, Ang II type 1 (AT 1) and Ang II type 2 (AT2). The AT1-receptor appears to mediate many of the deleterious effects of chronic RAAS activity, while the AT2-receptor is increasingly shown to have potential cardioprotective effects. Attenuating the deleterious effects of sustained Ang II stimulation can be achieved by direct inhibition of angiotensin-converting enzyme (ACE) and/or direct antagonism of AT receptors. ACE inhibition reduces left ventricular (LV) volumes, retards the progression of LV dilatation and hypertrophy and increases systolic function in systolic dysfunction. By blocking at the receptor level, Ang II receptor blockers (ARBs) provide an alternative and more direct approach to inhibiting the effects of Ang II; however, data relating to their effects upon ventricular remodelling, whether used in isolation or in combination with ACE inhibitors (ACE-Is), are less convincing. Data arising from several recent clinical trials suggest that simultaneous use of ACE-Is and ARBs maybe of more benefit in attenuating ventricular remodelling than either agent alone.

Comparison of renal function and cardiovascular risk following acute myocardial infarction in patients with and without diabetes mellitus.

Renal dysfunction is an independent risk factor for cardiovascular (cv) disease and its associated complications. Diabetes mellitus (dm) is a common cause of renal dysfunction. Whether the presence or absence of dm modifies the relation between renal dysfunction and cv disease is unclear. The valiant trial identified 14,527 patients with acute myocardial infarction complicated by either clinical or radiologic signs of heart failure and/or left ventricular dysfunction for whom baseline creatinine was measured. Patients were randomly assigned to receive captopril, valsartan, or both. Glomerular filtration rate (gfr) was estimated using the 4-component modification of diet in renal disease equation. Using multivariable cox proportional modeling, the relation of overall mortality and composite cardiovascular events with estimated gfr (egfr) between patients with and without dm was compared. Mean egfrs were 66.8 +/- 22.0 and 71.2 +/- 21.0 ml/min/1.73 m2 for patients with (n = 3,358) and without dm (n = 11,169), respectively. The likelihood of experiencing death or the composite end point was higher in patients with than without dm for each level of renal function. the augmentation in risk of cv events based on reduced renal function was similar between groups. Each decrease in egfr by 10 units was associated with hazards of 1.09 (95% confidence interval 1.06 to 1.12, p <0.001) in patients with dm and 1.08 (95% confidence interval 1.06 to 1.10, p <0.001) in patients without dm for risk of fatal and nonfatal cv outcomes independent of treatment assignment. In conclusion, although dm is associated with higher risk of renal dysfunction and adverse cv outcomes, patients without dm had a relation between renal function and cv risk similar to that for patients with dm after high-risk acute myocardial infarction.

NEPHROGENIC SYSTEMIC FIBROSIS ASSOCIATED WITH GADOLINIUM‐CONTAINING CONTRAST MEDIA ADMINISTRATION IN PATIENTS WITH REDUCED GLOMERULAR FILTRATION RATE

To the Editor: We write to highlight the recently described association between gadolinium-containing contrast agents and nephrogenic systemic fibrosis (NSF, previously also known as nephrogenic fibrosing dermopathy). Magnetic resonance imaging (MRI) frequently requires the administration of gadolinium as a contrast agent. Gadolinium-containing contrast agents are occasionally used as an alternative to iodine-based angiographic contrast media in the setting of iodine allergy or significant renal impairment. Nephrogenic systemic fibrosis is a rare condition observed in patients with kidney impairment who are generally close to (eGFR < 15 mL/min) or requiring dialysis, and in patients with functioning kidney transplants. The precise incidence of this serious disease requires further studies, but nearly 200 cases have been reported worldwide. The typical presentation is well-defined, erythematous, indurated plaques on the limbs and trunk, and the course is typically progressive, with joint contractures, physical disability and even death. Internal organ fibrosis also occurs, involving heart, lung, liver, skeletal muscle and meninges. Short of improving renal function by transplantation, there is currently no established treatment for NSF, although a number of therapies have been used with varying success. Although the cause of NSF remains unclear, reports of the association with renal impairment and gadolinium infusion are published. Further, it has been considered by the United States Food and Drug Administration, which has issued a public health advisory recommending gadoliniumcontaining contrast agents be used only if clearly necessary in patients with advanced kidney failure and that prompt dialysis is instituted in patients with advanced kidney failure who receive gadolinium-containing contrast agents. Austin Health has reassessed its practice with regards to gadolinium-containing contrast agents. The standard pre-MRI questionnaire now acknowledges the presence of kidney impairment or kidney transplantation or the requirement of dialysis in the standard pre-MRI questionnaire, while restricting the use of gadolinium in patients with kidney impairment to strong clinical indications, which outweigh the risk of NSF. This risk assessment is difficult because the precise incidence of NSF is unknown. The authors have introduced this conservative approach despite the fact that we are not aware of any cases of NSF notwithstanding 97 dialysis patients receiving 146 doses of gadolinium-containing contrast agents at our institution. In conclusion, although a causal link between gadolinium and NSF has not yet been firmly established, we wish to urge caution in the usage of gadolinium in patients with impaired kidney function and consider that further studies should be supported in this area.

Therapeutic interventions for heart failure with preserved ejection fraction: A summary of current evidence

Heart failure with preserved ejection fraction (HFPEF) is common and represents a major challenge in cardiovascular medicine. Most of the current treatment of HFPEF is based on morbidity benefits and symptom reduction. Various pharmacological interventions available for heart failure with reduced ejection fraction have not been supported by clinical studies for HFPEF. Addressing the specific aetiology and aggressive risk factor modification remain the mainstay in the treatment of HFPEF. We present a brief overview of the currently recommended therapeutic options with available evidence.