Peter A. McCullough

Kidney Disease as a Risk Factor for Development of Cardiovascular Disease A Statement From the American Heart Association Councils on Kidney in Cardiovascular Disease, High Blood Pressure Research, Clinical Cardiology, and Epidemiology and Prevention

Chronic kidney disease1 (CKD) is a worldwide public health problem. In the United States, there is a rising incidence and prevalence of kidney failure, with poor outcomes and high cost. The number of individuals with kidney failure treated by dialysis and transplantation exceeded 320 000 in 1998 and is expected to surpass 650 000 by 2010.1,2 There is an even higher prevalence of earlier stages of CKD (Table 1).1,3 Kidney failure requiring treatment with dialysis or transplantation is the most visible outcome of CKD. However, cardiovascular disease (CVD) is also frequently associated with CKD, which is important because individuals with CKD are more likely to die of CVD than to develop kidney failure,4 CVD in CKD is treatable and potentially preventable, and CKD appears to be a risk factor for CVD. In 1998, the National Kidney Foundation (NKF) Task Force on Cardiovascular Disease in Chronic Renal Disease issued a report emphasizing the high risk of CVD in CKD.5 This report showed that there was a high prevalence of CVD in CKD and that mortality due to CVD was 10 to 30 times higher in dialysis patients than in the general population (Figure 1 and Table 2).6–18 The task force recommended that patients with CKD be considered in the “highest risk group” for subsequent CVD events and that treatment recommendations based on CVD risk stratification should take into account the highest-risk status of patients with CKD. View this table: TABLE 1. Stages of CKD Figure 1. Cardiovascular mortality defined by death due to arrhythmias, cardiomyopathy, cardiac arrest, myocardial infarction, atherosclerotic heart disease, and pulmonary edema in general population (GP; National Center for Health Statistics [NCHS] multiple cause of mortality data files International Classification of Diseases, 9th Revision [ICD 9] codes 402, 404, 410 to 414, and …

Acute Renal Failure After Coronary Intervention: Incidence, Risk Factors, and Relationship to Mortality

PURPOSE This study set out to define the incidence, predictors, and mortality related to acute renal failure (ARF) and acute renal failure requiring dialysis (ARFD) after coronary intervention. PATIENTS AND METHODS Derivation-validation set methods were used in 1,826 consecutive patients undergoing coronary intervention with evaluation of baseline creatinine clearance (CrCl), diabetic status, contrast exposure, postprocedure creatinine, ARF, ARFD, in-hospital mortality, and long-term survival (derivation set). Multiple logistic regression was used to derive the prior probability of ARFD in a second set of 1,869 consecutive patients (validation set). RESULTS The incidence of ARF and ARFD was 144.6/1,000 and 7.7/1,000 cases respectively. The cutoff dose of contrast below which there was no ARFD was 100 mL. No patient with a CrCl > 47 mL/min developed ARFD. These thresholds were confirmed in the validation set. Multivariate analysis found CrCl [odds ratio (OR) = 0.83, 95% confidence interval (CI) 0.77 to 0.89, P <0.00001], diabetes (OR = 5.47, 95% CI 1.40 to 21.32, P = 0.01), and contrast dose (OR = 1.008, 95% CI 1.002 to 1.013, P = 0.01) to be independent predictors of ARFD. Patients in the validation set who underwent dialysis had a predicted prior probability of ARFD of between 0.07 and 0.73. The in-hospital mortality for those who developed ARFD was 35.7% and the 2-year survival was 18.8%. CONCLUSION The occurrence of ARFD after coronary intervention is rare (<1%) but is associated with high in-hospital mortality and poor long-term survival. Individual patient risk can be estimated from calculated CrCl, diabetic status, and expected contrast dose prior to a proposed coronary intervention.

Contrast-Induced Acute Kidney Injury

Cardiac angiography and coronary/vascular interventions depend on iodinated contrast media and consequently pose the risk of contrast-induced acute kidney injury (AKI). This is an important complication that accounts for a significant number of cases of hospital-acquired renal failure, with adverse effects on prognosis and health care costs. The epidemiology and pathogenesis of contrast-induced AKI, baseline renal function measurement, risk assessment, identification of high-risk patients, contrast medium use, and preventive strategies are discussed in this report. An advanced algorithm is suggested for the risk stratification and management of contrast-induced AKI as it relates to patients undergoing cardiovascular procedures. Contrast-induced AKI is likely to remain a significant challenge for cardiologists in the future because the patient population is aging and chronic kidney disease and diabetes are becoming more common.

A prospective randomized trial of prevention measures in patients at high risk for contrast nephropathy ☆: Results of the P.R.I.N.C.E. study

Objectives This study was done to test the hypothesis that a forced diuresis with maintenance of intravascular volume after contrast exposure would reduce the rate of contrast-induced renal injury. Background We have previously shown a graded relationship with the degree of postprocedure renal failure and the probability of in-hospital death in patients undergoing percutaneous coronary intervention. Earlier studies of singular prevention strategies (atrial natriuretic factor, loop diuretics, dopamine, mannitol) have shown no clear benefit across a spectrum of patients at risk. Methods A prospective, randomized, controlled, single-blind trial was conducted where 98 participants were randomized to forced diuresis with intravenous crystalloid, furosemide, mannitol (if pulmonary capillary wedge pressure <20 mm Hg), and low-dose dopamine (n = 43) versus intravenous crystalloid and matching placebos (n = 55). Results The groups were similar with respect to baseline serum creatinine (2.44 ± 0.80 and 2.55 ± 0.91 mg/dl), age, weight, diabetic status, left ventricular function, degree of prehydration, contrast volume and ionicity, and extent of peripheral vascular disease. The forced diuresis resulted in higher urine flow rate (163.26 ± 54.47 vs. 122.57 ± 54.27 ml/h) over the 24 h after contrast exposure (p = 0.001). Two participants in the experimental arm versus five in the control arm required dialysis, with all seven cases having measured flow rates <145 ml/h in the 24 h after the procedure. The mean individual change in serum creatinine at 48 h, the primary end point, was 0.48 ± 0.86 versus 0.51 ± 0.87, in the experimental and control arms, respectively, p = 0.87. There were no differences in the rates of renal failure across six definitions of renal failure by intent-to-treat analysis. However, in all participants combined, the rise in serum creatinine was related to the degree of induced diuresis after controlling for baseline renal function, r = −0.36, p = 0.005. The rates of renal failure in those with urine flow rates greater than 150 ml/h in the postprocedure period were significantly lower, 8/37 (21.6%) versus 28/61 (45.9%), p = 0.03. Conclusions Forced diuresis with intravenous crystalloid, furosemide, and mannitol if hemodynamics permit, beginning at the start of angiography provides a modest benefit against contrast-induced nephropathy provided a high urine flow rate can be achieved.

Early Invasive vs Conservative Treatment Strategies in Women and Men With Unstable Angina and Non–ST-Segment Elevation Myocardial Infarction: A Meta-analysis

CONTEXT Although an invasive strategy is frequently used in patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS), data from some trials suggest that this strategy may not benefit women. OBJECTIVE To conduct a meta-analysis of randomized trials to compare the effects of an invasive vs conservative strategy in women and men with NSTE ACS. DATA SOURCES Trials were identified through a computerized literature search of the MEDLINE and Cochrane databases (1970-April 2008) using the search terms invasive strategy, conservative strategy, selective invasive strategy, acute coronary syndromes, non-ST-elevation myocardial infarction, and unstable angina. STUDY SELECTION Randomized clinical trials comparing an invasive vs conservative treatment strategy in patients with NSTE ACS. DATA EXTRACTION The principal investigators for each trial provided the sex-specific incidences of death, myocardial infarction (MI), and rehospitalization with ACS through 12 months of follow-up. DATA SYNTHESIS Data were combined across 8 trials (3075 women and 7075 men). The odds ratio (OR) for the composite of death, MI, or ACS for invasive vs conservative strategy in women was 0.81 (95% confidence interval [CI], 0.65-1.01; 21.1% vs 25.0%) and in men was 0.73 (95% CI, 0.55-0.98; 21.2% vs 26.3%) without significant heterogeneity between sexes (P for interaction = .26). Among biomarker-positive women, an invasive strategy was associated with a 33% lower odds of death, MI, or ACS (OR, 0.67; 95% CI, 0.50-0.88) and a nonsignificant 23% lower odds of death or MI (OR, 0.77; 95% CI, 0.47-1.25). In contrast, an invasive strategy was not associated with a significant reduction in the triple composite end point in biomarker-negative women (OR, 0.94; 95% CI, 0.61-1.44; P for interaction = .36) and was associated with a nonsignificant 35% higher odds of death or MI (OR, 1.35; 95% CI, 0.78-2.35; P for interaction = .08). Among men, the OR for death, MI, or ACS was 0.56 (95% CI, 0.46-0.67) if biomarker-positive and 0.72 (95% CI, 0.51-1.01) if biomarker-negative (P for interaction = .09). CONCLUSIONS In NSTE ACS, an invasive strategy has a comparable benefit in men and high-risk women for reducing the composite end point of death, MI, or rehospitalization with ACS. In contrast, our data provide evidence supporting the new guideline recommendation for a conservative strategy in low-risk women.

Risks associated with renal dysfunction in patients in the coronary care unit

OBJECTIVES The purpose of this study was to quantify the impact of baseline renal dysfunction on morbidity and mortality in patients in the coronary care unit (CCU). BACKGROUND The presence of renal dysfunction is an established independent predictor of survival after acute myocardial infarction and revascularization procedures. METHODS We analyzed a prospective CCU registry of 12,648 admissions by 9,557 patients over eight years at a single, tertiary center. Admission serum creatinine was available in 9,544 patients. Those not on long-term dialysis were classified into quartiles of corrected creatinine clearance, with cut-points of 46.2, 63.1 and 81.5 ml/min per 72 kg. Dialysis patients (n = 527) were considered as a fifth comparison group. RESULTS Baseline characteristics, including older age, African-American race, diabetes, hypertension, previous coronary disease and heart failure, were incrementally more common across increasing renal dysfunction strata. There were graded increases in the relative risk for atrial and ventricular arrhythmias, heart block, asystole, development of pulmonary congestion, acute mitral regurgitation and cardiogenic shock across the risk strata. Survival analysis demonstrated an early mortality hazard for those with renal dysfunction, but not on dialysis, for the first 60 months, followed by graded decrements in survival across increasing renal dysfunction strata. CONCLUSIONS Baseline renal function is a powerful predictor of short- and long-term events in the CCU population. There is an early hazard for in-hospital and postdischarge mortality for those with a corrected creatinine clearance <46.2 ml/min per kg, but not on dialysis.

Bariatric Surgery and Cardiovascular Risk Factors

The rate of obesity is rising logarithmically, especially in those with severe obesity (body mass index [BMI] >40 kg/m2). Cardiologists, endocrinologists, internists, family practitioners, and most healthcare professionals are increasingly confronted with the severely obese patient and with postoperative bariatric patients because obesity is associated with significant morbidity and increased mortality. In addition, more adolescents these days are severely obese. Substantial long-term successes of lifestyle modifications and drug therapy have been disappointing in this population. The National Institutes of Health has suggested that surgical therapy be proposed to those patients with BMI >40 kg/m2 or >35 kg/m2 with serious obesity-related comorbidities such as systemic hypertension, type 2 diabetes mellitus, and obstructive sleep apnea. When indicated, surgical intervention leads to significant improvements in decreasing excess weight and comorbidities that can be maintained over time. These include diabetes mellitus, dyslipidemia, liver disease, systemic hypertension, obstructive sleep apnea, and cardiovascular dysfunction. Recent prospective, nonrandomized, observational, or case-control population studies have also shown bariatric surgery to prolong survival in the severely obese. Different types of bariatric procedures are being performed. Historically, operative mortality was between 0.1% and 2.0% with more recent data not exceeding 1%. Early complications include pulmonary embolus (0.5%), anastomotic leaks (1.0% to 2.5%), and bleeding (1.0%). Late complications include anastomotic stricture, anastomotic ulcers, hernias, band slippage, and behavioral maladaptation. The number of bariatric operations being performed is increasing tremendously as a result of increasing medical need and the evolution of safer surgical techniques and guidelines. Currently, bariatric surgery should be reserved for patients who have severe obesity in whom efforts at medical therapy have failed and an acceptable operative risk is present. The terms overweight, obese, and severe obesity refer to a clinical continuum. Excess adiposity should be considered a chronic disease that has serious health consequences. An …

Cardiorenal Syndrome Type 1: Pathophysiological Crosstalk Leading to Combined Heart and Kidney Dysfunction in the Setting of Acutely Decompensated Heart Failure

Cardiorenal syndrome (CRS) type 1 is characterized as the development of acute kidney injury (AKI) and dysfunction in the patient with acute cardiac illness, most commonly acute decompensated heart failure (ADHF). There is evidence in the literature supporting multiple pathophysiological mechanisms operating simultaneously and sequentially to result in the clinical syndrome characterized by a rise in serum creatinine, oliguria, diuretic resistance, and in many cases, worsening of ADHF symptoms. The milieu of chronic kidney disease has associated factors including obesity, cachexia, hypertension, diabetes, proteinuria, uremic solute retention, anemia, and repeated subclinical AKI events all work to escalate individual risk of CRS in the setting of ADHF. All of these conditions have been linked to cardiac and renal fibrosis. In the hospitalized patient, hemodynamic changes leading to venous renal congestion, neurohormonal activation, hypothalamic-pituitary stress reaction, inflammation and immune cell signaling, systemic endotoxemic exposure from the gut, superimposed infection, and iatrogenesis all contribute to CRS type 1. The final common pathway of bidirectional organ injury appears to be cellular, tissue, and systemic oxidative stress that exacerbate organ function. This review explores in detail the pathophysiological pathways that put a patient at risk and then effectuate the vicious cycle now recognized as CRS type 1.

A prospective randomized trial of triage angiography in acute coronary syndromes ineligible for thrombolytic therapy: Results of the medicine versus angiography in thrombolytic exclusion (MATE) trial

OBJECTIVES The purpose of this study was to determine if early triage angiography with revascularization, if indicated, favorably affects clinical outcomes in patients with suspected acute myocardial infarction who are ineligible for thrombolysis. BACKGROUND The majority of patients with acute myocardial infarction and other acute coronary syndromes are considered ineligible for thrombolysis and therefore are not afforded the opportunity for early reperfusion. METHODS This multicenter, prospective, randomized trial evaluated in a controlled fashion the outcomes following triage angiography in acute coronary syndromes ineligible for thrombolytic therapy. Eligible patients (n=201) with <24 h of symptoms were randomized to early triage angiography and subsequent therapies based on the angiogram versus conventional medical therapy consisting of aspirin, intravenous heparin, nitroglycerin, beta-blockers, and analgesics. RESULTS In the triage angiography group, 109 patients underwent early angiography and 64 (58%) received revascularization, whereas in the conservative group, 54 (60%) subsequently underwent nonprotocol angiography in response to recurrent ischemia and 33 (37%) received revascularization (p=0.004). The mean time to revascularization was 27+/-32 versus 88+/-98 h (p=0.0001) and the primary endpoint of recurrent ischemic events or death occurred in 14 (13%) versus 31 (34%) of the triage angiography and conservative groups, respectively (45% risk reduction, 95% CI 27-59%, p=0.0002). There were no differences between the groups with respect to initial hospital costs or length of stay. Long-term follow-up at a median of 21 months revealed no significant differences in the endpoints of late revascularization, recurrent myocardial infarction, or all-cause mortality. CONCLUSIONS Early triage angiography in patients with acute coronary syndromes who are not eligible for thrombolytics reduced the composite of recurrent ischemic events or death and shortened the time to definitive revascularization during the index hospitalization. Despite more frequent early revascularization after triage angiography, we found no long-term benefit in cardiac outcomes compared with conservative medical therapy with revascularization prompted by recurrent ischemia.

Bedside B-Type natriuretic peptide in the emergency diagnosis of heart failure with reduced or preserved ejection fraction

OBJECTIVES This study examines B-type natriuretic peptide (BNP) levels in patients with systolic versus non-systolic dysfunction presenting with shortness of breath. BACKGROUND Preserved systolic function is increasingly common in patients presenting with symptoms of congestive heart failure (CHF) but is still difficult to diagnose. METHODS The Breathing Not Properly Multinational Study was a seven-center, prospective study of 1,586 patients who presented with acute dyspnea and had BNP measured upon arrival. A subset of 452 patients with a final adjudicated diagnosis of CHF who underwent echocardiography within 30 days of their visit to the emergency department (ED) were evaluated. An ejection fraction of greater than 45% was defined as non-systolic CHF. RESULTS Of the 452 patients with a final diagnosis of CHF, 165 (36.5%) had preserved left ventricular function on echocardiography, whereas 287 (63.5%) had systolic dysfunction. Patients with non-systolic heart failure (NS-CHF) had significantly lower BNP levels than those with systolic heart failure (S-CHF) (413 pg/ml vs. 821 pg/ml, p < 0.001). As the severity of heart failure worsened by New York Heart Association class, the percentage of S-CHF increased, whereas the percentage of NS-CHF decreased. When patients with NS-CHF were compared with patients without CHF (n = 770), a BNP value of 100 pg/ml had a sensitivity of 86%, a negative predictive value of 96%, and an accuracy of 75% for detecting abnormal diastolic dysfunction. Using Logistic regression to differentiate S-CHF from NS-CHF, BNP entered first as the strongest predictor followed by oxygen saturation, history of myocardial infarction, and heart rate. CONCLUSIONS We conclude that NS-CHF is common in the setting of the ED and that differentiating NS-CHF from S-CHF is difficult in this setting using traditional parameters. Whereas BNP add modest discriminatory value in differentiating NS-CHF from S-CHF, its major role is still the separation of patients with CHF from those without CHF.