Nevin Katz

Atrial pacing for the prevention of atrial fibrillation after cardiovascular surgery.

OBJECTIVE The purpose of this study was to determine the efficacy of atrial pacing in the prevention of atrial fibrillation following cardiovascular surgery. BACKGROUND Although pharmacologic therapy has been used to help prevent postoperative atrial fibrillation, it suffers from limited efficacy and adverse effects. In the nonoperative setting, novel pacing strategies have been shown to reduce recurrences of atrial fibrillation and prolong arrhythmia-free periods in patients with paroxysmal atrial arrhythmias. METHODS A total of 154 patients (115 men; mean age, 65 +/- 10 years; ejection fraction, 53 +/- 10%) undergoing cardiac surgery (coronary artery bypass surgery, 88.3%; aortic valve replacement, 4.5%; coronary bypass + aortic valve replacement, 7.1%) had right and left atrial epicardial pacing electrodes placed at the time of surgery. Patients were randomized to either no pacing, right atrial (RAP), left atrial (LAP) or biatrial pacing (BAP) for 72 h after surgery. Beta-adrenergic blocking agents were administered concurrently to all patients following surgery. RESULTS There was a reduction in the incidence of postoperative atrial fibrillation from 37.5% in patients receiving no postoperative pacing to 17% (p < 0.005) in patients assigned to one of the three pacing strategies. The length of hospital stay was reduced by 22% from 7.8 +/- 3.7 days to 6.1 +/- 2.3 days (p = 0.003) in patients assigned to postoperative atrial pacing. The incidence of atrial fibrillation was lower in each of the paced groups (RAP, 8%; LAP, 20%; BAP, 26%) compared with patients who did not receive postoperative pacing (37.5%). CONCLUSION Postoperative atrial pacing, in conjunction with beta-blockade, significantly reduced both the incidence of atrial fibrillation and the length of hospital stay following cardiovascular surgery. Additional studies are needed to determine the most effective anatomic pacing site.

Early diagnosis of acute kidney injury: the promise of novel biomarkers.

The incidence of acute kidney injury (AKI) formerly referred to as acute renal failure (ARF) is increasing to epidemic proportions. Development of AKI portends excessive morbidity and mortality. AKI is associated with prolonged hospital stay, increased healthcare costs and high mortality especially in critically ill patients. The mortality rate has remained largely unchanged for many decades. Delay in the diagnosis of AKI using conventional biomarkers like urine output and serum creatinine has been one of the important obstacles in applying effective early interventions. Several new biomarkers are being evaluated in a quest for early diagnosis of AKI, among which neutrophil gelatinase-associated lipocalin (NGAL) appears to be one of the most promising. This review summarizes the recent literature on these biomarkers.

Epidemiology of cardio-renal syndromes: workgroup statements from the 7th ADQI Consensus Conference

Sean M. Bagshaw, Dinna N. Cruz, Nadia Aspromonte, Luciano Daliento, Federico Ronco, Geoff Sheinfeld, Stefan D. Anker, Inder Anand, Rinaldo Bellomo, Tomas Berl, Ilona Bobek, Andrew Davenport, Mikko Haapio, Hans Hillege, Andrew House, Nevin Katz, Alan Maisel, Sunil Mankad, Peter McCullough, Alexandre Mebazaa, Alberto Palazzuoli, Piotr Ponikowski, Andrew Shaw, Sachin Soni, Giorgio Vescovo, Nereo Zamperetti, Pierluigi Zanco, Claudio Ronco and for the Acute Dialysis Quality Initiative (ADQI) Consensus Group

Cardiorenal Syndromes: An Executive Summary from the Consensus Conference of the Acute Dialysis Quality Initiative (ADQI)

The cardiorenal syndrome (CRS) is a disorder of the heart and kidneys whereby acute or chronic dysfunction in one organ may induce acute or chronic dysfunction of the other. The general definition has been expanded into five subtypes reflecting the primacy of organ dysfunction and the time-frame of the syndrome: CRS type 1 = acute worsening of heart function leading to kidney injury and/or dysfunction; CRS type 2 = chronic abnormalities in heart function leading to kidney injury or dysfunction; CRS type 3 = acute worsening of kidney function leading to heart injury and/or dysfunction; CRS type 4 = chronic kidney disease leading to heart injury, disease and/or dysfunction, and CRS type 5 = systemic conditions leading to simultaneous injury and/or dysfunction of heart and kidney. Different pathophysiological mechanisms are involved in the combined dysfunction of heart and kidney in these five types of the syndrome.

Inhibition of transplant coronary arteriosclerosis in rabbits by chronic estradiol treatment is associated with abolition of MHC class II antigen expression

BACKGROUND Accelerated coronary arteriosclerosis is a major complication in long-term survivors of cardiac transplantation. Estrogen prevents transplant arteriosclerosis in experimental cardiac and aortic allografts and may act by an immune mechanism. METHODS AND RESULTS New Zealand White rabbits immunosuppressed with cyclosporine were recipients of cardiac allografts from Dutch Belted rabbits. The recipients received either estradiol or placebo daily until they were killed 6 weeks later. Histological cross sections of the cardiac allograft were used for quantification of major histocompatibility complex (MHC) class II antigen expression, T lymphocytes, and macrophages by immunohistochemistry using monoclonal antibodies. MHC class II antigen expression was not detectable in allograft coronary arteries from any of the estradiol-treated recipients, whereas this antigen expression was present in the allograft coronary arteries from all the placebo-treated recipients. Macrophage and lymphocyte infiltration of the allograft coronary artery myointima was significantly less frequent in the estradiol-treated group. Rejection was moderate but slightly less in the estradiol-treated group. These findings were associated with a 60% decrease in allograft coronary artery myointimal thickening (determined by morphometry) in the estradiol-treated compared with the placebo-treated group. CONCLUSIONS Estradiol treatment of cardiac allograft recipients abolishes MHC class II antigen expression in the coronary arteries and decreases macrophage infiltration in all three layers of the vessel wall, whereas T-lymphocyte infiltration is decreased only in the myointima. These findings are associated with estradiol inhibition of myointimal proliferation. Thus, estradiol treatment may have a beneficial effect on graft arteriosclerosis through immune mechanisms.

Cardiac Operations in Patients Aged 70 Years and Over: Mortality, Length of Stay, and Hospital Charge

BACKGROUND With emphasis today on cost containment in health care, the results and costs of cardiac operations in elderly patients are being scrutinized. METHODS Our computerized database was used to obtain the characteristics of patients undergoing cardiac operations from January 1990 to July 1994. A study group of 628 patients aged 70 years and over was identified, and comparisons were made between them and adult patients less than 70 years of age. RESULTS In the elderly group the 30-day mortality was 33 of 628 (5.3%), and the overall hospital mortality was 40 (6.4%). During this time the 30-day mortality for all adult patients less than 70 years old was 49 of 1787 (2.7%; p < 0.003) and the hospital mortality was 59 (3.3%; p < 0.001). The mean length of postoperative hospital stay (days +/- standard error) in all surviving patients aged 70 years and over was 11.6 +/- 0.4 days, compared with 8.5 +/- 0.2 days in patients less than 70 years old (p < 0.001). Over the time of the study the length of stay in patients less than 70 years old declined from 9.6 +/- 0.4 to 7.2 +/- 0.6 days, whereas it stayed the same for elderly patients. The 30-day mortality and length of stay increased with the risk category of the Parsonnet model. The mean hospital charge for patients aged 70 and over was 114% of that for younger patients. CONCLUSIONS Although mortality, length of stay, and hospital charge are increased in patients 70 years of age and over, they are not excessively so. The results support the continued performance of cardiac surgical procedures in select elderly patients.

Definition and classification of Cardio-Renal Syndromes: workgroup statements from the 7th ADQI Consensus Conference

Acute kidney injury in septic shock: clinical outcomes and impact of duration of hypotension prior to initiation of antimicrobial therapy. Brunkhorst FM et al. Acute renal failure in patients with severe sepsis and septic shock a significant independent risk factor for mortality: results from the German Prevalence Study. Van Biesen W et al. Clinical characteristics of patients developing ARF due to sepsis/systemic inflammatory response syndrome: results of a prospective study. et al. Prognostic factors in acute re-nal failure due to sepsis. Results of a prospective multicentre study. Brain natriuretics peptide: a marker of myo-cardial dysfunction and prognosis during severe sepsis. Persistent preload defect in severe sepsis despite fluid loading: a longitudinal echocardiographic study in patients with septic shock. Myocardial necrosis in ICU patients with acute non-cardiac disease: a prospective study. Troponin as a risk factor for mortality in critically ill patients without acute coronary syndromes. Chronic kidney disease associated mortality in diastolic versus systolic heart failure: a propensity matched study. Am J Cardiol 2007; 99: 393–398 72. Hillege HL, van Gilst WH. Accelerated decline and prognostic impact of renal function after myocardial infarction and the benefits of ACE inhibition: the CATS randomized trial.

The combination of propranolol and magnesium does not prevent postoperative atrial fibrillation

BACKGROUND Atrial fibrillation is a common complication of cardiovascular surgery. Beta-blockers have been shown to decrease the incidence of postoperative atrial fibrillation. However, the use of magnesium is more controversial. It was our hypothesis that adjunctive magnesium sulfate would improve the efficacy of beta-blockers alone in the prevention of postoperative atrial fibrillation. METHODS We prospectively randomized 167 coronary artery bypass patients (mean age 61+/-10 years, 115 men) to receive propranolol alone (20 mg four times daily) or propranolol and magnesium (18 g over 24 hours). Magnesium was begun intraoperatively, and propranolol was started on admission to the intensive care unit. RESULTS Using an intention-to-treat analysis, the incidence of postoperative atrial fibrillation was 19.5% in the propranolol-treated patients and 22.4% in propranolol + magnesium-treated patients (p = 0.65). Because combination therapy resulted in an excess of postoperative hypotension, which required withholding doses of propranolol, an on-treatment analysis was also performed. In this analysis, the incidence of atrial fibrillation was still not significantly different (18.5% in propranolol-treated patients and 10.0% in propranolol + magnesium-treated patients, p = 0.20). CONCLUSIONS Adjunctive magnesium sulfate, in combination with propranolol, does not decrease the incidence of postoperative atrial fibrillation.

Epidemiology of acute kidney injury.

Different definitions for acute kidney injury (AKI) once posed an important impediment to research. The RIFLE consensus classification was the first universally accepted definition for AKI, and has facilitated a much better understanding of the epidemiology of this condition. The RIFLE classification was adapted by a broad platform of world societies, the Acute Kidney Injury Network group, as the preferred AKI diagnostic and staging system. RIFLE defines three increasing severity stages of AKI. One- to two-thirds of intensive care unit (ICU) patients develop AKI according to these criteria which is associated with worse outcomes such as increased length of ICU stay, costs, and mortality. Over the last decade the incidence of AKI has increased, probably as a consequence that baseline characteristics of ICU patients have changed. Another factor that may explain this is that more patients are treated in clinical settings that are associated with high risk for development of AKI. In addition, there may be genetically predetermined risk profiles for development of AKI such homozygotes for the low activity form of the COMT gene. Mortality of AKI patients has decreased over the last few decades, especially when underlying severity of illness is considered. An important consequence of this is the increasing number of surviving AKI patients who develop chronic kidney disease and end-stage kidney disease. In the specific setting of cardiac surgery, AKI occurs in 19-45% of patients. Renal replacement therapy is necessary in approximately 2% of this cohort. AKI that occurs within a 7-day period after cardiac surgery is related to perioperative risk factors, such as preexisting chronic kidney disease, acute ischemia, aorta cross-clamping, or use of cardiopulmonary bypass. AKI that occurs after the first week is mostly a consequence of sepsis or heart failure.

ADQI 7: the clinical management of the Cardio-Renal syndromes: work group statements from the 7th ADQI consensus conference

Many patients with heart failure have underlying renal dysfunction, and similarly, patients with kidney failure are prone to cardiac failure. This has led to the concept of cardio-renal syndromes, which can be an acute or chronic cardio-renal syndrome, when cardiac failure causes deterioration in renal function, or acute and/or chronic Reno-Cardiac syndrome, when renal dysfunction leads to cardiac failure. Patients who develop these syndromes have increased risk of hospital admission and mortality. Although there are clinical guidelines for managing both heart failure and chronic kidney disease, there are no agreed guidelines for managing patients with cardio-renal and/or Reno-Cardiac syndromes, as these patients have typically been excluded from clinical trials. We have therefore reviewed the currently available published literature to outline a consensus of current best clinical practice for these patients.