Intradialytic Hypotension and Cardiac Arrhythmias in Patients Undergoing Maintenance Hemodialysis : Results from the Monitoring in Dialysis Study

The incidence of acute coronary-artery occlusion among patients with sudden cardiac arrest outside of the hospital is unknown, and the role of reperfusion therapy has not been determined. We therefore performed immediate coronary angiography and angioplasty when indicated in survivors of out-of-hospital cardiac arrest. Between September 1994 and August 1996, coronary angiography was performed in 84 consecutive patients between the ages of 30 and 75 years who had no obvious noncardiac cause of cardiac arrest. Sixty of the 84 patients had clinically significant coronary disease on angiography, 40 of whom had coronary-artery occlusion (48 percent). Angioplasty was attempted in 37 patients and was technically successful in 28. Clinical and electrocardiographic findings, such as the occurrence of chest pain and the presence of ST-segment elevation, were poor predictors of acute coronary-artery occlusion. The in-hospital survival rate was 38 percent. Multivariate logistic-regression analysis revealed that successful angioplasty was an independent predictor of survival (odds ratio, 5.2; 95 percent confidence interval, 1.1 to 24.5; P=0.04). Acute coronary-artery occlusion is frequent in survivors of out-of-hospital cardiac arrest and is predicted poorly by clinical and electrocardiographic findings. Accurate diagnosis by immediate coronary angiography can be followed in suitable candidates by coronary angioplasty, which seems to improve survival.

Intradialytic hypotension is a serious and frequent complication of hemodialysis; however, there is no evidence-based consensus definition of intradialytic hypotension. As a result, coherent evaluation of the effects of intradialytic hypotension is difficult. We analyzed data from 1409 patients in the HEMO Study and 10,392 patients from a single large dialysis organization to investigate the associations of commonly used intradialytic hypotension definitions and mortality. Intradialytic hypotension definitions were selected a priori on the basis of literature review. For each definition, patients were characterized as having intradialytic hypotension if they met the corresponding definition in at least 30% of baseline exposure period treatments or characterized as control otherwise. Overall and within subgroups of patients with predialysis systolic BP<120 or 120-159 mmHg, an absolute nadir systolic BP<90 mmHg was most potently associated with mortality. Within the subgroup of patients with predialysis BP≥160 mmHg, nadir BP<100 mmHg was most potently associated with mortality. Intradialytic hypotension definitions that considered symptoms, interventions, and decreases in BP during dialysis were not associated with outcome, and when added to nadir BP, symptom and intervention criteria did not accentuate associations with mortality. Our results suggest that nadir-based definitions best capture the association between intradialytic hypotension and mortality.

Patients with end-stage renal disease requiring dialysis have limited tolerance of metabolic and volume-related deviations from normal ranges; in addition, the prevalence of cardiovascular disease is high among such patients. Given these problems, we hypothesized that a long interdialytic interval is associated with adverse events in patients receiving hemodialysis. We studied 32,065 participants in the End-Stage Renal Disease Clinical Performance Measures Project, a nationally representative sample of U.S. patients receiving hemodialysis three times weekly, at the end of calendar years 2004 through 2007. We compared rates of death and cardiovascular-related hospital admissions on the day after the long (2-day) interdialytic interval with rates on other days. The mean age of the cohort was 62.2 years; 24.2% of the patients had been receiving dialysis treatment for 1 year or less. Over a mean follow-up interval of 2.2 years, the following event rates were higher on the day after the long interval than on other days: all-cause mortality (22.1 vs. 18.0 deaths per 100 person-years, P<0.001), mortality from cardiac causes (10.2 vs. 7.5, P<0.001), infection-related mortality (2.5 vs. 2.1, P = 0.007), mortality from cardiac arrest (1.3 vs. 1.0, P = 0.004), mortality from myocardial infarction (6.3 vs. 4.4, P<0.001), and admissions for myocardial infarction (6.3 vs. 3.9, P<0.001), congestive heart failure (29.9 vs. 16.9, P<0.001), stroke (4.7 vs. 3.1, P<0.001), dysrhythmia (20.9 vs. 11.0, P<0.001), and any cardiovascular event (44.2 vs. 19.7, P<0.001). The long (2-day) interdialytic interval is a time of heightened risk among patients receiving hemodialysis. (Funded by the National Institutes of Health.).