Incidence of acute myocardial infarction in the evolution of dialysis patients

Background: Although the estimated frequency of coronary artery disease (CAD) in patients on dialysis is very high, there is considerable variation in the studies published to date regarding the rate of acute myocardial infarction (AMI) in these patients. Objective: To establish the incidence of AMI and to analyse the characteristics and consequences of this entity on the clinical progression of incident dialysis patients. Methods: We recorded AMI in the patients treated in our dialysis unit between 01/01/1999 and 31/12/07. The variables assessed were: prior diagnosis of diabetes, hypertension, CAD (AMI or lesions observed in coronary angiography), ischaemic cerebrovascular accident, advanced peripheral artery disease (PAD), atrial fibrillation and tobacco use. Biochemical analyses included: urea, creatinine, haematocrit, calcium, phosphorous, iPTH, lipids and albumin. Follow-up lasted until transplant, death, loss to follow-up or study end in Dec. 2010. Results: Of the 576 patients recruited (aged 64.6 +/- 16 years), 24.7% had diabetes, 82.3% were on haemodialysis (17.7% on peritoneal dialysis), and 34 (5.9%) had a previous diagnosis of CAD. In a follow-up lasting a mean of 40.2 +/- 32 months (1931.5 patientyears), 40 patients (6.9%) suffered an AMI. The incidence was 2.13/100 patient-years. The patients without CAD had an incidence of 1.84/100 patient-years and those with a previous diagnosis of CAD had an incidence of 7.53/100 patient-years. In 22.5% of patients, AMI happened in the first 3 months of dialysis, and 37.5% in the 1st year. Of the 40 AMI, 15 were with ST-segment elevation (incidence: 0.79/100 patient-years) and 25 were non ST-segment elevation (incidence: 1.33/100 patient-years). The factors that predicted the occurrence of AMI in dialysis were older age (OR: 1.037; 95% Cl: 1.009-1.067; P=.011), previous CAD (OR: 3.35; 95% Cl: 1.48-7.16; P=.004), and diabetes as a cause of nephropathy (OR: 2.96; 95% Cl: 1.49-5.86; P=.002). In-hospital mortality was 30%, with 72.5% of deaths occurring in the 1st year and 82.5% in the 2nd; 80% of the patients who underwent a coronary angiography had multi-vessel disease. Conclusions: The incidence of AMI in incident dialysis patients is high. In previous coronary disease patients, the incidence is 3-fold higher. Post-infarction mortality is very high and multi-vessel disease is very frequent.