Prognostic Value of Renal Function in STEMI With PCI
Prognostic Value of Renal Function in STEMI With PCI
This prospective, observational, single-centre study was conducted at the Institute of Cardiology in Warsaw (Anin). All consecutive patients with STEMI (diagnosed according to European Society for Cardiology [ESC]/American College of Cardiology [ACC] guidelines current at the time) treated with pPCI between February 2001 and October 2002 were included in a prospective registry (ANIN Myocardial Infarction Registry). There were no exclusion criteria; in particular, patients with cardiogenic shock, pulmonary oedema, known renal failure or advanced age were not excluded.
The study complies with the Declaration of Helsinki and the ethics committee approved its research protocol.
The Institute of Cardiology in Warsaw is a tertiary cardiology centre performing about 4,000 coronary angiographies and 2,500 PCIs, including about 700 pPCI for STEMI, per year, where round-the-clock interventional duty for acute coronary syndrome patients was started in February 2001.
The majority of patients were transferred to our centre from non-PCI hospitals. Informed consent for interventional procedures was obtained in the emergency department, and patients were transported directly to the cath lab (not via the cardiac care unit [CCU]). The aim was to reduce door-to-balloon time. Blood samples for baseline serum creatinine were drawn from the arterial sheath prior to contrast administration. The operator was unaware of the lab results while performing the procedure.
Primary angioplasty was performed in all patients in accordance with generally accepted standards. At the time of this study, the pre-procedure protocol included a loading dose (300–500 mg orally) of acetylsalicylic acid. Unfractionated heparin (bolus intravenous injection of 100 IU per kg body weight or 70 IU if prophylactic abciximab was planned) and a loading dose of clopidogrel (at that time 300 mg orally) were usually given at the start of the procedure. Prophylactic abciximab use was left to the discretion of the operator. Reperfusion success was defined as a Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow.
Baseline demographic, clinical, laboratory and angiographic data were collected on admission and angiographic data on completion of the pPCI using pre-printed forms. Data regarding in-hospital course (death, major bleeding, stroke, re-infarction) were obtained from patients' charts. Major adverse cardiac and cerebrovascular events (MACCEs) were defined according to the approved criteria (in particular, major bleeding as in TIMI bleeding score, and re-infarction as in the GUSTO-I trial). Vital status at 30 days was established by telephone calls to patients or their cardiologists. Missing data were obtained from the National Census Registry. A dedicated computerised database was set up and regularly updated.
Renal function was assessed by estimation of glomerular filtration rate (eGFR) using abbreviated Modification of Diet in Renal Disease formula, as recommended by the National Kidney Foundation: eGFR = 32,788 × (serum creatinine) × age × (1.210 if black) × (0.742 if female).
Patients were staged according to Kidney Disease Outcomes Quality Initiative (K-DOQI) guidelines. CKD was defined as eGFR below 60 ml/min/1.73 m with or without evidence of kidney damage. The clinical laboratory at our institution reported creatinine values greater than 133 μmol/L as abnormal for either gender.
Typical statistical methods were used. Continuous data were expressed as means ± standard deviation (SD) and categorical data as numeric values and percentages. Additionally, age was expressed as a range. Comparison of continuous variables was performed by means of student t-test. Chi square test or Fisher exact test was used for comparison of categorical variables, as appropriate. Time-to-event data were summarised as Kaplan–Meier estimates and compared with log-rank test.
To adjust for baseline differences between study groups, all variables associated with the clinical end points at univariate analysis (p<0.1 for selection) were tested in multi-variate analyses; Cox proportional hazards model and logistic regression were used to identify independent predictors of mortality and final TIMI grade 3 flow, respectively (tested variables were sex, age, history of hypertension, diabetes mellitus, smoking status, prior MI or PCI, heart rate [HR] and systolic blood pressure [SBP] on admission, eGFR, Killip class, localisation of MI, abciximab usage, multi-vessel disease [MVD], initial TIMI grade flow and final TIMI grade flow exclusively for mortality). Final models were built by forward stepwise variable selection, with a p value <0.05 used as a criterion for entry and p >0.1 for removal of variables. Results were presented as hazard ratios (HRs) with 95% confidence intervals (CIs).
All reported p values are two-tailed, and a p value <0.05 was considered statistically significant unless otherwise specified. All statistical analyses were carried out using the Statistical Package for Social Sciences version 15.0 (SPSS Inc., Chicago, IL, USA).
Methods
Study Design and Patient Population
This prospective, observational, single-centre study was conducted at the Institute of Cardiology in Warsaw (Anin). All consecutive patients with STEMI (diagnosed according to European Society for Cardiology [ESC]/American College of Cardiology [ACC] guidelines current at the time) treated with pPCI between February 2001 and October 2002 were included in a prospective registry (ANIN Myocardial Infarction Registry). There were no exclusion criteria; in particular, patients with cardiogenic shock, pulmonary oedema, known renal failure or advanced age were not excluded.
The study complies with the Declaration of Helsinki and the ethics committee approved its research protocol.
Clinical Setting
The Institute of Cardiology in Warsaw is a tertiary cardiology centre performing about 4,000 coronary angiographies and 2,500 PCIs, including about 700 pPCI for STEMI, per year, where round-the-clock interventional duty for acute coronary syndrome patients was started in February 2001.
The majority of patients were transferred to our centre from non-PCI hospitals. Informed consent for interventional procedures was obtained in the emergency department, and patients were transported directly to the cath lab (not via the cardiac care unit [CCU]). The aim was to reduce door-to-balloon time. Blood samples for baseline serum creatinine were drawn from the arterial sheath prior to contrast administration. The operator was unaware of the lab results while performing the procedure.
Primary angioplasty was performed in all patients in accordance with generally accepted standards. At the time of this study, the pre-procedure protocol included a loading dose (300–500 mg orally) of acetylsalicylic acid. Unfractionated heparin (bolus intravenous injection of 100 IU per kg body weight or 70 IU if prophylactic abciximab was planned) and a loading dose of clopidogrel (at that time 300 mg orally) were usually given at the start of the procedure. Prophylactic abciximab use was left to the discretion of the operator. Reperfusion success was defined as a Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow.
Data Collection
Baseline demographic, clinical, laboratory and angiographic data were collected on admission and angiographic data on completion of the pPCI using pre-printed forms. Data regarding in-hospital course (death, major bleeding, stroke, re-infarction) were obtained from patients' charts. Major adverse cardiac and cerebrovascular events (MACCEs) were defined according to the approved criteria (in particular, major bleeding as in TIMI bleeding score, and re-infarction as in the GUSTO-I trial). Vital status at 30 days was established by telephone calls to patients or their cardiologists. Missing data were obtained from the National Census Registry. A dedicated computerised database was set up and regularly updated.
Estimation of Renal Function
Renal function was assessed by estimation of glomerular filtration rate (eGFR) using abbreviated Modification of Diet in Renal Disease formula, as recommended by the National Kidney Foundation: eGFR = 32,788 × (serum creatinine) × age × (1.210 if black) × (0.742 if female).
Patients were staged according to Kidney Disease Outcomes Quality Initiative (K-DOQI) guidelines. CKD was defined as eGFR below 60 ml/min/1.73 m with or without evidence of kidney damage. The clinical laboratory at our institution reported creatinine values greater than 133 μmol/L as abnormal for either gender.
Statistics
Typical statistical methods were used. Continuous data were expressed as means ± standard deviation (SD) and categorical data as numeric values and percentages. Additionally, age was expressed as a range. Comparison of continuous variables was performed by means of student t-test. Chi square test or Fisher exact test was used for comparison of categorical variables, as appropriate. Time-to-event data were summarised as Kaplan–Meier estimates and compared with log-rank test.
To adjust for baseline differences between study groups, all variables associated with the clinical end points at univariate analysis (p<0.1 for selection) were tested in multi-variate analyses; Cox proportional hazards model and logistic regression were used to identify independent predictors of mortality and final TIMI grade 3 flow, respectively (tested variables were sex, age, history of hypertension, diabetes mellitus, smoking status, prior MI or PCI, heart rate [HR] and systolic blood pressure [SBP] on admission, eGFR, Killip class, localisation of MI, abciximab usage, multi-vessel disease [MVD], initial TIMI grade flow and final TIMI grade flow exclusively for mortality). Final models were built by forward stepwise variable selection, with a p value <0.05 used as a criterion for entry and p >0.1 for removal of variables. Results were presented as hazard ratios (HRs) with 95% confidence intervals (CIs).
All reported p values are two-tailed, and a p value <0.05 was considered statistically significant unless otherwise specified. All statistical analyses were carried out using the Statistical Package for Social Sciences version 15.0 (SPSS Inc., Chicago, IL, USA).