Patient- and procedure-related factors in the pathophysiology of perioperative myocardial infarction/injury.

BACKGROUND: Perioperative myocardial infarction/injury (PMI) is a frequent, often missed and incompletely understood complication of noncardiac surgery. The aim of this study was to evaluate whether patient- or procedure-related factors are more strongly associated to the development of PMI in patients undergoing repeated noncardiac surgery. METHODS: In this prospective observational study, patient- and procedure-related factors were evaluated for contribution to PMI using: 1) logistic regression modelling with PMI as primary endpoint, 2) evaluation of concordance of PMI occurrence in the first and the second noncardiac surgery (surgery 1 and 2). and 3) the correlation of the extent of cardiomyocyte injury quantified by high-sensitivity cardiac troponin T between surgery 1 and 2. The secondary endpoint was all-cause mortality associated with PMI reoccurrence in surgery 2. RESULTS: Among 784 patients undergoing repeated noncardiac surgery (in total 1'923 surgical procedures), 116 patients (14.8%) experienced PMI during surgery 1. Among these, PMI occurred again in surgery 2 in 35/116 (30.2%) patients. However, the vast majority of patients developing PMI during surgery 2 (96/131, 73.3%) had not developed PMI during surgery 1 (phi-coefficient 0.150, p < 0.001). The correlation between the extent of cardiomyocyte injury occurring during surgery 1 and 2 was 0.153. All-cause mortality following a second PMI in surgery 2 was dependent on time since surgery (adjusted hazard ratio 5.6 within 30 days and 2.4 within 360 days). CONCLUSIONS: In high-risk patients, procedural factors are more strongly associated with occurrence of PMI than patient factors, but patient factors are also contributors to the occurrence of PMI.

Association between self-reported functional capacity and major adverse cardiac events in patients at elevated risk undergoing noncardiac surgery: a prospective diagnostic cohort study.

BACKGROUND: Perioperative cardiovascular guidelines endorse functional capacity estimation, based on 'cut-off' daily activities for risk assessment and climbing two flights of stairs to approximate 4 metabolic equivalents. We assessed the association between self-reported functional capacity and postoperative cardiac events. METHODS: Consecutive patients at elevated cardiovascular risk undergoing in-patient noncardiac surgery were included in this predefined secondary analysis. Self-reported ability to walk up two flights of stairs was extracted from electronic charts. The primary endpoint was a composite of cardiac death and cardiac events at 30 days. Secondary endpoints included the same composite at 1 yr, all-cause mortality, and myocardial injury. RESULTS: Among the 4560 patients, mean (standard deviation) age 73 (SD 8 yr) yr, classified as American Society of Anesthesiologists physical status ≥3 in 61% (n=2786/4560), the 30-day and 1-yr incidences of major adverse cardiac events were 5.7% (258/4560) and 11.2% (509/4560), respectively. Functional capacity less than two flights of stairs was associated with the 30-day composite endpoint (adjusted hazard ratio 1.63, 95% confidence interval [CI] 1.23-2.15) and all other endpoints. The addition of functional capacity information to the revised cardiac risk index (RCRI) significantly improved risk classification (functional capacity plus RCRI vs RCRI: net reclassification improvement [NRI]Events 6.2 [95% CI 3.6-9.9], NRINonevents19.2 [95% CI 18.1-20.0]). CONCLUSIONS: In patients at high cardiovascular risk undergoing noncardiac surgery, self-reported functional capacity less than two flights of stairs was independently associated with major adverse cardiac events and all-cause mortality at 30 days and 1 yr. The addition of self-reported functional capacity to surgical and clinical risk improved risk classification. CLINICAL TRIAL REGISTRATION: INCT 02573532.

Adaptive response of the murine collecting duct to alkali loading.

Fine-tuning of salt and acid-base homeostasis is achieved in the renal collecting duct through the action of intercalated and principal cells. Their activity is tightly regulated adapting to changes in systemic acid-base, fluid, or electrolyte status. The relative number of acid or bicarbonate secretory intercalated cells changes in response to acid or alkali loading. Several factors that may induce collecting duct plasticity in response to acid loading have been identified including cell proliferation, Growth Differentiation Factor 15 (Gdf15), hensin (DMBT1), and SDF1 (or CXCL12). Also, the transcription factors Foxi1 and CP2L1, or the Notch2-Jag1 signaling pathway, may play a role. However, little is known about the mechanisms mediating the adaptive response of the collecting duct to alkali loading. Here, we examined in mouse kidney the response of these factors to alkali loading. Mice were left untreated or received NaHCO3 or NaCl over 7 days. Cell proliferation in vivo was monitored by Ki67 labeling or BrdU incorporation and expression of cell markers, and regulatory factors were examined. Foxi1 and GDF15 were upregulated and CP2L1 downregulated during alkali loading. Ki67 staining and BrdU incorporation were frequent in AQP2-positive cells in the NaCl and NaHCO3 groups, but no evidence was found for increased Ki67 or BrdU staining in bicarbonate-secretory cells consistent with a model that AQP2 positive precursor cells may differentiate into intercalated cells. Thus, alkali loading alters the cellular profile of the collecting duct, which may involve cell proliferation and changes in the network of molecules determining the plasticity of the collecting duct.