Conserving evolutionary history does not result in greater diversity over geological time scales.

Alternative prioritization strategies have been proposed to safeguard biodiversity over macroevolutionary time scales. The first prioritizes the most distantly related species-maximizing phylogenetic diversity (PD)-in the hopes of capturing at least some lineages that will successfully diversify into the future. The second prioritizes lineages that are currently speciating, in the hopes that successful lineages will continue to generate species into the future. These contrasting schemes also map onto contrasting predictions about the role of slow diversifiers in the production of biodiversity over palaeontological time scales. We consider the performance of the two schemes across 10 dated species-level palaeo-phylogenetic trees ranging from Foraminifera to dinosaurs. We find that prioritizing PD for conservation generally led to fewer subsequent lineages, while prioritizing diversifiers led to modestly more subsequent diversity, compared with random sets of lineages. Importantly for conservation, the tree shape when decisions are made cannot predict which scheme will be most successful. These patterns are inconsistent with the notion that long-lived lineages are the source of new species. While there may be sound reasons for prioritizing PD for conservation, long-term species production might not be one of them.

Decoupled ecomorphological evolution and diversification in Neogene-Quaternary horses.

Evolutionary theory has long proposed a connection between trait evolution and diversification rates. In this work, we used phylogenetic methods to evaluate the relationship of lineage-specific speciation rates and the mode of evolution of body size and tooth morphology in the Neogene and Quaternary radiation of horses (7 living and 131 extinct species). We show that diversification pulses are a recurrent feature of equid evolution but that these pulses are not correlated with rapid bursts in phenotypic evolution. Instead, rapid cladogenesis seems repeatedly associated with extrinsic factors that relaxed diversity bounds, such as increasing productivity and geographic dispersals into the Old World. This evidence suggests that diversity dynamics in Equinae were controlled mainly by ecological limits under diversity dependence rather than rapid ecomorphological differentiation.

Determinants of a positive exercise test in patients admitted with acute non-infarct chest pain.

BACKGROUND AND OBJECTIVES: Some patients with suspected unstable angina show ischemia at the exercise treadmill test despite having been medically stabilized. The objective of this study was to determine clinical characteristics predicting a positive exercise treadmill test in patients with suspected unstable angina after medical stabilization. METHODS: In 885 hospitalized patients with medically stabilized unstable angina, the relationship between the result of the pre-discharge exercise treadmill test and clinical characteristics was studied. RESULTS: Mean age was 62+/-9 years and 668 (75%) were male. Exercise test was positive (chest pain and/or ST depression > or =1 mm) in 288 patients (33%). Univariate analysis showed the following associated with ischemia at the exercise test: male gender (56% vs. 20%, P<0.001 ), diabetes mellitus (41% vs. 31%, P=0.009), previous unstable angina (41% vs. 24%, P=0.001), previous stable angina (44% vs. 30%, P<0.001), previous coronary artery bypass grafting (43% vs. 31%, P=0.043), peripheral artery disease (45% vs. 31%) and progressive angina (55% vs. 31%, P<0.001). Multivariate analysis showed the following as independent predictors of ischemia: male gender (OR=2.25), diabetes (OR=4.12), previous unstable angina (OR=3.89), previous stable angina (OR=3.74) and progressive angina (OR=4.05). CONCLUSIONS: In patients with suspected unstable angina, after medical stabilization: (1) the exercise treadmill test is positive in one-third of cases; (2) male gender, diabetes, previous angina (unstable and stable) and progressive angina are independent predictors of ischemia.

Predictors of multivessel disease in cases of acute chest pain.

BACKGROUND: Patients with unstable angina not showing ischemia at the exercise treadmill test after medical stabilization usually have a low-risk coronary anatomy. However, some of them have multivessel disease, and it is not known what characteristics are associated with the extension of the coronary artery disease in this subset of patients. OBJECTIVE: To determine clinical and exertional characteristics associated with multivessel disease in patients with unstable angina and a negative exercise test. METHODS: 312 hospitalised patients with unstable angina and a negative exercise test who had undergone cardiac catheterization were reviewed. The relationship between coronariographic findings (presence of multivessel disease) and clinical characteristics, exercise parameters and left ventricular function was studied. RESULTS: Multivessel disease was present in 97 patients (31%). The following variables were associated with the presence of multivessel disease: age more than 65 years old, previous myocardial infarction, previous admissions because of unstable angina, peripheral artery disease, presence of more than two coronary risk factors, left ventricular dysfunction, functional capacity less than 6 METS, duration of exercise less than 8 min and less than 85% of the maximum heart rate. Multivariate analysis showed, as independent predictors of multivessel disease: previous myocardial infarction, previous admissions because of unstable angina, presence of more than two coronary risk factors and peripheral artery disease. CONCLUSIONS: In patients with medically stabilized unstable angina and a negative exercise test, previous myocardial infarction, previous admissions because of unstable angina, presence of more than two coronary risk factors and peripheral artery disease, but not exercise parameters, are independent predictors of multivessel disease.

[Management of unstable angina: advanced age is still an independent predictive factor of more conservative management after prognostic stratification with stress test]. / Manejo de la angina inestable: la edad avanzada continúa siendo un predictor independiente de manejo más conservador tras la estratificación pronóstica mediante prueba de esfuerzo.

BACKGROUND AND OBJECTIVE: In the management of ischemic heart disease, elderly patients constitute a subgroup that, despite having a worse prognosis, are usually managed more conservatively. The objective of this study was to evaluate if, in the management of unstable angina, a more conservative attitude in elderly patients is maintained after stratification by exercise test. PATIENTS AND METHODS: The study population is constitude by 859 patients admitted to hospital due to suspected unstable angina that were referred to exercise test after medical stabilization. The management (invasive versus conservative, according to submission to cardiac catheterization or not) of patients was retrospectively studied, comparing patients < or = 70 versus > 70 years-of age. RESULTS: Out of the 859 patients, 156 (18%) were > 70 years old, and the exercise test was positive in 281 (33%). Cardiac catheterization was performed in 494 (57%): 62% in older and 38% in younger patients (p < 0.0001). Other characteristics associated with a more conservative management were: a negative exercise test, > 85% of the maximum heart rate, duration of exercise test more than 6 minutes, female gender, smoking and absence of episodes of rest angina. In the multivariate analysis, the statistically significant characteristics associated with an invasive management were the result of the exercise test (OR for positive result: 4.50; IC 95% = 2.73-7.63; p < 0.0001), the duration of exercise (OR for > or = 6 minutes: 0.51; IC 95% = 0.29-0.88; p = 0.0177), the percentage of the maximum heart rate (OR for > or = 85%: 0.65; IC 95% = 0.42-0.98; p = 0.0391) and age (OR for > 70 years 0.36; IC 95% = 0.20-0.62; p = 0.0004). CONCLUSIONS: In the management of unstable angina, elderly patients constitute a more conservatively managed subgroup even after risk stratification with exercise test.

Effects of angiotensin converting enzyme inhibitors in hypertensive patients with aortic valve stenosis: a drug withdrawal study.

OBJECTIVE: To determine the effects of angiotensin converting enzyme (ACE) inhibitors in hypertensive patients with aortic valve stenosis (AS). DESIGN: Observational, drug withdrawal, single blinded study, with randomisation of the order of tests. SETTING: Hypertension and asymptomatic AS. PATIENTS AND INTERVENTIONS: 20 patients (aged 73 (9) years, valve area 0.7 (0.3) cm2, left ventricular ejection fraction > or = 45%) were enrolled. Each patient underwent two sets of tests (with and without taking the drug), each of which included clinical evaluation, Doppler echocardiogram, and symptom limited exercise echocardiography. MAIN OUTCOME MEASURES: Functional and haemodynamic variables while taking and not taking ACE inhibitors. RESULTS: Drug intervention induced no change in patients' subjective functional class. While taking ACE inhibitors, patients had a lower systolic blood pressure (140 (18) mm Hg with ACE inhibitors v 159 (12) mm Hg without ACE inhibitors, p = 0.02), a higher mean pressure gradient (34 (15) mm Hg v 28 (18) mm Hg, p = 0.037), and a higher left ventricular stroke work loss (19 (6)% v 14 (10)%, p = 0.009). Other baseline functional and haemodynamic parameters were unmodified. Five patients had an abnormal blood pressure response during one of the exercise tests (two patients while taking the drug and three patients while not taking the drug). When taking ACE inhibitors, patients had a higher stroke volume at peak stress (59 (11) ml v 54 (25) ml, p = 0.046). All other stress variables remained constant. CONCLUSIONS: In AS, the afterload relief caused by ACE inhibitors is blunted by a parallel increase in the pressure gradient. However, ACE inhibitors favourably affect stress haemodynamic function in most hypertensive patients with AS and should not be discontinued.

Evaluation of the specificity of morphological electrocardiographic criteria for the differential diagnosis of wide QRS complex tachycardia in patients with intraventricular conduction defects.

BACKGROUND: Although several ECG criteria have been described for the differential diagnosis of tachycardias with a wide QRS complex, their applicability in patients with preexisting intraventricular conduction defects (IVCDs) has been questioned. The specificity of previously described criteria in this context is unknown. METHODS AND RESULTS: We analyzed prospectively the specificity of the QRS morphological criteria previously described in ECGs during sinus rhythm of 232 patients with IVCD. Only 5 of 12 analyzed criteria had a specificity > or = 0.90 among our patients: (1) a triphasic configuration (Rsr' or Rr') QRS complex in V1 in the presence of a right bundle-branch block morphology (BBBM); (2) a QS, QR, or R QRS pattern in V6 in the presence of a right BBBM; (3) any Q in V6 in the presence of a left BBBM; (4) a concordant pattern in all precordial leads; and (5) the absence of an RS complex in all precordial leads (particularly useful for left BBBM). The following criteria--QRS duration > 140 ms; a left axis with right BBBM, right superior axis with right BBBM, monophasic or biphasic R wave in V1 with right BBBM, and a relation R/S < 1 with right BBBM; an R > 30 ms in lead V1 or V2 with left BBBM, > 60 ms from QRS onset to S nadir with left BBBM, a notched downstroke S wave with left BBBM, and an R-to-S interval > 100 ms in one precordial lead--had a specificity of 0.43, 0.54, 0.87, 0.80, 0.85, 0.78, 0.66, 0.69, and 0.63 (0.84 in right BBBM), respectively. CONCLUSIONS: Most of the previously described morphological criteria favoring ventricular tachycardia are present in a substantial percentage of patients with IVCD during sinus rhythm. These findings suggest a limited applicability of these criteria in this subset of patients.