Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

[EX Q]: Context: Pulmonary vein (PV) isolation is a curative treatment for patients with atrial fibrillation. The aim of this study was to evaluate prospectively the effects of adenosine administration on the PV activity and atrio-venous conduction after PV isolation.', 'Twenty-nine patients (21 m; age: 55+/-8 years) were submitted to ostial PV isolation guided by basket catheter recordings. After successful isolation, the effects of a 12 mg intravenous bolus of adenosine were tested in 62 PVs. In 22/62 PVs (35%), left atrium (LA)-to-PV conduction was transiently (16.6+/-7.1 s, range: 3.8-27.9 s) or permanently (3 PVs) restored in response to adenosine administration. The prevalence of this phenomenon was 39% in left superior PVs, 43% in right superior PVs, and 22% in left inferior PVs (p=0.365). It occurred more frequently in the presence of dissociated PV activity (11/15 PVs, 73% vs. 11/47 PVs, 23%; p=0.002), whereas it was not influenced by the median duration of the radiofrequency current (RFC) delivery for each PV [19 (IQR: 12-26) min vs. 16 (IQR: 11-24) min: p=0.636]. A lengthening or shortening of the LA-PV conduction time was observed at LA-PV conduction appearance and disappearance in 36% and 55% of the cases, respectively. Further RFC applications (median: 5.5 min, IQR: 4-11 min) at the residual conduction breakthrough(s) indicated by the basket catheter recordings definitively eliminated adenosine-induced recovery of LA-PV conduction in all cases. Finally, when present, intrinsic PV discharge was invariably depressed by adenosine administration.
Answer: Adenosine may transiently or permanently re-establish LA-PV conduction after apparently successful PV isolation. This phenomenon is abolished by additional RFC delivery. However, its possible influence on the clinical results of PV ablation must be evaluated by properly designed, randomized studies.
[EX A]: Does adenosine restore atrio-venous conduction after apparently successful ostial isolation of the pulmonary veins?

[EX Q]: Context: Cardiac overexpression of the β-adrenoreceptor (βAR)-coupled stimulatory G-protein subunit Gαs enhances inotropic responses to adrenergic stimulation and improves survival in mice under βAR blockade. The authors recently identified three common haplotypes in the GNAS gene encoding Gαs, with the greatest Gαs protein expression and signal transduction in haplotype *3 carriers and less in haplotype *2 and *1 carriers. The authors tested the hypothesis that these GNAS variants result in altered mortality in patients after coronary artery bypass graft surgery, particularly in those receiving βAR blockade.', 'This prospective analysis included 1,627 European ancestry patients undergoing primary coronary artery bypass graft surgery. Patients were genotyped for two GNAS haplotype tagging single-nucleotide polymorphisms defining three major haplotypes. Up to 5-yr all-cause mortality was estimated using a Cox proportional hazard model; hazard ratios and 95% CIs were calculated while adjusting for demographics, clinical covariates, and the new EuroSCORE II.', 'Univariate analysis revealed haplotype-dependent 5-yr mortality rates (*1/*1: 18.9%, *2/*1: 13.7%, *2/*2: 9.3%, *3/*1: 10.6%, *3/*2: 9.1%, and *3/*3: 9.6%; P = 0.0006). After adjustment for other predictors of death, homozygote haplotype *1 carriers showed a doubled risk for death (hazard ratio, 2.2; 95% CI, 1.2 to 3.8; P = 0.006). Considering only patients receiving βAR blockers (n = 1,267), the adjusted risk of death even tripled (hazard ratio, 3.0; 95% CI, 1.5 to 6.1; P = 0.002).
Answer: GNAS haplotypes independently associate with an increased risk of death after primary coronary artery bypass graft surgery. These results are most pronounced in patients receiving βAR blockers, strengthening the rationale for personalized treatment, to decrease medication side effects and improve outcomes.
[EX A]: Do gNAS gene variants affect β-blocker-related survival after coronary artery bypass grafting?

[EX Q]: Context: Emphysema, especially in the upper lobes, is frequently observed in association with idiopathic pulmonary fibrosis (IPF). However, the combination of emphysema plus IPF has received little attention.', 'To investigate the additional functional impairment from emphysema in IPF patients.', 'Twenty-one patients (mean age 66 y, 20 men) (Group I) who had both IPF (mean 35% of total lung volume) and emphysema (mean 14% of total lung volume) were compared to a group of 21 subjects who had IPF but no emphysema (Group II). The groups were matched for (among other criteria) the total extent of disease. Pulmonary function tests, Medical Research Council dyspnea score, 6-min walk test, and radiographic extents of both IPF and emphysema were obtained for each patient. The Composite Physiologic Index was calculated. In the total population (n = 42), the independent contributions of IPF and emphysema to several physiologic variables were investigated by using stepwise multiple regression analysis.', 'Despite the limited extent of emphysema, Groups I and II had similar physiologic impairment. Only residual volume and total lung capacity were significantly higher in Group I. According to stepwise multiple regression analysis, the extent of IPF and either the presence or the extent of emphysema in the total population were independent and significant predictors of dyspnea score, 6-min walk test, P(aO2), forced expiratory volume in the first second (FEV(1)), forced vital capacity (FVC), FEV1/FVC, the diffusing capacity of the lung for carbon monoxide, carbon monoxide diffusing capacity adjusted for alveolar volume (gas-transfer coefficient), and residual volume. The Composite Physiologic Index was closely related to the extent of IPF (r = 0.65, p < 0.0001) and to the dyspnea score (rho = 0.59, p < 0.0001).
Answer: In former smokers with IPF, the presence and the extent of emphysema have a profound influence on physiologic function in terms of both further impairment and confounding effects.
[EX A]:
Does the presence of emphysema further impair physiologic function in patients with idiopathic pulmonary fibrosis?