目录
2018年第2期(发布时间: May 22, 2018 发布者:张燕舞)  下载: 2018年第2期.doc       全选  导出
1   2018-05-22 09:56:12.627 心房颤动患者的地高辛水平和死亡率 (点击量:0)

地高辛在心房颤动(AF)房率控制中的作用多年来基于对死亡率增加的担忧而受到质疑。 ARISTOTLE试验(比较大约18,000例房颤患者的抗凝治疗)的一项表现良好的事后亚组分析显示,地高辛的使用与≥1.2ng / mL水平的死亡风险显着相关。 我们几乎从不使用地高辛作为第一个控制率的药物,很少将其添加到其他控制率的药物中。

BACKGROUND Digoxin is widely used in patients with atrial fibrillation (AF).

OBJECTIVES The goal of this paper was to explore whether digoxin use was independently associated with increased mortality in patients with AF and if the association was modified by heart failure and/or serum digoxin concentration.

METHODS The association between digoxin use and mortality was assessed in 17,897 patients by using a propensity score-adjusted analysis and in new digoxin users during the trial versus propensity score-matched control participants. The authors investigated the independent association between serum digoxin concentration and mortality after multivariable adjustment.

RESULTS At baseline, 5,824 (32.5%) patients were receiving digoxin. Baseline digoxin use was not associated with an increased risk of death (adjusted hazard ratio [HR]: 1.09; 95% confidence interval [CI]: 0.96 to 1.23; p = 0.19). However, patients with a serum digoxin concentration ≥1.2 ng/ml had a 56% increased hazard of mortality (adjusted HR: 1.56; 95% CI: 1.20 to 2.04) compared with those not on digoxin. When analyzed as a continuous variable, serum digoxin concentration was associated with a 19% higher adjusted hazard of death for each 0.5-ng/ml increase (p = 0.0010); these results were similar for patients with and without heart failure. Compared with propensity score-matched control participants, the risk of death (adjusted HR: 1.78; 95% CI: 1.37 to 2.31) and sudden death (adjusted HR: 2.14; 95% CI: 1.11 to 4.12) was significantly higher in new digoxin users.

CONCLUSIONS In patients with AF taking digoxin, the risk of death was independently related to serum digoxin concentration and was highest in patients with concentrations ≥1.2 ng/ml. Initiating digoxin was independently associated with higher mortality in patients with AF, regardless of heart failure.

2   2018-05-22 09:50:23.827 用于评估可疑急性主动脉综合征的诊断工具 (点击量:0)

在评估怀疑患有急性主动脉综合征(AAS)的患者时,误诊和过度怀疑是个问题。该项前瞻性多中心主动脉夹层检测风险评分(ADD-RS)加D二聚体在疑似急性主动脉夹层(ADvISED)研究中使用ADD-RS和D-二聚体的组合作为超过1800名此类患者的诊断工具。 ADD-RS≤1加负向D-二聚体的组合有效地排除了AAS,在约300名患者中仅缺少一个病例,并且将使大约60%的具有低AAS概率的患者免于不必要的结局性血管成像。 虽然这种初步的经验似乎很有希望,但在推荐将这种组合作为诊断工具的常规使用之前,需要在更广泛的患者群体中进行额外的验证。

BACKGROUND Acute aortic syndromes (AASs) are rare and severe cardiovascular emergencies with unspecific symptoms. For AASs, both misdiagnosis and overtesting are key concerns, and standardized diagnostic strategies may help physicians to balance these risks. D-dimer (DD) is highly sensitive for AAS but is inadequate as a stand-alone test. Integration of pretest probability assessment with DD testing is feasible, but the safety and efficiency of such a diagnostic strategy are currently unknown.

METHODS In a multicenter prospective observational study involving 6 hospitals in 4 countries from 2014 to 2016, consecutive outpatients were eligible if they had≥1 of the following: chest/abdominal/back pain, syncope, perfusion deficit, and if AAS was in the differential diagnosis. The tool for pretest probability assessment was the aortic dissection detection risk score (ADD-RS, 0-3) per current guidelines. DD was considered negative (DD-) if<500 ng/mL. Final case adjudication was based on conclusive diagnostic imaging, autopsy, surgery, or 14-day follow-up. Outcomes were the failure rate and efficiency of a diagnostic strategy for ruling out AAS in patients with ADD-RS=0/DD- or ADD-RS≤1/DD-.

RESULTS A total of 1850 patients were analyzed. Of these, 438 patients (24%) had ADD-RS=0, 1071 patients (58%) had ADD-RS=1, and 341 patients (18%) had ADD-RS>1. Two hundred forty-one patients (13%) had AAS: 125 had type A aortic dissection, 53 had type B aortic dissection, 35 had intramural aortic hematoma, 18 had aortic rupture, and 10 had penetrating aortic ulcer. A positive DD test result had an overall sensitivity of 96.7% (95% confidence interval [CI], 93.6-98.6) and a specificity of 64% (95% CI, 61.6-66.4) for the diagnosis of AAS; 8 patients with AAS had DD-. In 294 patients with ADD-RS=0/DD-, 1 case of AAS was observed. This yielded a failure rate of 0.3% (95% CI, 0.1-1.9) and an efficiency of 15.9% (95% CI, 14.3-17.6) for the ADD-RS=0/DD- strategy. In 924 patients with ADD-RS≤1/DD-, 3 cases of AAS were observed. This yielded a failure rate of 0.3% (95% CI, 0.1-1) and an efficiency of 49.9% (95% CI, 47.7-52.2) for the ADD-RS≤1/DD- strategy.

CONCLUSIONS Integration of ADD-RS (either ADD-RS=0 or ADD-RS≤1) with DD may be considered to standardize diagnostic rule out of AAS.

CLINICAL TRIAL REGISTRATION URL: https://www.clinicaltrials.gov. Unique identifier: NCT02086136.

3   2018-04-24 10:23:58.727 胆固醇变异性与冠状动脉粥样硬化进展和临床结局相关 (点击量:0)

目标:利用系列血管内超声检查(IVUS),检查个体内血脂变异性、冠状动脉粥样硬化进展和临床结局的之间的关联。

方法和结果:我们对9项临床试验共4976例冠状动脉疾病患者进行了事后病人级分析,这些患者在多种医学治疗中接受了一系列的冠状动脉IVUS。我们评估了粥样斑块体积百分比(ΔPAV)的进展、临床结局和脂质变异性(包括低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)、非 HDL-C、总胆固醇(TC)/ HDL-C和载脂蛋白B(ApoB))。使用个体内在3个月、6个月、12个月、18个月和24个月标准差测量血脂参数的变异性。导致动脉粥样硬化脂蛋白变异性与ΔPAV显着相关(LDL-C:比值比(OR)为1.09,95%置信区间(CI)为1.02,1.17,P = 0.01;非HDL-C:OR为1.10,95% CI为1.02,1.18,P = 0.01;TC / HDL-C:OR为1.14,95% CI为1.06,1.24,P = 0.001;ApoB:OR为1.13,95% CI为1.03,1.24,P = 0.01)。生存曲线显示累积的主要不良心血管事件与24个月随访后动脉粥样硬化脂蛋白变异性增加的四分位数之间显着的逐步关系(所有脂蛋白除HDL-C以外的log-rank P <0.01)。在达到的脂蛋白水平和ΔPAV之间注意到更强的相关性(LDL-C:OR为1.27,95% CI为1.17,1.39,P <0.001;非HDL-C:OR为1.32,95% CI为1.21,1.45,P <0.001;TC / HDL-C:OR为1.31,95% CI为1.19,1.45,P <0.001; ApoB:OR为1.20,95% CI为1.07,1.35,P = 0.003)。

结论:尽管导致动脉粥样硬化脂蛋白与动脉粥样硬化进展之间的关联性似乎更强,但导致动脉粥样硬化脂蛋白水平的变异性与冠状动脉粥样硬化进展和临床结局显著相关。这些数据显示实现低度和持续性致动脉粥样硬化脂蛋白的水平在促进斑块消退和改善临床结局中的重要性。

4   2018-04-24 09:54:26.423 冠状动脉钙化与动脉粥样硬化性心血管疾病(ASCVD)事件的10年关联分析:多种族动脉粥样硬化研究(MESA) (点击量:0)

目标:虽然冠状动脉钙化(CAC)已被广泛验证用于预测临床事件,但CAC的大多数结局研究仅评估了冠心病(CHD)而不是动脉粥样硬化性心血管疾病(ASCVD)事件(包括中风)。此外,几乎所有的CAC研究都是短期或中期随访,因此在临床广泛使用之前,需要对具有长期随访的多种族群进行研究。我们试图评估CAC使用基于人群的MESA队列对ASCVD事件10年以上随访的作用,以及CAC与事件的关联是否因性别、种族/民族或年龄类别而异。

方法和结果:我们利用MESA进行了一项共6814名参与者的前瞻性多种族队列研究,其中51%为女性,年龄为45-84岁,在基线时无临床CVD。我们根据年龄、种族/民族,性??别、教育程度、收入、吸烟状况、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇、糖尿病、降脂药物、收缩压、抗高血压药物、有意体育锻炼和体重指数等因素调整后,使用Cox回归模型评估CAC与事件ASCVD之间的关系。分析中仅使用每个个体的第一事件。总体而言,在总研究人群中观察到在中位数为11.1年中有500例ASCVD事件(7.4%)。严重ASCVD包括217例心肌梗塞、188例卒中(非短暂性脑缺血发作)、13例复苏心脏骤停和82例CHD死亡。 在那些CAC = 0的Agatston评分单元的人群中的事件发生率在1.3%至5.6%之间,而CAC> 300的患者中,不同年龄、性别和种族亚群的10年事件发生率在13.1%至25.6%之间。在10年的随访中,所有CAC> 100的参与者不考虑人口特征亚组估计有> 7.5%的风险。不论年龄、性别或种族/民族,各类CAC的十年ASCVD事件发生率稳步增加。保持所有其他风险因素不变时,对于CAC每增加一倍,我们估计ASCVD风险相对增加14%。年龄、性别、种族/种族或基线降脂使用没有显着改变这种关联。

结论:冠状动脉钙化与10年ASCVD风险强烈相关且呈分级形式,因为它与CHD相关,其独立于标准危险因素,并且年龄、性别和种族也类似。虽然CAC = 0的患者10年事件发生率几乎全部低于5%,但CAC≥100的患者一直高于7.5%,这为为预防性治疗提供了潜在的宝贵切入点。冠状动脉钙化强有力地预测了风险,这在所有种族、年龄组和性别中都具有相同的效应,这使其成为预测ASCVD风险的最有用标记。

5   2018-04-24 09:26:46.44 无阻塞性冠状动脉疾病的心绞痛患者的长期临床结局的决定因素:系统评价和Meta分析 (点击量:0)

目标:无梗阻性冠状动脉疾病(CAD)患者的心绞痛的长期预后尚不确定。本分析主要评估此类患者长期不良结局的发生率。

方法和结果:我们检索PubMed、Cochrane图书馆、Embase数据库和临床试验注册数据库,收集以2017年1月以前用英文出版的研究,使用随机效应模型评估全因死亡和非致死性心肌梗死的复合主要结局,以估计汇总发生率。我们确定了54项研究,其中报告了共35039例患有心绞痛并且无梗阻性CAD的患者(平均年龄56岁,男女比例为0.51,97970人年)的结局。随访中位数为5年(四分位数间距3-7年)后,主要终点的汇总发生率为0.98 / 100人年[95%置信区间(CI)0.77-1.19%],其中研究间存在显著的异质性(I2 = 91%,P <0.001)。主要结局中相关的有普遍的血脂异常(P = 0.016)、糖尿病(P = 0.035)和高血压(P = 0.016)。纳入低阻塞性CAD患者的研究显示,主要终点(1.32 / 100人年,95%CI 1.02-1.62)的发生率比仅包括“完全正常”冠状动脉患者(0.52 / 100人年,95%CI分别为0.34-0.79; P <0.01)的更高。主要结局的发生率在仅招收记录有心肌缺血的患者和不管缺血是否存在的患者的研究之间没有显著差异。然而,通过非侵入性成像技术记录缺血的研究其发生率较高(P = 0.02)。总的来说,这些患者的复发性住院率很高。

结论:无梗阻性CAD的心绞痛有不同的预后。主要不良事件的主要决定因素是存在“一些”冠状动脉粥样硬化、与更差的临床结局相关的明确的心肌缺血。病人的“生活质量”也因住院率高、心绞痛复发以及反复冠状动脉造影等有所恶化。

6   2018-05-22 10:10:33.75 先前无症状心肌梗死对急性心肌梗死患者预后的意义 (点击量:0)

为了调查首次急性心肌梗死(AMI)患者中无症状心肌梗塞(MI)的患病率,以及其与长期随访中死亡率和主要不良心血管事件(MACE)的关系。在近400例心肌梗塞(MI)患者中,进行了晚期钆增强(LGE)的心脏磁共振成像(CMR),并且超过8%的人群显示先前无症状的MI。 这些患者的死亡率和主要不良心脏事件风险随后增加3-4倍。 因此,在患有临床MI的患者中,通过CMR与LGE鉴定沉默MI具有重要的预后意义,并且应该对这些患者进行积极的管理。

OBJECTIVES:This study investigated the prevalence of silent myocardial infarction (MI) in patients presenting with first acute myocardial infarction (AMI), and its relation with mortality and major adverse cardiovascular events (MACE) at long-term follow-up.

BACKGROUND:Up to 54% of MI occurs without apparent symptoms. The prevalence and long-term prognostic implications of previous silent MI in patients presenting with seemingly first AMI are unclear.

METHODS:A 2-center observational longitudinal study was performed in 392 patients presenting with first AMI between 2003 and 2013, who underwent late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) examination within 14 days post-AMI. Silent MI was assessed on LGE-CMR images by identifying regions of hyperenhancement with an ischemic distribution pattern in other territories than the AMI. Mortality and MACE (all-cause death, reinfarction, coronary artery bypass grafting, and ischemic stroke) were assessed at 6.8 ± 2.9 years follow-up.

RESULTS:Thirty-two patients (8.2%) showed silent MI on LGE-CMR. Compared with patients without silent MI, mortality risk was higher in patients with silent MI (hazard ratio: 3.87; 95% confidence interval: 1.21 to 12.38; p = 0.023), as was risk of MACE (hazard ratio: 3.10; 95% confidence interval: 1.22 to 7.86; p = 0.017), both independent from clinical and infarction-related characteristics.

CONCLUSIONS:Silent MI occurred in 8.2% of patients presenting with first AMI and was independently related to poorer long-term clinical outcome, with a more than 3-fold risk of mortality and MACE. Silent MI holds prognostic value over important traditional prognosticators in the setting of AMI, indicating that these patients represent a high-risk subgroup warranting clinical awareness.

7   2018-05-22 10:04:51.19 运动员心脏猝死风险 (点击量:0)

虽然心脏性猝死(SCD)是运动员死亡的主要医疗原因,但其确切发病率仍不清楚。 到目前为止,最好的估计已经表明,在50,000个运动员年中约有1个发生。 在一项使用加拿大数据库2009年至2014年的数据记录的一项新研究中,该数据库记录了加拿大安大略省所有医院外突发心脏骤停(SCA),运动员SCA的总体速率为每10万运动员年为0.76。 44%的患者在SCA后仍然出院,SCD总发生率为每100,000运动员年0.42。 这些数据表明,运动员SCD的发生率是以前估计的四分之一,并提出了关于预参加筛查的作用的问题。

BACKGROUND The incidence of sudden cardiac arrest during participation in sports activities remains unknown. Preparticipation screening programs aimed at preventing sudden cardiac arrest during sports activities are thought to be able to identify at-risk athletes; however, the efficacy of these programs remains controversial. We sought to identify all sudden cardiac arrests that occurred during participation in sports activities within a specific region of Canada and to determine their causes.

METHODS In this retrospective study, we used the Rescu Epistry cardiac arrest database (which contains records of every cardiac arrest attended by paramedics in the network region) to identify all out-of-hospital cardiac arrests that occurred from 2009 through 2014 in persons 12 to 45 years of age during participation in a sport. Cases were adjudicated as sudden cardiac arrest (i.e., having a cardiac cause) or as an event resulting from a noncardiac cause, on the basis of records from multiple sources, including ambulance call reports, autopsy reports, in-hospital data, and records of direct interviews with patients or family members.

RESULTS Over the course of 18.5 million person-years of observation, 74 sudden cardiac arrests occurred during participation in a sport; of these, 16 occurred during competitive sports and 58 occurred during noncompetitive sports. The incidence of sudden cardiac arrest during competitive sports was 0.76 cases per 100,000 athlete-years, with 43.8% of the athletes surviving until they were discharged from the hospital. Among the competitive athletes, two deaths were attributed to hypertrophic cardiomyopathy and none to arrhythmogenic right ventricular cardiomyopathy. Three cases of sudden cardiac arrest that occurred during participation in competitive sports were determined to have been potentially identifiable if the athletes had undergone preparticipation screening.

CONCLUSIONS In our study involving persons who had out-of-hospital cardiac arrest, the incidence of sudden cardiac arrest during participation in competitive sports was 0.76 cases per 100,000 athlete-years. The occurrence of sudden cardiac arrest due to structural heart disease was uncommon during participation in competitive sports. (Funded by the National Heart, Lung, and Blood Institute and others.).

8   2018-05-22 10:03:35.153 侵入性电生理学检测对无症状Brugada模式心电图的作用 (点击量:0)

由于在非随机化研究中的结果不一致,对心电图(Brugada pattern,ECG)无症状患者进行侵入性电生理(EP)检测以预测未来心律失常事件的作用尚不清楚。在2017年的一项系统性综述中,仅包括Brugada心电图表现无创性EP检查的患者(6项研究共1138例患者)的研究,大约三分之一的患者在EP检查期间发现可诱发的室性心动过速(VT) 5]。尽管诱导型室速的患者发生心律失常事件的可能性(持续室速,心源性猝死或适当的除颤器治疗)的可能性是其发生率的两倍以上,两组的事件发生率都较低(3.3%对1.6%),差异不是具有统计意义因此,我们不建议在大多数Brugada模式ECG检查无症状患者进行EP测试。此外,总体低事件率令人放心,并表明这些患者未来心律失常事件的风险较低。

BACKGROUND Although large randomized clinical trials have found that primary prevention use of an implantable cardioverter-defibrillator (ICD) improves survival in patients with cardiomyopathy and heart failure symptoms, patients who receive ICDs in practice are often older and have more comorbidities than patients who were enrolled in the clinical trials. In addition, there is a debate among clinicians on the usefulness of electrophysiological study for risk stratification of asymptomatic patients with Brugada syndrome.

AIM Our analysis has 2 objectives. First, to evaluate whether ventricular arrhythmias (VAs) induced with programmed electrostimulation in asymptomatic patients with Brugada syndrome identify a higher risk group that may require additional testing or therapies. Second, to evaluate whether implantation of an ICD is associated with a clinical benefit in older patients and patients with comorbidities who would otherwise benefit on the basis of left ventricular ejection fraction and heart failure symptoms.

METHODS Traditional statistical approaches were used to address 1) whether programmed ventricular stimulation identifies a higher-risk group in asymptomatic patients with Brugada syndrome and 2) whether ICD implantation for primary prevention is associated with improved outcomes in older patients (>75 years of age) and patients with significant comorbidities who would otherwise meet criteria for ICD implantation on the basis of symptoms or left ventricular function RESULTS: Evidence from 6 studies of 1138 asymptomatic patients were identified. Brugada syndrome with inducible VA on electrophysiological study was identified in 390 (34.3%) patients. To minimize patient overlap, the primary analysis used 5 of the 6 studies and found an odds ratio of 2.3 (95% CI: 0.63-8.66; p=0.2) for major arrhythmic events (sustained VAs, sudden cardiac death, or appropriate ICD therapy) in asymptomatic patients with Brugada syndrome and inducible VA on electrophysiological study versus those without inducible VA. Ten studies were reviewed that evaluated ICD use in older patients and 4 studies that evaluated unique patient populations were identified. In our analysis, ICD implantation was associated with improved survival (overall hazard ratio: 0.75; 95% confidence interval: 0.67-0.83; p<0.001). Ten studies were identified that evaluated ICD use in patients with various comorbidities including renal disease, chronic obstructive pulmonary disease, atrial fibrillation, heart disease, and others. A random effects model demonstrated that ICD use was associated with reduced all-cause mortality (overall hazard ratio: 0.72; 95% confidence interval: 0.65-0.79; p<0.0001), and a second "minimal overlap" analysis also found that ICD use was associated with reduced all-cause mortality (overall hazard ratio: 0.71; 95% confidence interval: 0.61-0.82; p<0.0001). In 5 studies that included data on renal dysfunction, ICD implantation was associated with reduced all-cause mortality (overall hazard ratio: 0.71; 95% confidence interval: 0.60-0.85; p<0.001).

9   2018-05-22 10:00:05.6 立体定向放射治疗难治性室性心动过速 (点击量:0)

临床前研究和病例报告表明立体定向放射治疗在一些恶性肿瘤的治疗中很有效,可能对难治性室性心动过速(VT)有效。 在一个单中心病例系列研究中,5例患有先前射频消融失败的结构性心脏病患者(或者不是消融候选者)以及持续性VT,尽管有两种或更多种抗心律失常药物,但立体定向放射治疗可以减少过多的VT负荷 99%,一般耐受性良好。 鉴于患者人群室性心律失常的减少程度有限,而其他治疗方案有限,立体定向放射治疗是一种潜在的有吸引力的治疗方法,但在更大规模的研究中需要额外的有效性和安全性评估。

BACKGROUND Recent advances have enabled noninvasive mapping of cardiac arrhythmias with electrocardiographic imaging and noninvasive delivery of precise ablative radiation with stereotactic body radiation therapy (SBRT). We combined these techniques to perform catheter-free, electrophysiology-guided, noninvasive cardiac radioablation for ventricular tachycardia.

METHODS We targeted arrhythmogenic scar regions by combining anatomical imaging with noninvasive electrocardiographic imaging during ventricular tachycardia that was induced by means of an implantable cardioverter-defibrillator (ICD). SBRT simulation, planning, and treatments were performed with the use of standard techniques. Patients were treated with a single fraction of 25 Gy while awake. Efficacy was assessed by counting episodes of ventricular tachycardia, as recorded by ICDs. Safety was assessed by means ofserial cardiac and thoracic imaging.

RESULTS From April through November 2015, five patients with high-risk, refractory ventricular tachycardia underwent treatment. The mean noninvasive ablation time was 14 minutes (range, 11 to 18). During the 3 months before treatment, the patients had a combined history of 6577 episodes of ventricular tachycardia. During a 6-week postablation "blanking period" (when arrhythmias may occur owing to postablation inflammation), there were 680 episodes of ventricular tachycardia. After the 6-week blanking period, there were 4 episodes of ventricular tachycardia over the next 46 patient-months, for a reduction from baseline of 99.9%. A reduction in episodes of ventricular tachycardia occurred in all five patients. The mean left ventricular ejection fraction did not decrease with treatment. At 3 months, adjacent lung showed opacities consistent with mild inflammatory changes, which had resolved by 1 year.

CONCLUSIONS In five patients with refractory ventricular tachycardia, noninvasive treatment with electrophysiology-guided cardiac radioablation markedly reduced the burden of ventricular tachycardia. (Funded by Barnes-Jewish Hospital Foundation and others.).

10   2018-05-22 09:58:48.52 心脏装置患者的MRI安全性 (点击量:0)

永久性起搏器或植入式心脏复律除颤器(ICD)患者的磁共振成像(MRI)潜在风险包括编程改变,起搏异常和导线中的感应电流。在一系列1509名患有老一代起搏器或ICD的患者(例如,那些不特别符合食品和药物管理局规定的MRI-条件标准或“传统”设备的患者)中进行胸部或非胸部MRI检查以及随访1年,没有临床意义的事件。虽然这个和以前的报道令人放心,但是在MRI和成像过程中的患者监护之前和之后,可以使用除颤器和代码手推车,非MRI有条件的起搏器或ICD需要采取预防措施,包括设备编程。如果检查对于疾病的诊断或治疗是必要的和必要的,那么在非MRI有条件的永久起搏器或ICD的患者中可以进行MR成像,只要采取了特定的预防措施。

BACKGROUND Patients who have pacemakers or defibrillators are often denied the opportunity to undergo magnetic resonance imaging (MRI) because of safety concerns, unless the devices meet certain criteria specified by the Food and Drug Administration (termed "MRI-conditional" devices).

METHODS We performed a prospective, nonrandomized study to assess the safety of MRI at a magnetic field strength of 1.5 Tesla in 1509 patients who had a pacemaker (58%) or an implantable cardioverter-defibrillator (42%) that was not considered to be MRI-conditional (termed a "legacy" device). Overall, the patients underwent 2103 thoracic and nonthoracic MRI examinations that were deemed to be clinically necessary. The pacing mode was changed to asynchronous mode for pacing-dependent patients and to demand mode for other patients. Tachyarrhythmia functions were disabled. Outcome assessments included adverse events and changes in the variables that indicate lead and generator function and interaction with surrounding tissue (device parameters).

RESULTS No long-term clinically significant adverse events were reported. In nine MRI examinations (0.4%; 95% confidence interval, 0.2 to 0.7), the patient's device reset to a backup mode. The reset was transient in eight of the nine examinations. In one case, a pacemaker with less than 1 month left of battery life reset to ventricular inhibited pacing and could not be reprogrammed; the device was subsequently replaced. The most common notable change in device parameters (>50% change from baseline) immediately after MRI was a decrease in P-wave amplitude, which occurred in 1% of the patients. At long-term follow-up (results of which were available for 63% of the patients), the most common notable changes from baseline were decreases in P-wave amplitude (in 4% of the patients), increases in atrial capture threshold (4%), increases in right ventricular capture threshold (4%), and increases in left ventricular capture threshold (3%). The observed changes in lead parameters were not clinically significant and did not require device revision or reprogramming.

CONCLUSIONS We evaluated the safety of MRI, performed with the use of a prespecified safety protocol, in 1509 patients who had a legacy pacemaker or a legacy implantable cardioverter-defibrillator system. No long-term clinically significant adverse events were reported. (Funded by Johns Hopkins University and the National Institutes of Health; ClinicalTrials.gov number, NCT01130896 .).