Safety of Magnetic Resonance Imaging in Patients with Cardiac Devices

Saman Nazarian, Rozann Hansford, Amir A. Rahsepar, et al

N Engl J Med 2017;377:2555-64.

DOI: 10.1056/NEJMoa1604267

BACKGROUND 背景

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).

植入起搏器或除颤器的患者常常因安全方面的顾虑无法进行核磁共振(MRI)检查，除非该设备符合FDA有关标准（称为MRI兼容设备）。

METHODS 方法学

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).

我们进行了一项前瞻非随机研究，对1509名植入起搏器(58%)或植入式心脏复律除颤器的患者（这些植入装置并非MRI兼容设备），评估核磁场强度1.5 Tesla下MRI的安全性。根据临床需要，入选患者共进行2103次胸部及非胸部MRI检查。对于依赖起搏的患者，起搏模式更换为非同步模式，其他患者则更换为按需模式。快速性心律失常功能关闭。预后评估包括不良事件，以及提示电极及发生器功能或与周围组织相互作用的参数改变（设备参数）。

RESULTS 结果

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.

未报告临床重要的长期不良事件。在9次MRI检查过程中（0.4%; 95% 可信区间，0.2 to 0.7），患者的植入设备重置为后备模式，其中8次重置为一过性。在1例起搏器电池寿命不足1个月的患者，该起搏器重置为心室抑制型起搏且无法重新设置；随后更换该装置。MRI检查结束即刻，设备参数最常见的改变（从基线水平改变> 50%）为P波波幅减低，大约1%的患者出现。长期随访（63%的患者结果完整）期间，与基线水平相比最常见的改变为P波波幅减低（4%的患者），心房夺获阈值升高(4%)，右心室夺获阈值升高(4%)，以及左心室夺获阈值升高(3%)。观察到的电极参数改变没有临床意义，无需设备调整或重新设置。

CONCLUSIONS 结论

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.)

我们采用预先设置的安全方案，对于1509名植入非MRI兼容性起搏器或植入式心脏复律除颤器的患者，评价了MRI检查的安全性。未报告临床重要的长期不良事件。

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