Comparative Effectiveness of Patient-Driven versus Standardized Diabetes Shared Medical Appointments: A Pragmatic Cluster Randomized Trial.

BACKGROUND: Diabetes self-management education and support can be effectively and efficiently delivered in primary care in the form of shared medical appointments (SMAs). Comparative effectiveness of SMA delivery features such as topic choice, multi-disciplinary care teams, and peer mentor involvement is not known. OBJECTIVE: To compare effects of standardized and patient-driven models of diabetes SMAs on patient-level diabetes outcomes. DESIGN: Pragmatic cluster randomized trial. PARTICIPANTS: A total of 1060 adults with type 2 diabetes in 22 primary care practices. INTERVENTIONS: Practice personnel delivered the 6-session Targeted Training in Illness Management (TTIM) curriculum using either standardized (set content delivered by a health educator) or patient-driven SMAs (patient-selected topic order delivered by health educators, behavioral health providers [BHPs], and peer mentors). MAIN MEASURES: Outcomes included self-reported diabetes distress and diabetes self-care behaviors from baseline and follow-up surveys (assessed at 1st and final SMA session), and HbA1c, BMI, and blood pressure from electronic health records. Analyses used descriptive statistics, linear regression, and linear mixed models. KEY RESULTS: Both standardized and patient-driven SMAs effectively improved diabetes distress, self-care behaviors, BMI (- 0.29 on average), and HbA1c (- 0.45% (mmol/mol) on average, 8.3 to 7.8%). Controlling for covariates, there was a small, significant effect of condition on overall diabetes distress in favor of standardized SMAs (F(1,841) = 4.3, p = .04), attributable to significant effects of condition on emotion and regimen distress subscales. There was a small, significant effect of condition on diastolic blood pressure in favor of standardized SMAs (F(1,5199) = 4.50, p = .03). There were no other differences between conditions. CONCLUSIONS: Both SMA models using the TTIM curriculum yielded significant improvement in diabetes distress, self-care, and HbA1c. Patient-driven diabetes SMAs involving BHPs and peer mentors and topic selection did not lead to better clinical or patient-reported outcomes than standardized diabetes SMAs facilitated by a health educator following a set topic order. NIH TRIAL REGISTRY NUMBER: NCT03590041.

Caudocranial transseptal approach for placement of endocardial left ventricular leads.

Cardiac resynchronization therapy (CRT) is associated with improvement in the quality of life, hospitalization rates, and mortality in patients with left ventricular dysfunction and evidence of the right ventricle-left ventricle (RV-LV) desynchrony. Implant failure rates and patient outcomes have improved with the advent of quadripolar leads, yet alternatives to traditional coronary sinus (CS) LV lead placement is sought for in a subset of advanced heart failure patients with difficult CS anatomy, phrenic nerve stimulation or in nonresponders. Endocardial left ventricular pacing (EnLVP) in chronically anticoagulated patients has been reported as an alternative using different approaches, techniques, and tools with acceptable short and long term adverse events. We present a case of successful EnLVP achieved for CRT using standard techniques and commonly available tools in a patient on chronic direct oral anticoagulation with recurrent heart failure admissions who failed traditional epicardial LV pacing.

Stakeholder engagement in diabetes self-management: patient preference for peer support and other insights.

Background: Self-management support (SMS) for patients with diabetes can improve adherence to treatment, mitigate disease-related distress, and improve health outcomes. Translating this evidence into real-world practice is needed, as it is not clear which SMS models are acceptable to patients, and feasible and sustainable for primary care practices. Objective: To use the Boot Camp Translation (BCT) method to engage patient, practice, community resource and research stakeholders in translation of evidence about SMS and diabetes distress into mutually acceptable care models and to inform patient-centred outcomes research (PCOR). Participants: Twenty-seven diabetes care stakeholders, including patients and providers from a local network of federally qualified health centres participated. Methods: Stakeholders met in-person and by conference call over the course of 8 months. Subject matter experts provided education on the diabetes SMS evidence. Facilitators engaged the group in discussions about barriers to self-management and opportunities for improving delivery of SMS. Key Results: BCT participants identified lack of social support, personal resources, trust, knowledge and confidence as barriers to diabetes self-management. Intervention opportunities emphasized peer support, use of multidisciplinary care teams and centralized systems for sharing information about community and practice resources. BCT informed new services and a PCOR study proposal. Conclusions: Patients and family engaged in diabetes care research value peer support, group visits, and multidisciplinary care teams as key features of SMS models. SMS should be tailored to an individual patient's health literacy. BCT can be used to engage multiple stakeholders in translation of evidence into practice and to inform PCOR.

Anatomic relationships between the coronary venous system, surrounding structures, and the site of origin of epicardial ventricular arrhythmias.

BACKGROUND: Epicardial left ventricular (LV) idiopathic ventricular arrhythmias (VAs) can be approached via the pericardial space, the coronary venous system (CVS), or other surrounding structures. The anatomic relationships between epicardial sites of origin (SOO) of VAs and surrounding anatomic structures have not been systematically described. METHODS AND RESULTS: In 17 patients with idiopathic epicardial VAs, the relationships between the SOO and the CVS and other neighboring anatomic structures were assessed by computed tomographic angiography. Ablation was successful in 12/17 patients (71%). In 10/17 patients, the SOO was at a distance of ≤4 mm from a coronary artery. The SOO was closer to the CVS (2.1 ± 1.5 mm) than to the pericardial space (9.7 ± 3.7 mm) or the LV endocardium (7.7 ± 2.7 mm). Successful ablations were carried out from the CVS (n = 3), the CVS and LV endocardium (n = 5), the CVS and the aortic cusp (n = 1), the CVS, the LV endocardium, and the aortic cusp (n = 1), the LV endocardium (n = 1), and the CVS and the pericardial space (n = 1). In the remaining 5 patients, a subxyphoid pericardial ablation procedure was attempted and failed in all 5 patients. CONCLUSION: The CVS is closer to the SOO of epicardial idiopathic VAs than the pericardial space, the ventricular endocardium, and the aortic cusps. Given the proximity to coronary arteries at the SOO, radiofrequency energy often cannot be safely delivered to eliminate a VA and ablation may also need to be performed from adjacent structures. A subxyphoid pericardial ablation procedure has a low probability of success in patients with idiopathic epicardial VAs.

A billiard ball in the left atrium.

An 84-year-old woman with a history of severe systolic heart failure, a mechanical mitral valve, and atrial fibrillation presented to the hospital with syncope and is found to have a free-floating intracardiac mass on transthoracic echocardiogram that was absent 5 months earlier. Real time three-dimensional (3D) transesophageal echocardiography (TEE) images reveal a billiard-ball-looking mass thought to be a large left atrial thrombus causing syncope by transiently obstructing the mitral valve orifice. Real time 3D TEE offers several potential advantages for the evaluation of intracardiac masses.

Impact of acute gain on clinical outcomes of patients treated with sirolimus-eluting stent. - A sub-analysis study from the STLLR trial-.

BACKGROUND: Geographical miss (GM), representing suboptimal drug-eluting stent deployment, is associated with an increased risk of target lesion revascularization (TLR) and myocardial infarction. The impact of suboptimal stenting techniques on clinical outcomes in diabetics remains unknown. METHODS AND RESULTS: Stent deployment Techniques on cLinicaL outcomes of patients treated with the cypheR(TM) stent (STLLR) is the first multicenter, large trial to prospectively evaluate outcomes associated with sirolimus-eluting stent (SES) deployment techniques. Axial GM and longitudinal GM (LGM), defined as a balloon injured segment or a diseased segment not covered by a SES, were assessed by an independent core laboratory. One-year outcomes between diabetics and non-diabetics and their relationship with GM were assessed. This substudy included 1,336 patients, 28.8% with diabetes. In non-LGM patients, TLR was similarly low in both diabetics and non-diabetics (2.0% vs. 2.0%, P=NS). However, TLR increased 4.1 times in diabetics (8.0%) and 1.9 times in non-diabetics (3.8%) in the presence of LGM (P=0.03). Axial GM had no impact on outcomes. By univariate analysis, stent length, acute gain, and LGM were the predictors of TLR in the total cohort. However, by multivariate analysis, acute gain was the only predictor of TLR (P=0.03), independently of LGM or diabetes. CONCLUSIONS: Acute gain is the exclusive predictor of TLR after SES implantation. Particularly in diabetics, the negative impact of LGM on TLR seems to be amplified. Diligent SES deployment for larger acute gain is critical to improve clinical outcomes.

Case series: Tension pneumothorax complicating narrow-bore enteral feeding tube placement.

Frequently, narrow-bore feeding tubes are placed in critically ill hospitalized patients without difficulty. However, due to the simplicity and relative ease of bedside placement of feeding tubes, complications, including life threatening, are often minimized. We report 3 cases of severe pleuropulmonary complications after routine bedside placement of a narrow-bore enteral feeding tubes and a review of the literature. These episodes have not only prompted our adoption of a new policy specifying the routine use of ultrasound to guide feeding tube placement in obtunded or mechanically ventilated patients but also offer recommendations post-removal of misplaced feeding tubes.

Prognostic utility of 64-slice computed tomography in patients with suspected but no documented coronary artery disease.

AIMS: Although multislice computed tomography (MSCT) detects obstructive coronary artery disease (CAD) with high diagnostic accuracy, there is a paucity of long-term prognostic data. We sought to assess the incremental prognostic value of 64-slice CT in patients with suspected but no documented CAD. METHODS AND RESULTS: Coronary MSCT was performed on 227 individuals (61% men, mean age 54 +/- 12 years, 63% with intermediate pre-test probability) without documented CAD, referred for coronary evaluation. Coronary artery disease by MSCT was categorized as follows: none or mild CAD (<50%, n = 172), > or =50% in one vessel (n = 23), two vessels [or in the proximal left anterior descending (LAD), n = 12], and three vessels (or in two vessels including the proximal LAD or left main, n = 20). Baseline risk factors, length of follow-up, and major adverse cardiac events (MACE), including cardiac death, myocardial infarction (MI), and coronary revascularization were recorded. Over a mean follow-up of 2.3 +/- 0.8 years, there were 18 MACE [including four hard events (one cardiac death and three MIs)]. Also, patients with one or more vessel obstructive CAD had increased hard events compared with those with less than one-vessel disease (log-rank statistic P-value 0.01). One or more vessel obstructive CAD was a significant predictor of MACE on univariable and multivariable Cox proportional survival analysis [hazard ratios 29.1 (6.7-126.6) and 9.82 (3.58-27.01), respectively, both P < 0.0001]. In 172 patients, with no or mild CAD, there was 99% freedom from MACE during follow-up. CONCLUSION: Multislice computed tomography-classified extent of CAD provides incremental prognostic information in patients with suspected but no documented CAD.

Association of total cholesterol/ high-density lipoprotein cholesterol ratio with proximal coronary atherosclerosis detected by multislice computed tomography.

The authors assessed the association between an elevated total cholesterol to high-density lipoprotein cholesterol (TC/HDL-C) ratio (> or = 4) and proximal coronary artery disease (CAD), as observed on multislice computed tomography. Coronary multislice computed tomographic angiography (96% on 40- or 64-slice) was performed in 295 individuals (39% women; mean age, 54 +/- 13 years) without documented CAD who were referred for coronary evaluation. Significant CAD was defined as > or = 50% stenosis in the left main, proximal left anterior descending, or > or = 2 epicardial vessels. Proximal plaque was defined as presence of any plaque in left main or proximal left anterior descending vessels. Individuals with an elevated TC/HDL-C ratio vs those without had a higher prevalence of proximal plaque (62% vs 48%, P = .04) and significant CAD (19% vs 9%, P = .009). On multivariate logistic regression analysis, only age, sex, and TC/HDL-C ratio > or = 4 were associated with significant CAD and proximal plaque.

Here one year, gone the next? Investigating persistence of frequent emergency department attendance: a retrospective study in Australia.

OBJECTIVES: Patients are presenting to emergency departments (EDs) with increasing complexity at rates beyond population growth and ageing. Intervention studies target patients with 12 months or less of frequent attendance. However, these interventions are not well targeted since most patients do not remain frequent attenders. This paper quantifies temporary and ongoing frequent attendance and contrasts risk factors for each group. DESIGN: Retrospective population-based study using 10 years of longitudinal data. SETTING: An Australian geographic region that includes metropolitan and rural EDs. PARTICIPANTS: 332 100 residents visited any ED during the study period. MAIN OUTCOME MEASURE: Frequent attendance was defined as seven or more visits to any ED in the region within a 12-month period. Temporary frequent attendance was defined as meeting this threshold only once, and ongoing more than once. Risk factors for temporary and ongoing frequent attenders were identified using logistic regression models for adults and children. RESULTS: Of 8577 frequent attenders, 80.1% were temporary and 19.9% ongoing (12.9% repeat, 7.1% persistent). Among adults, ongoing were more likely than temporary frequent attenders to be young to middle aged (aged 25-64 years), and less likely to be from a high socioeconomic area or be admitted. Ongoing frequent attenders had higher rates of non-injury presentations, in particular substance-related (OR=2.5, 99% CI 1.1 to 5.6) and psychiatric illness (OR=2.9, 99% CI 1.8 to 4.6). In comparison, children who were ongoing were more likely than temporary frequent attenders to be aged 5-15 years, and were not more likely to be admitted (OR=2.7, 99% CI 0.7 to 10.9). CONCLUSIONS: Future intervention studies should distinguish between temporary and ongoing frequent attenders, develop specific interventions for each group and include rigorous evaluation.

Association of coronary atherosclerosis detected by multislice computed tomography and traditional risk-factor assessment.

Framingham risk score is an office-based tool used for long-term coronary heart disease risk stratification. Most acute coronary events occur in association with proximal nonobstructive atherosclerotic plaque. Multislice computed tomography detects both obstructive coronary artery disease (CAD) and proximal atherosclerotic plaque with high accuracy. The association of Framingham risk score with obstructive CAD and proximal atherosclerotic plaque was tested. Coronary multislice computed tomography was performed in 295 patients (61% men, mean age 54 +/- 13 years) without documented CAD referred for evaluation of cardiac symptoms. Framingham risk score was computed and patients were stratified according to 10-year risk (n = 213 [72%] low, n = 74 [25%] intermediate, and n = 8 [3%] high). Obstructive CAD was defined as > or =50% stenosis in > or =1 epicardial coronary artery. Proximal atherosclerotic plaque was defined as calcified or noncalcified plaque in the left main or proximal left anterior descending artery. In the low- and intermediate-Framingham risk score groups, there was a high frequency of proximal atherosclerotic plaque (44% and 75%) and obstructive CAD (16% and 34%), although both findings were more prevalent in the high-Framingham risk score group (63% for atherosclerotic plaque, 88% for obstructive CAD), respectively. Proximal atherosclerotic plaque was noncalcified in approximately 13 of patients. In women (n = 114) and younger (<55 years) patients (n = 148), most (93% and 91%, respectively) had a low Framingham risk score. There were 48 women and 51 younger patients with proximal atherosclerotic plaque, of whom only 40% (in each group) were on statin therapy. In conclusion, of patients with a low and intermediate Framingham risk score, a significant proportion had proximal atherosclerotic plaque or obstructive CAD.

Presence of carotid and peripheral arterial disease in patients with left main disease.

Left main (LM) coronary disease, carotid artery disease, and peripheral arterial disease each reflects advanced atherosclerosis. The frequency of their coexistence in the same patient has not been fully elucidated. All coronary angiograms obtained at the Cleveland Clinic from November 2003 to October 2005 were analyzed for presence of LM stenosis > or =50%. Patients with previous coronary artery bypass graft surgery were excluded. Patients with available carotid ultrasound and ankle-brachial indexes formed the analysis cohorts. A total of 10,298 coronary angiograms were obtained in 9,715 patients. There were 186 patients with LM disease and 1,913 patients without LM disease with carotid artery ultrasound data. There were 29 patients with LM disease and 604 patients without LM disease with available ankle-brachial indexes. Patients with significant LM disease more frequently had associated carotid stenosis > or =60% compared with patients without LM disease (31.2% vs 15.2%, p <0.0001). Patients with LM disease had lower mean ankle-brachial indexes compared with patients without LM disease (0.78 vs 0.87, p = 0.042). In conclusion, compared with patients without LM disease, patients with LM disease have a higher burden of advanced atherosclerosis as evidenced by a higher prevalence of significant carotid stenosis and lower ankle-brachial indexes.

Cleaning and Sterilization of Used Cardiac Implantable Electronic Devices With Process Validation: The Next Hurdle in Device Recycling.

OBJECTIVES: This study sought to develop a validated, reproducible sterilization protocol, which could be used in the reprocessing of cardiac implantable electronic devices (CIEDs). BACKGROUND: Access to cardiac CIED therapy in high-income and in low- and middle-income countries varies greatly. CIED reuse may reduce this disparity. METHODS: A cleaning and sterilization protocol was developed that includes washing CIEDs in an enzymatic detergent, screw cap and set screw replacement, brushing, inspection, and sterilization in ethylene oxide. Validation testing was performed to assure compliance with accepted standards. RESULTS: With cleaning, the total mean bioburden for each of 3 batches of 10 randomly chosen devices was reduced from 754 to 10.1 colony-forming units. After sterilization with ethylene oxide, with 3 half-cycle and 3 full-cycle processes, none of the 90 biological indicator testers exhibited growth after 7 days. Through cleaning and sterilization, protein and hemoglobin concentrations were reduced from 99.2 to 1.42 µg/cm2 and from 21.4 to 1.03 µg/cm2, respectively. Mean total organic carbon residual was 1.44 parts per million (range 0.36 to 2.9 parts per million). Endotoxin concentration was not detectable at the threshold of <0.03 endotoxin units/ml or <3.0 endotoxin units/device. Cytotoxicity and intracutaneous reactivity tests met the standards set by the Association for Advancement of Medical Instrumentation and the International Organization for Standardization. CONCLUSIONS: CIEDs can be cleaned and sterilized according to a standardized protocol achieving a 12-log reduction of inoculated product, resulting in sterility assurance level of 10-6.

The influence of salinity on acute nickel toxicity to the two euryhaline fish species, Fundulus heteroclitus and Kryptolebias marmoratus.

Nickel (Ni) is a common pollutant found in aquatic environments and may be harmful at elevated concentrations. Increasing salinity has been shown to decrease the bioavailability and toxicity of other metals to aquatic organisms. In the present study, acute Ni toxicity experiments (96-h) were conducted at various salinities (0-36 ppt) to determine the effects of salinity on Ni toxicity to 2 euryhaline fish species, Kryptolebias marmoratus and Fundulus heteroclitus. Nickel concentrations causing lethality to 50% of the fish ranged from 2 mg/L in moderately hard freshwater to 66.6 mg/L in 36 ppt saltwater. Nickel toxicity to F. heteroclitus decreased linearly with increasing salinity; however, Ni toxicity to K. marmoratus was only lowered by salinities above 6 ppt, demonstrating potential physiological differences between the 2 species when they are functioning as freshwater fish. Furthermore, the authors investigated the influence of Mg(2+) , Ca(2+) , Na(+) , and Cl(-) on Ni toxicity to F. heteroclitus. Freshwater with up to 120 mg/L Ca(2+) as CaSO4 , 250 mg/L Mg(2+) as MgSO4 , or 250 mg/L Na(+) as NaHCO3 did not provide protection against Ni toxicity. Alternatively, 250 mg/L Na(+) , as NaCl, was protective against Ni toxicity; and the extent of protection was similar to that demonstrated from salt water with the same Cl(-) concentration. These results suggest that Cl(-) is the predominant ion responsible for reducing Ni toxicity to K. marmoratus and F. heteroclitus in higher salinity waters.

Characteristics of atrial tachycardia due to small vs large reentrant circuits after ablation of persistent atrial fibrillation.

BACKGROUND: While macroreentrant atrial tachycardias (ATs) have been reasonably well described, little is known about small reentrant circuits. OBJECTIVE: To compare characteristics of large and small reentrant circuits after ablation of persistent atrial fibrillation. METHODS: Seventy-seven patients (age 61±10 years; left atrium 46±6 mm; ejection fraction 0.52±0.13) underwent a procedure for postablation AT. The p-wave duration, circuit size, electrogram characteristics, and conduction velocity were determined. RESULTS: AT was due to macroreentry in 62 (80%) patients, a small reentrant circuit in 13 (17%), and a focal mechanism in 2 (3%). The p-wave duration during small reentrant ATs was shorter than that during macroreentry (174±12 ms vs 226±22 ms; P<.0001). The duration of fractionated electrograms at the critical site was longer in small vs large circuits (167±43 ms vs 98±38 ms, respectively; P<.0001) and accounted for a greater percentage of the tachycardia cycle length (59%±18% vs 38%±14%, respectively; P<.0001). The mean diameters of macroreentrant and small reentrant circuits were 44±7 and 26±11 mm, respectively (P<.0001). The mean conduction velocity along the small circuits was lower (0.5±0.2 m/s vs 1.2±0.3 m/s; P<.0001). Catheter ablation eliminated the AT in all 77 patients. CONCLUSIONS: AT due to a small reentrant circuit after ablation of atrial fibrillation may be distinguished from macroreentry by a shorter p-wave duration and the presence of long-duration electrograms at the critical site owing to extremely slow conduction. These features may aid the clinician in the mapping of postablation ATs.

Dabigatran vs warfarin for radiofrequency catheter ablation of atrial fibrillation.

BACKGROUND: It is not clear whether dabigatran is as safe and effective as uninterrupted anticoagulation with warfarin during radiofrequency catheter ablation (RFA) of atrial fibrillation (AF). OBJECTIVE: To compare the safety and efficacy of dabigatran by using a novel administration protocol and uninterrupted anticoagulation with warfarin for periprocedural anticoagulation in patients undergoing RFA of AF. METHODS: In this case-control analysis, 763 consecutive patients (mean age 61±10 years) underwent RFA of AF using dabigatran (N = 191) or uninterrupted warfarin (N = 572) for periprocedural anticoagulation. In all patients, anticoagulation was started≥4 weeks before RFA. Dabigatran was held after the morning dose on the day before the procedure and resumed 4 hours after vascular hemostasis was achieved. RESULTS: A transesophageal echocardiogram performed in all patients receiving dabigatran did not demonstrate an intracardiac thrombus. There were no thromboembolic complications in either group. The prevalence of major (4 of 191, 2.1%) and minor (5 of 191, 2.6%) bleeding complications in the dabigatran group were similar to those in the warfarin group (12 of 572, 2.1%; P = 1.0 and 19 of 572, 3.3%; P = .8, respectively). Pericardial tamponade occurred in 2 of 191 (1%) patients in the dabigatran group and in 7 of 572 (1.2%) patients in the warfarin group (P = 1.0). All patients who had a pericardial tamponade, including 2 in the dabigatran group, had uneventful recovery after perdicardiocentesis. On multivariate analysis, international normalized ratio (odds ratio [OR] 4.0; 95% confidence interval [CI] 1.1-15.0; P = .04), clopidogrel use (OR 4.2; 95% CI 1.5-12.3; P = .01), and CHA2DS2-VASc score (OR 1.4; 95% CI 1.1-1.8; P = .01) were the independent risk factors of bleeding complications only in the warfarin group. CONCLUSIONS: When held for approximately 24 hours before the procedure and resumed 4 hours after vascular hemostasis, dabigatran appears to be as safe and effective as uninterrupted warfarin for periprocedural anticoagulation in patients undergoing RFA of AF.

International participation in cardiovascular randomized controlled trials sponsored by the National Heart, Lung, and Blood Institute.

OBJECTIVES: The aim of this study was to describe international enrollment and participation in National Institutes of Health (NIH)-sponsored cardiovascular randomized controlled trials (RCTs). BACKGROUND: RCTs provide the evidence base for major societal guidelines and profoundly influence patient care in the United States. Increased international involvement in clinical trials has been observed, but the rate of international enrollment in NIH-sponsored cardiovascular RCTs has not been described. METHODS: The NIH registry of clinical trials was searched for phase III or IV cardiovascular RCTs funded by the National Heart, Lung, and Blood Institute. Studies with outcomes of myocardial infarction, stroke, or death published between 1997 and 2009 were included. Rates of international enrollment were obtained from published data or personal communication with corresponding authors. RESULTS: Twenty-four studies met all inclusion criteria. Nineteen trials including 151,682 patients had international participation (IP), with median IP of 9.5% (range 0% to 100%). Coronary artery disease trials (11 studies) had nearly 50% international enrollment. High-risk trials and trials testing acute interventions tended to have higher rates of IP. CONCLUSIONS: Cardiovascular RCTs sponsored by the National Heart, Lung, and Blood Institute have substantial rates of international enrollment, particularly coronary artery disease trials. Given questions of applicability and ethical and financial considerations, IP in U.S. clinical trials deserves further scrutiny.

Impact of QRS duration on clinical event reduction with cardiac resynchronization therapy: meta-analysis of randomized controlled trials.

BACKGROUND: Cardiac resynchronization therapy (CRT) is effective in reducing clinical events in patients with heart failure and prolonged QRS interval. Studies using surrogate measures and subgroup analysis of large trials suggest that only patients with severely prolonged QRS benefit from CRT. Our objective was to determine whether the effect of CRT on adverse clinical events (eg, death, hospitalizations) is different in patients with moderately (ie, 120 to 149 milliseconds) [corrected] vs severely (ie, ≥150 milliseconds) prolonged QRS duration. METHODS: Searches of MEDLINE, SCOPUS, and Cochrane databases were conducted for randomized controlled CRT trials. Trials reporting clinical events according to different QRS ranges were identified. Five randomized trials fulfilling the inclusion criteria (total patients, n = 5813) were included in the meta-analysis. RESULTS: In patients with severely prolonged QRS, there was a reduction in composite clinical events with CRT (risk ratio, 0.60; 95% confidence interval [CI], 0.53-0.67) (P < .001). In contrast, there was no benefit of CRT in patients with moderately prolonged QRS (RR, 0.95; 95% CI, 0.82-1.10) (P = .49), resulting in a significantly different impact of CRT in the 2 QRS groups (P < .001). There was a significant relationship between baseline QRS duration and risk ratio (P < .001) with benefit of CRT appearing at a QRS of approximately 150 milliseconds and above. The differential response of the 2 QRS groups was evident for all New York Heart Association classes. CONCLUSIONS: Cardiac resynchronization therapy was effective in reducing adverse clinical events in patients with heart failure and a baseline QRS interval of 150 milliseconds or greater, but CRT did not reduce events in patients with a QRS of less than 150 milliseconds. These findings have implications for the selection of patients for CRT.