Cardiac resynchronization therapy (CRT) reduces morbidity and mortality among selected patients with left ventricular systolic dysfunction and severe heart failure symptoms despite guideline-directed medical therapy (GDMT). Contemporaneous guidelines provided clear recommendations regarding selection of patients for CRT, including that all patients should first receive GDMT with β blockers and renin-angiotensin axis antagonists. Prevalence of GDMT among real-world patients receiving CRT defibrillators (CRT-D) has not been well studied. We identified 45,392 patients in the National Cardiovascular Data Registry Implantable Cardioverter-Defibrillator Registry who underwent first CRT-D implantation for primary prevention of sudden death from January 2006 to June 2008. We calculated the proportion of patients with contemporaneous class I guideline indications for CRT-D, the proportion receiving GDMT for heart failure, and the proportion receiving GDMT who had class I guideline indications for CRT-D. Among patients without contraindications, 87% were prescribed β blockers, 78% an angiotensin-converting enzyme inhibitor or an angiotensin II receptor inhibitor, and 70% both a β blocker and an angiotensin-converting enzyme or angiotensin II receptor inhibitor at discharge. Finally, 50% of patients met class I guideline indications and were prescribed GDMT at discharge; 9% neither met class I indications nor were prescribed GDMT at discharge. The major limitation of this study is the lack of dosage information in the Implantable Cardioverter-Defibrillator Registry and lack of prescribing information at times other than discharge. In conclusion, many patients receiving CRT-D are not receiving GDMT at discharge. Ensuring that all patients receiving CRT-D are also receiving GDMT appears to be a quality improvement target.
There is a large body of evidence from randomized controlled trials that shows mortality benefit with the use of β-blocker and angiotensin-converting enzyme inhibitor (ACE-I) therapies in patients with systolic heart failure. Although the mortality benefit is less clear for angiotensin II receptor (ARB) inhibitors, ARB agents are considered an acceptable substitute when ACE-I agents are not tolerated. Current guidelines for management of heart failure in adults recommend β blockers in combination with either an ACE-I or an ARB as part of guideline-directed medical therapy (GDMT). The emphasis on optimal GDMT as a prerequisite before device implantation is in large part due to the proved mortality benefit in patients with left ventricular systolic dysfunction. Fein et al demonstrated that nearly 1 in 4 patients undergoing cardiac resynchronization therapy (CRT) implantation did not meet contemporaneous guideline recommendations. However, the extent to which patients are receiving GDMT in the setting of CRT implantation is less well known. Therefore, our aim was to determine the percentage of patients enrolled in the National Cardiovascular Data Registry Implantable Cardioverter-Defibrillator (ICD) Registry who received CRT devices with defibrillator (CRT-D) capability who were receiving GDMT.
Methods
Analyses in this study were based on data contained in the ICD Registry, a Centers for Medicare and Medicaid Services–mandated national database developed in collaboration with American College of Cardiology Foundation and the Heart Rhythm Society. Detailed data were collected on each implantation. Selected heart failure–specific elements are listed in Table 1 , with a full list of elements available at http://www.ncdr.com/WebNCDR/ICD/home/datacollection .
| Data Element | Response Type |
|---|---|
| Clinical characteristics and history: | |
| Heart failure | Yes/no |
| New York Heart Association Functional class | I–IV |
| Non-ischemic dilated cardiomyopathy | Yes/no |
| Prior heart failure hospitalization | Yes/no |
| Prior heart transplant | Yes/no |
| On heart transplant waiting list | Yes/no |
| Ischemic heart disease | Yes/no |
| Left ventricular ejection fraction | % |
| QRS duration | In milliseconds |
| Discharge medications: | |
| Angiotensin converting enzyme inhibitor | Yes/no |
| Angiotensin II receptor inhibitor | Yes/no |
| Beta-blocker | Yes/no |
| Diuretic | Yes/no |
| Digoxin | Yes/no |
| Hydralazine | Yes/no |
| Long acting nitrate | Yes/no |
The population of interest was patients in the ICD Registry who received CRT-D implantations from January 2006 to June 2008. The study period was chosen to be after the publication of the 2005 American College of Cardiology/American Heart Association guideline update and before the adoption of the 2008 American College of Cardiology/American Heart Association/Heart Rhythm Society Device-Based Therapy Guideline. This represents a period when there were no major updates in the guidelines or evidence base for CRT. The stability in the medical literature provided a time window in which indications for CRT implantation were stable and should have led to consistent characteristics in patients receiving CRT devices.
Baseline characteristics of the study population were examined. Simple proportions were calculated to determine prevalence of categorical variables, whereas mean and standard deviation were calculated for continuous variables. Simple proportions were also calculated to determine the proportion of patients who were receiving specific medical therapies and the proportion of patients who had specific clinical characteristics.
Results
We identified 105,543 CRT-D implantations in 104,648 patients from January 2006 to June 2008 in 1,300 facilities. After excluding indications that were not primary prevention, patients with a previous ICD or pacemaker, clinical criteria that warranted implantation for secondary prevention (syncope, sustained ventricular tachycardia, cardiac arrest, or transvenous pacing), and patients with missing data, our analysis cohort consisted of 45,392 patients ( Figure 1 ). Baseline characteristics in the study cohort were examined and are presented in Table 2 .
| Variable | Number (%) or Mean ± SD |
|---|---|
| Admission characteristics | |
| Age: mean ± SD (years) | 69.34 ± 11.52 |
| Female | 14279 (31.46%) |
| White | 37472 (82.55%) |
| Black | 5511 (12.14%) |
| Other | 2409 (5.31%) |
| Hispanic ethnicity | 2555 (5.63%) |
| Insurance payor | |
| Government: Medicare | 32773 (72.20%) |
| Government: Medicaid | 1722 (3.79%) |
| Government: other | 387 (0.85%) |
| Commercial | 6762 (14.90%) |
| Managed care | 2847 (6.27%) |
| Other | 901 (1.98%) |
| Reason for hospitalization | |
| Admitted for this procedure | 31154 (68.63%) |
| Hospitalized-cardiac | 8532 (18.80%) |
| Hospitalized-non-cardiac | 4750 (10.46%) |
| Missing or unknown | 956 (2.11%) |
| Congestive heart failure | 43413 (95.64%) |
| Current New York Heart Association class | |
| Class I | 678 (1.49%) |
| Class II | 5281 (11.63%) |
| Class III | 35968 (79.24%) |
| Class IV | 3465 (7.63%) |
| Atrial fibrillation/atrial flutter | 13837 (30.48%) |
| Ventricular tachycardia | 8159 (17.97%) |
| Sinus node dysfunction | 10306 (22.70%) |
| Cardiac transplantation | 77 (0.17%) |
| Non-ischemic dilated cardiomyopathy | 18720 (41.24%) |
| Ischemic heart disease | 27541 (60.67%) |
| Prior myocardial infarction | 21497 (47.36%) |
| Prior coronary bypass | 15560 (34.28%) |
| Prior percutaneous coronary intervention | 12818 (28.24%) |
| Previous valvular surgery | 3609 (7.95%) |
| Cerebrovascular disease | 6308 (13.90%) |
| Chronic lung disease | 11254 (24.79%) |
| Diabetes mellitus | 18364 (40.46%) |
| Hypertension | 34344 (75.66%) |
| Renal failure/dialysis | 1693 (3.73%) |
Clinical characteristics related to CRT-D indications and characteristics of medical therapy were also examined ( Table 3 ). Only 71.5% of patients met all 3 clinical criteria (left ventricular ejection fraction ≤35%, QRS duration >120 ms, and New York Heart Association class III or IV symptoms) that represent contemporaneous guideline-based class I indications for CRT. We found 70.3% of those without contraindication were prescribed GDMT consisting of both a β blocker and an ACE-I or ARB at discharge. Additionally, 50.3% met contemporaneous guideline-based class I indications and were prescribed GDMT at discharge, but 8.7% neither met contemporaneous guideline-based class I indications nor received GDMT at discharge ( Table 4 ).
| Description | |
|---|---|
| Cardiac resynchronization therapy with defibrillator clinical criteria for guideline concordance | |
| Left ventricular ejection fraction ≤35% | 44810 (98.72%) |
| QRS duration >120 ms | 37421 (82.44%) |
| New York Heart Association class III or IV | 39433 (86.87%) |
| Class III | 35968 (79.24%) |
| Class IV | 3465 (7.63%) |
| All of above | 32458 (71.51%) |
| Guideline directed medical therapy—among those without contraindications | |
| Beta-blocker | 39190 (87.38%) |
| Angiotension converting enzyme inhibitor | 28029 (64.15%) |
| Angiotension II receptor inhibitor | 8270 (18.56%) |
| Beta-blocker and angiotension converting enzyme inhibitor or angiotension II receptor inhibitor | 31090 (70.26%) |
| All criteria for cardiac resynchronization therapy with defibrillator clinical guideline concordance and receiving guideline directed medical therapy | 22276 (50.34%) |
| On Guideline-Directed Medical Therapy ∗ | Not on Guideline-Directed Medical Therapy ∗ | % on Guideline-Directed Medical Therapy ∗ | |
|---|---|---|---|
| Guideline concordant † | 22276 (50.34%) | 9334 (21.09%) | 70.47% |
| Not guideline concordant † | 8814 (19.92%) | 3826 (8.65%) | 69.73% |
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