Association of Guideline-Based Admission Treatments and Life Expectancy After Myocardial Infarction in Elderly Medicare Beneficiaries

Abstract

Background: Guideline-based admission therapies for acute myocardial infarction (AMI) significantly improve 30-day survival, but little is known about their association with long-term outcomes.

Objectives: This study evaluated the association of 5 AMI admission therapies (aspirin, beta-blockers, acute reperfusion therapy, door-to-balloon [D2B] time ≤90 min, and time to fibrinolysis ≤30 min) with life expectancy and years of life saved after AMI.

Methods: We analyzed data from the Cooperative Cardiovascular Project, a study of Medicare beneficiaries hospitalized for AMI, with 17 years of follow-up. Life expectancy and years of life saved after AMI were calculated using Cox proportional hazards regression with extrapolation using exponential models.

Results: Survival for recipients and non-recipients of the 5 guideline-based therapies diverged early after admission and continued to diverge during 17-year follow-up. Receipt of aspirin, beta-blockers, and acute reperfusion therapy on admission was associated with longer life expectancy of 0.78 (standard error [SE]: 0.05), 0.55 (SE: 0.06), and 1.03 (SE: 0.12) years, respectively. Patients receiving primary percutaneous coronary intervention (PCI) within 90 min lived 1.08 (SE: 0.49) years longer than patients with D2B times >90 min, and door-to-needle (D2N) times ≤30 min were associated with 0.55 (SE: 0.12) more years of life. A dose-response relationship was observed between longer D2B and D2N times and shorter life expectancy after AMI.

Conclusions: Guideline-based therapy for AMI admission is associated with both early and late survival benefits, and results in meaningful gains in life expectancy and large numbers of years of life saved in elderly patients.

Keywords: acute myocardial infarction; elderly; guidelines; life expectancy; survival.

Central Illustration. Acute MI Admission Therapies and Life Expectancy: Average Number of Life-years Saved

Prior studies have invariably evaluated improvements in short-term outcomes due to AMI guideline-based therapies. In this study, we quantified life expectancy after AMI and the number of life-years saved by these therapies. Cox proportional hazards regression with extrapolation using exponential models were used to calculate the number of life-years saved attributable to these therapies. All 5 therapies were associated with substantial numbers of life-years saved on average in elderly AMI patients, illustrating the importance of early and rapid delivery of these therapies.

Figure 1. Flow diagram of study inclusion criteria

Separate eligibility criteria were used for each guideline. “Ideal candidates” were defined as being eligible for a particular therapy without specific contraindications per American Heart Association/American College of Cardiology guidelines.

Figure 2. Expected survival curves for those receiving and not receiving A) Aspirin within 48 hours, B) Beta-blockers within 48 hours, C) Acute reperfusion therapy within 12 hours, D) Door to balloon within 90 minutes, and E) Door to needle therapy within 30 minutes, among those eligible for these therapies

Unadjusted survival curves were calculated using Cox proportional hazards models with only therapy receipt included in the model statement. Survival curves of therapy recipients (red line) and non-recipients (blue line) separated early after admission and remained distinct over the entire duration of follow-up. In all cases, therapy recipients had significantly higher survival than non-recipients.

Figure 2. Expected survival curves for those receiving and not receiving A) Aspirin within 48 hours, B) Beta-blockers within 48 hours, C) Acute reperfusion therapy within 12 hours, D) Door to balloon within 90 minutes, and E) Door to needle therapy within 30 minutes, among those eligible for these therapies

Unadjusted survival curves were calculated using Cox proportional hazards models with only therapy receipt included in the model statement. Survival curves of therapy recipients (red line) and non-recipients (blue line) separated early after admission and remained distinct over the entire duration of follow-up. In all cases, therapy recipients had significantly higher survival than non-recipients.

Figure 2. Expected survival curves for those receiving and not receiving A) Aspirin within 48 hours, B) Beta-blockers within 48 hours, C) Acute reperfusion therapy within 12 hours, D) Door to balloon within 90 minutes, and E) Door to needle therapy within 30 minutes, among those eligible for these therapies

Unadjusted survival curves were calculated using Cox proportional hazards models with only therapy receipt included in the model statement. Survival curves of therapy recipients (red line) and non-recipients (blue line) separated early after admission and remained distinct over the entire duration of follow-up. In all cases, therapy recipients had significantly higher survival than non-recipients.

Figure 2. Expected survival curves for those receiving and not receiving A) Aspirin within 48 hours, B) Beta-blockers within 48 hours, C) Acute reperfusion therapy within 12 hours, D) Door to balloon within 90 minutes, and E) Door to needle therapy within 30 minutes, among those eligible for these therapies

Unadjusted survival curves were calculated using Cox proportional hazards models with only therapy receipt included in the model statement. Survival curves of therapy recipients (red line) and non-recipients (blue line) separated early after admission and remained distinct over the entire duration of follow-up. In all cases, therapy recipients had significantly higher survival than non-recipients.

Figure 2. Expected survival curves for those receiving and not receiving A) Aspirin within 48 hours, B) Beta-blockers within 48 hours, C) Acute reperfusion therapy within 12 hours, D) Door to balloon within 90 minutes, and E) Door to needle therapy within 30 minutes, among those eligible for these therapies

Unadjusted survival curves were calculated using Cox proportional hazards models with only therapy receipt included in the model statement. Survival curves of therapy recipients (red line) and non-recipients (blue line) separated early after admission and remained distinct over the entire duration of follow-up. In all cases, therapy recipients had significantly higher survival than non-recipients.

Figure 3. Age-specific absolute and relative numbers of life-years saved from (A) aspirin, (B) beta-blockers, and (C) acute reperfusion therapy after myocardial infarction

Numbers of life-years saved were calculated using marginal Cox proportional hazards models with extrapolation using exponential models. Analyses have been adjusted for patient demographics (gender, age, race, ZIP-code level median household income percentile), medical history (hypertension, diabetes, previous coronary artery disease, chronic heart failure, cerebrovascular accident, chronic obstructive pulmonary disease, chronic kidney disease, current smoking, obesity, cancer, dementia, anemia), frailty measures (admission from a skilled nursing facility, mobility and urinary continence on admission), clinical presentation (Killip class > 2, anterior AMI, pulse and systolic blood pressure on admission, STEMI, cardiac arrest), receipt of other therapies (aspirin, beta-blockers, and acute reperfusion therapy), and hospital characteristics (AMI volume per year, rural location, hospital ownership, and teaching status).

Figure 4. Years of life lost associated with increasing (A) door-to-balloon and (B) door-to-needle time

Years of life lost by patients with longer door-to-balloon and door-to-needle times are calculated in reference to patients with door-to-balloon times ≤ 90 minutes and door-to-needle times ≤ 30 minutes, respectively. Analyses have been adjusted for patient demographics (gender, age, race, ZIP-code level median household income percentile), medical history (hypertension, diabetes, previous coronary artery disease, chronic heart failure, cerebrovascular accident, chronic obstructive pulmonary disease, chronic kidney disease, current smoking, obesity, cancer, dementia, anemia), frailty measures (admission from a skilled nursing facility, mobility and urinary continence on admission), clinical presentation (Killip class > 2, anterior AMI, pulse and systolic blood pressure on admission, STEMI, cardiac arrest), receipt of other therapies (aspirin, beta-blockers, and acute reperfusion therapy), and hospital characteristics (AMI volume per year, rural location, hospital ownership, and teaching status).