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Chronotropic incompetence, measured by the % heart rate (HR) reserve achieved (%HR-reserve), abnormal HR-recovery, and reduced exercise capacity (EC) are known predictors of all-cause mortality (ACM). We examined whether these variables add incremental value for predicting ACM in pts undergoing exercise myocardial perfusion SPECT (MPS).
12,291 pts not on β blockers underwent exercise MPS. Poor EC was defined as ≤ 7 METS. %HR-reserve was defined as (peak HR – rest HR) × 100/(220-age-rest HR) with <80% being low. HR-recovery was defined as peak HR – recovery HR at 2 min with < 22 considered abnormal. Cox regression analysis was performed.
There were 519 deaths (follow-up = 1182 + 827 days). 2,716 (22.1%) had abnormal HR-recovery, 3,579 (29.2%) had low %HR-reserve, and 4,801(39.1%) had poor EC. In a multivariate model of ACM, the independent predictors were age, χ2= 71.7; EC, χ2=53.6; MPS extent/severity, χ2=31.4; symptom, χ2=24.1; %HR-reserve, χ2= 23.6; transient ischemic dilation, χ2=17.7; HR-recovery, χ2=12.7; abnormal rest ECG, χ2=11.8; diabetes, χ2=10.2. The figureshows the observed relationship between EC, %HR-reserve, HR-recovery, and ACM. At 3 yrs, pts with normal %HR reserve, HR-recovery, and EC had a 1.5% risk of ACM. With 1, 2, or 3 abnormalities, the ACM progressively increased (3.7%, 7.8%, and 15.2%, respectively).
Exercise capacity, %HR-reserve, and HR-recovery are independent and incremental predictors of ACM in pts undergoing exercise MPS.
Poster Sessions, Expo North
Monday, March 11, 2013, 9:45 a.m.-10:30 a.m.
Session Title: Prognostic Implications in Nuclear Imaging
Abstract Category: 21. Imaging: Nuclear
Presentation Number: 1315-359
- 2013 American College of Cardiology Foundation