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J Am Coll Cardiol, 2006; 47:547-551, doi:10.1016/j.jacc.2005.09.031
(Published online 13 January 2006). © 2006 by the American College of Cardiology Foundation |
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* Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida
Lankenau Hospital, Wynnewood, Pennsylvania
Abbott, Abbott Park, Illinois
University of Munster School of Medicine, Bielefeld, Germany
|| University of Nancy, Vandoeuvre-les-Nancy, France
¶ Department of Medicine, University of Milano-Bicocca, Milano, Italy
# Hospital Clinic, Barcelona, Spain
** Instituto Cardiovascular de Guadalajara, Guadalajara, Mexico

University of Oxford, Oxford, United Kingdom

Prioario Division of Cardiology, Policlinico San Matteo, Pavia, Italy.
Manuscript received May 28, 2004; revised manuscript received September 2, 2005, accepted September 12, 2005.
* Reprint requests and correspondence: Dr. Carl J. Pepine, Division of Cardiovascular Medicine, University of Florida, 1600 SW Archer Road, Gainesville, Florida 32610-0277. (Email: pepincj{at}medicine.ufl.edu).
| Abstract |
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BACKGROUND: Factors leading to adverse outcomes in hypertensive patients with CAD are poorly understood. The INternational VErapamil-trandolapril STudy (INVEST) compared outcomes in hypertensive patients with CAD that were assigned randomly to either a verapamil sustained-release (SR)- or an atenolol-based strategy for blood pressure (BP) control. Trandolapril and hydrochlorothiazide were used as added agents. During follow-up (61,835 patient-years), BP control and the primary outcome (death, nonfatal myocardial infarction, and nonfatal stroke) were not different between strategies.
METHODS: We investigated risk for adverse outcome associated with baseline factors, follow-up BP, and drug treatments using Cox modeling.
RESULTS: Previous heart failure (adjusted hazard ratio [HR] 1.96), as well as diabetes (HR 1.77), increased age (HR 1.63), U.S. residency (HR 1.61), renal impairment (HR 1.50), stroke/transient ischemic attack (HR 1.43), smoking (HR 1.41), myocardial infarction (HR 1.34), peripheral vascular disease (HR 1.27), and revascularization (HR 1.15) predicted increased risk. Follow-up systolic BP <140 mm Hg or diastolic BP <90 mm Hg (HRs 0.82 or 0.70, respectively) and trandolapril with verapamil SR (HRs 0.78 and 0.79) were associated with reduced risk.
CONCLUSIONS: In hypertensive patients with CAD, increased risk for adverse outcomes was associated with conditions related to the severity of CAD and diminished left ventricular function. Lower follow-up BP and addition of trandolapril to verapamil SR each were associated with reduced risk.
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Beta-blocker/diuretic treatment is beneficial, but many trials of these drugs preceded aspirin, statins, MI reperfusion, revascularization, angiotensin-converting enzyme inhibitors, and organ protection; enrolled few patients with CAD; and many had inadequate BP control (2). Calcium antagonists and angiotensin-converting enzyme inhibitors reduce events; however, their value compared with beta-blocker/diuretic treatment has not been sufficiently tested in contemporary hypertensive patients with CAD. The foregoing provided rationale for the INternational VErapamil-trandolapril STudy (INVEST) and for this prespecified analysis to investigate factors leading to risk for adverse outcomes.
| Methods |
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Data analysis.
To identify factors associated with risk for primary outcome, stepwise Cox proportional-hazards regression was used to provide hazard ratios (HRs) and 95% confidence intervals (CIs) for the following baseline covariates: age (10-year increments), gender, race/ethnicity (Caucasian, Asian, black, Hispanic, multiracial/other), U.S. residency, body mass index (BMI) in 5-kg/m2 increments, MI, heart failure (functional class I to III), renal impairment, peripheral vascular disease, aspirin use, left ventricular hypertrophy, smoking (ever), coronary revascularization, stroke/transient ischemic attack, angina pectoris, unstable angina, arrhythmia, hypercholesterolemia, and diabetes. Prespecified covariates (age, gender, race/ethnicity, previous MI, and heart failure), as well as a factor for strategy were forced entries. The remaining covariates were selected by the procedure and retained when p
0.1.
Baseline systolic blood pressure (SBP) and diastolic blood pressure (DBP) were assessed by adding these terms to the aforementioned Cox model. To assess the effect of BP after randomization, we used exploratory Cox regression models excluding treatment strategy both unadjusted and stepwise with BP fit as a time-dependent variable. Here, patients were categorized by SBP <140 mm Hg or
140 mm Hg and DBP <90 mm Hg or
90 mm Hg at each visit. Additionally, a model with terms for baseline covariate, time-dependent SBP category (more than six weeks prior to primary outcome event or censoring) and the interaction term was used to assess the effect of the prognostic factors on primary outcome.
A further model used average daily dose of each strategy drug for each patient and variables indicating the proportion of verapamil SR and trandolapril, or the proportion of atenolol and HCTZ, prescribed simultaneously in addition to treatment strategy; interactions of drug-dose variables with strategy; and prespecified baseline covariates to assess the relationship between study drugs and primary outcome (6). Drug-dose variables were fit as time-dependent. Estimates are presented for selected dose combinations assuming simultaneous proportions are 100%, with atenolol 50 mg/day as the reference (HR = 1.0).
Mean and standard deviation were provided for continuous variables, or number of patients and percent (%) for categorical variables. Statistical significance was assumed if p
0.05 (two-tailed).
| Results |
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At these comparable BPs, exploratory drug-dose modeling using selected doses suggested that added drugs were associated with additional benefits (Fig. 3). Although some combinations of verapamil SR and trandolapril (180 mg/2 mg/day) showed significant risk reduction, all multidrug combinations showed trends for benefit compared with atenolol 50 mg/day alone.
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| Discussion |
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Association between higher BP and increased risk is well established but has not been emphasized for elderly hypertensive patients with CAD. In general, we found in exploratory analyses that time-dependent SBP <140 mm Hg was associated with lower risk, in both the low- and high-risk subgroups defined by baseline conditions (Fig. 2).
When BP is reduced to comparable levels by different drugs, especially in patients with the high-risk conditions identified here, the choice of antihypertensive agents may be important in further reducing risk. Of current interest was the finding that trends to reduce risk appeared for addition of HCTZ to atenolol and trandolapril to verapamil SR. However, adding trandolapril to verapamil SR was associated with significant risk reduction at certain doses, with and without addition of HCTZ. This finding is consistent with results of other trials in high-risk patients (2,9,10). Beneficial trends occurred at all doses of trandolapril, and risk reduction was significant for the 2-mg dose when added to verapamil, despite the fact that trandolapril also was recommended for diabetes, heart failure, or renal impairment in the atenolol strategy. These results should be viewed as support for a multi-drug BP control strategy that includes angiotensin-converting enzyme inhibition in high-risk patients with CAD.
Study limitations.
Patients younger than 50 years of age, those with functional class IV heart failure, with creatinine levels
4.0 mg/dl, or recent stroke, unstable angina, coronary revascularization, or MI were excluded. Surprisingly, increased BMI was not associated with increased risk, but these findings require additional analysis beyond the scope of this publication. Interactions with age, smoking, gender, and disease and, particularly, the increase in all cause mortality observed among those with lower BMI in large adult cohorts (11) make this analysis complex. Yet the possibility remains that when BP is well controlled and organ protection is implemented for heart failure, diabetes, and renal impairment, increased BMI could have less of an impact on outcomes. Because drugs and doses given were dependent on BP response and other factors (e.g., patients well-being), some confounding is unavoidable. Finally, effects of nonstrategy antihypertensive drugs were not analyzed; however, sensitivity analyses indicated they did not alter results qualitatively.
Conclusions. Many conditions in hypertensive patients with CAD impart excess risk. Age, as well as previous diabetes, stroke/transient ischemic attack, smoking, heart failure, renal impairment, MI, peripheral vascular disease, and revascularization are independently associated with increased risk. In general, the high risk associated with these conditions was reduced by achieving a SBP <140 mm Hg. Although both treatment strategies provided excellent BP control, with no difference in outcomes overall, the addition of trandolapril to verapamil SR was associated with reduction in risk, and this combination may offer greater protection than monotherapy. Although all patients with CAD and hypertension require aggressive risk factor modification, the subgroup with these risk conditions may benefit from particularly close surveillance for residual BP elevation and consideration for additional therapies.
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