Long-term Follow-up in Hypertensive Patients With Normal Stress Myocardial Perfusion Imaging: a Parametric Analysis

Objectives We assessed the relationship between arterial hypertension and temporal characteristics of cardiac risk at long-term follow-up in hypertensive patients with a normal stress myocardial perfusion single-photon emission computed tomography (MPS).

Methods We evaluated 471 consecutive hypertensive patients without known coronary artery disease (CAD) and normal perfusion at stress MPS. All patients were followed for a mean 76?21 months. End-point events were cardiac death or nonfatal myocardial infarction. The univariable and multivariable associations with cardiac events were determined by Cox proportional hazards regression analysis. A parametric survival model was used to identify how the variables influenced time to event and to estimate the risk-adjusted event rates during the follow-up.

Results Of the overall population, 299 (63%) patients underwent exercise stress test and 172 (37%) patients pharmacologic stress test with dipyridamole. At Cox analysis, age (hazard ratio 1.1, P<0.005) and stress test type (hazard ratio 2.7, P<0.005) were independent predictors of cardiac events. In patients undergoing exercise stress test, peak systolic arterial pressure (PAS) (hazard ratio 1.1, P<0.005) resulted as predictor of cardiac events. At parametric analysis, patients <60 years old who performed exercise stress test remained at low risk for the entire length of follow-up, while the highest probability of events and the major risk acceleration was observed in patients >60 years old who underwent pharmacologic stress test. In the 299 patients undergoing exercise stress test, only those who reached PAS <160 mmHg remained at low risk for the entire length of follow-up. In contrast, time to achieve a cumulative cardiac risk level of 3% was 49 months in the presence of PAS 160-180 mmHg, 35 months for PAS 180-200 and only 10 months for PAS >200 mmHg.

Conclusions In hypertensive patients without known CAD, a normal stress MPS should be considered reassuring in subjects <60 years old who performed exercise stress test and in those who reached a peak PAS <160 mmHg independently on age. On the other hand, patients who underwent exercise stress test and reached peak PAS >200 and those submitted to pharmacologic stress test should be considered for a more aggressive management.