Intrinsic Frequencies of Carotid Pressure Waveforms Predict Cardiovascular Disease Events: The Framingham Heart Study

Abstract

Introduction and Hypothesis: Intrinsic frequencies (IFs) derived from arterial waveforms, representing the dominant instantaneous frequency during systole and diastole, are associated with cardiovascular performance, aging, and prevalent cardiovascular disease (CVD). However, prognostic value of these novel measures in a community-based sample is unknown. We hypothesized that IFs are associated with risk of incident CVD events. Methods and Results: The sample for this study was drawn from the Original (Exam 26), Offspring (Exam 7), and Third Generation (Exam 1) Cohorts of the Framingham Heart Study and included participants free of CVD at the time of the baseline visit (N=5717; mean age 49 years, 55% women). We used the IF method (a modified version of the sparse time-frequency representation method) to extract the IFs directly from a series of carotid aortic pressure waves using a least squares minimization and a brute-force algorithm to optimize waveform fit. We extracted two dominant frequencies from noninvasive carotid pressure waveforms: the IF of the coupled heart and vascular system during systole (ω₁) and the IF of the decoupled vasculature during diastole (ω₂). Total frequency variation (Δω) is defined as the difference between ω₁ and ω₂. We used Cox proportional hazards regression models to relate individual IF measures to a first incident CVD event during a mean follow-up of 10.7 years (Table). In multivariable models adjusted for cardiovascular risk factors plus heart rate and ventricular ejection period, higher ω₁ and Δω but lower ω₂ were associated higher risk for incident composite CVD and heart failure events. In contrast, IFs were not significantly associated with incident myocardial infarction or stroke. Conclusion: These novel IFs may represent valuable markers of HF risk in the community.

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