HRV is a marker of autonomic function and mortality risk. It has been used in our Geriatric Heart Failure Clinic to maximize therapy. Usually, HRV is derived from 24 h Holter monitoring recordings. However, elderly often find it too cumbersome to tolerate. Short-term monitoring would promote compliance. P&S monitoring is directly compared with simultaneously recorded Holter data.

Simultaneous 24 h Holter monitoring and 15.5 min P&S monitoring were obtained from 37 ambulatory, elderly (70–90-year-old, two female) patients at a large geriatric clinic in a veterans hospital. Eight patients were excluded because of high-quality arrhythmia. The 29 patients studied ranged in age from 70 to 90 years old. HRV was computed [6, 7] from each 24 h Holter study, including the initial 15.5 min when P&S monitoring was also being recorded. For each P&S monitor recording, three standard time-domain HRV measures were recorded: rMSSD, pNN50, and SDNN. For a complete methodology describing P&S monitoring, see Fig. 3.​18 and Chap. 5 of this compendium. Time-domain HRV measures from both the 24 hr and the 15.5 min Holter recordings were compared with the P&S monitoring records using the SPSS 11.0 Statistics Program. Correlations were determined using the Spearman rank test. Significance is considered at p <0.05.

Time-domain HRV parameters determined from both 24 h and 15.5 min Holter records and P&S monitoring records revealed comparable results for all but one pairing (see Table 15.1 ). Correlations between the Holter (0.54) and P&S monitoring (0.63) SDNN represent the exception. The Holter was not well correlated (p < 0.068). SDNN values determined from P&S monitoring records were well correlated (p = 0.027). RR intervals, rmsSD, and pNN50 for both the Holter records and the P&S monitoring records were also well correlated.

The data support the fact that Holter and P&S monitoring are comparable. The high levels of correlation suggest that the P&S monitoring methodology provides a useful and well-tolerated tool for quickly obtaining autonomic function analysis in the elderly, particularly in the office setting.

The Autonomic Assessment that accompanies P&S monitoring offers more information when paired with Holter monitoring. P&S monitoring provides P&S responses to challenges that model typical activities experienced daily. The DB challenge simulates patients’ P&S responses to therapy and disease after large meals or before bedtime. The Valsalva challenge simulates patients’ P&S responses to therapy and disease during stress or exercise responses. Resting and PC challenges are self-evident. Therefore, the Autonomic Assessment is like a 15.5 min Holter administered in the office, with the results available immediately.

Youthful sympathetic levels tend to be higher than parasympathetic levels. Healthy geriatric parasympathetic levels are slightly higher than sympathetic levels. The geriatric cardiology literature recommends “more parasympathetic activity” [9], as it is associated with reduced morbidity and mortality [9–11] (see also section “Parasympathetic tone in geriatric patients”). Too much parasympathetic activity is associated with depression, fatigue, exercise intolerance, and other symptoms of PE. Depression, associated with PE, is known to elevate mortality risk in heart disease patients [12]. Given the normal range of SB (0.4< SB <3.0), “more parasympathetic activity” without PE could be defined as low-normal SB (0.4< SB <1.0). Low-normal SB seems particularly important for patients presenting with CAN. It has been documented that CAN is associated with a 50 % greater risk of all-cause mortality than those without CAN [13–15]. In general, CAN is a risk indicator for MI and sudden cardiac death and is associated with greater morbidity and mortality [16, 17]. CAN is defined as the resting parasympathetic measure, RFa, <0.1 bpm². Resting RFa = 0.1 bpm² is the mathematical equivalent to the Framingham Heart Failure Study threshold for high risk of MI or sudden cardiac death [18], with the following caveats:

Resting RFa <0.1 bpm² suggests insufficient parasympathetic power to slow the heart in a sustained tachycardic condition (or worse). If the patient has structural (as opposed to functional) CAN, then evidence suggests that even with low-normal SB, their resting parasympathetic activity will remain below 0.1 bpm². This may be due to denervation of the heart during the insult or surgery. On the other hand, there are patients whose resting parasympathetic activity does return above 0.1 bpm² with low-normal SB. This may be due to the fact that the autonomics are not neuropathic, but rather merely dysfunctional, with the relatively excessive branch suppressing the weaker branch. This indicates functional (as opposed to structural) CAN. Establishing and maintaining proper SB may “release” the suppressed branch (Fig. 15.1) and place it on a par with the formerly excessive branch (see Fig. 3.​18, figure adapted from [1]).

Autonomic profiling of 141 consecutive geriatric patients (24 diabetics, 75 females) was performed using with P&S monitoring. The patients were from three ambulatory clinics in New Jersey, New York, and Pennsylvania, with 81 of them diagnosed with heart failure (age = 75.2 ± 4.9) and 60 non-heart failure patients (age = 82.7 ± 6.5). P&S profiling was based on responses to resting baseline, DB, Valsalva challenge, and PC. See Fig. 3.​18 and Chap. 5 of this compendium for a complete methodology describing the Autonomic Assessment.

As shown in Table 15.2, non-heart failure patients have more activity in both P and S branches, even though their average age is 7.5 years higher that the heart failure patients. On average, the non-heart failure patients have parasympathetic levels greater than their sympathetic levels, suggesting a lower SB. The opposite is true for the heart failure patients. The non-heart failure patients’ average SB is significantly less than the SB for the heart failure patients’. Note the reason for the SB results not equaling the ratio of the average sympathetic to the average parasympathetic result is that the SB is not the ratio of the averages. The SB equals the average of the ratios. This is known to be statistically more accurate.

Even though the non-heart failure patients are significantly older than the heart failure patients, their average resting P&S activity levels are higher, suggesting a “physiologically younger” ANS, and their SB is lower. This may be the reason for their relative longevity.

More parasympathetic activity, as indicated by lower SB, may be associated with improved outcomes and longevity in geriatric patients. Low-normal SB (0.4< SB <1.0) may define the “more parasympathetic activity” recommended by the geriatric cardiology literature.