Sandeep Krishnan

Prevalence of Resistant Hypertension and Eligibility for Catheter-Based Renal Denervation in Hypertensive Outpatients

BACKGROUND Studies of endovascular renal denervation (RDN) have demonstrated significant blood pressure reduction in eligible patients with resistant hypertension. These trials have used stringent inclusion and exclusion criteria in patient enrollment, potentially selecting for a small subset of patients with resistant hypertension. In this study, we examined the changes in estimated prevalence of resistant hypertension when using increasingly stringent definitions of resistant hypertension in a fixed population and assessed the generalizability of RDN when applying study criteria to a community-based hypertensive population. METHODS A retrospective chart review was done of hypertensive outpatients. Four increasingly stringent interpretations of the American Heart Association definition of resistant hypertension were used to calculate prevalence estimates. Patients eligible for RDN were identified using criteria from SYMPLICITY HTN-3. Demographic and clinical characteristics were compared. RESULTS We identified 1,756 hypertensive outpatients; 55.0% were male, 53.9% were white, and subjects had a mean age of 66.6 ± 12.5 years and a body mass index (BMI) of 30.1 ± 10.7 kg/m(2). Only 14 (0.8%) were eligible for RDN. Among these patients, 10 (71.4%) were female and all were black, with a mean age of 69.9 ± 8.8 and BMI of 35.7 ± 6.6. Congestive heart failure was more common in patients eligible for RDN. CONCLUSIONS Patients eligible for RDN based on published studies represent an exceedingly small proportion of the total hypertensive population. Further studies are necessary to determine if the benefits of RDN can be generalized to a broader range of hypertensive patients than those included in previous trials.

Looking for the bare necessities

The authors suggest that the early durability of the CoreValve implant should not be in question based on the results of this modestly sized, but well‐done postmortem observational study. Given the ever‐expanding knowledge of valvular degeneration, one thing is clear: more research and study is needed before any routine change in clinical practice, such as change it antithrombotic therapy, can be recommended. Further autopsy studies of patients who die outside of typical healthcare settings and who have had a longer median implant time would aid greatly in furthering the understanding of the degeneration and natural history of bioprosthetic transcatheter heart valves.

Novel bipolar preshaped left ventricular pacing wire for transcatheter aortic valve replacement

Right ventricular (RV) rapid pacing with a dedicated temporary pacing wire remains a stalwart technique to help stabilize cardiac position during transcatheter aortic valve replacement (TAVR), particularly with balloon expandable devices. Although rapid pacing is required for balloon expandable TAVR, the use of RV pacing has been associated with a small but recognized rate of serious morbidity [1–3]. It also necessitates an additional venous access point, which adds time and expense to the procedure. In an effort to streamline TAVR procedures and avoid attendant complications, there has been a growing interest in utilizing the required 0.03500 left ventricular (LV) delivery wire as a pacemaker [4]. Though this concept is appealing in practice, the use of existing guidewires for pacing may be challenging since such wires are not insulated against current loss in the blood pool and therefore: (1) cannot be tested for ventricular capture unless they are insulated within the body with a valvuloplasy balloon or a TAVR device; (2) cannot provide obligate pacing following TAVR without the delivery system left in place; (3) can only provide unipolar pacing in conjunction with a grounding needle in the subcutaneous tissue and a non-dedicated connection to an electrical source; and (4) generally have higher pacing capture thresholds and less safety margin due to unipolar pacing [4]. Thus, a purpose built TAVR delivery wire with intrinsic pacing system with insulated bipoles capable of consistent LV pacing at low thresholds with or without a delivery system in place may improve procedural safety and efficiency without compromising traditional pacing characteristics. We tested such a concept utilizing a series of novel Bipolar Temporary Pacing Guidewires (Vascular Solutions, Minneapolis, MN) in a swine model. These 0.035” pre-shaped wires positioned positive and negative nodes in different configurations along the distal aspect of the wire. The wire has a dedicated connector that interlocks the positive and negative outputs from a standard pacing cable to the TAVR delivery wire’s electrical contacts distally. The TAVR delivery pacing wires were tested for capture threshold in two different locations—the apex and mid-left ventricle—and with positive and negative polarities reversed sequentially. Rapid pacing ability and functionality during inflation of a 20 mm Edwards’ Sapien 3 valve delivery system (Edwards LifeSciences, Irvine, CA) was also tested. The primary objective was to demonstrate consistently acceptable rapid pacing capture thresholds and persistent pacing induced hypotension under a series of unique conditions and positions. Three separate wires were tested in a porcine model. Capture thresholds were evaluated with the wire positioned in the LV apex and mid-cavity at a rate of 130 beats per minute (bpm) using both positive and negative polarity at the distal node. Rapid pacing ability was confirmed at 180 bpm with balloon inflation. Additionally, the pacing wires were tested with the Sapien 3 delivery sheath in different positions in relation to the electrodes on the LV pacing wire. Pacing of the porcine heart was conducted with zero, one, and two of the electrodes covered. Thresholds were tested in each of these conditions and data was recorded (Table 1). As a control, unipolar LV pacing was tested in a second porcine model using an Amplatz Super Stiff (Boston Scientific, Boston, MA) and a subcutaneous ground using a 22 gauge needle in the subcutaneous tissue as previously described [4]. The wire was insulated with a 5 French AR1 diagnostic catheter. We then repeated capture threshold testing in the mid-cavity and apical LV positions and rapid pacing at 180 bpm. Among the novel bipolar wires, capture thresholds were 1.26 0.36 mA when the wire was positioned at the apex, and 1.7560.25 mA when positioned in the LV mid-cavity, out of contact with the apex. There was no meaningful difference in capture threshold based on polarity of the distal pole. Rapid pacing at 180 bpm was then successfully achieved with all wires at 23 capture threshold. We subsequently introduced an S3 delivery system and re-confirmed consistent rapid pacing ability at 23 capture threshold during delivery system inflation (Figure 1). The system appeared to be stable and capture was not lost during minor manipulations of the valve during deployment. In the control arm, capture thresholds were 6.0 and 5.0 mA with the Super Stiff wire in the mid-cavity and LV apical positions respectively. Rapid pacing at 180 bpm was also confirmed at 23 capture threshold in both positions. We report for the first time the use of a novel purpose-built 0.03500 bipolar pacing delivery guidewire (Vascular Solutions, Minneapolis, MN) designed to potentially improve the safety and efficiency profile of TAVR. Our data in a porcine model suggests capture thresholds on par with traditional temporary RV pacing wires and significantly lower than those seen with standard guidewires acting as a unipolar system in the left ventricle. Unlike standard guidewires, this wire does not require insulation in the form of an over-the-wire device to function, and therefore threshold testing can be carried out immediately after placement. Furthermore, the mechanical properties of this novel wire, including its preshaped tip (Figure 2), demonstrated no preliminary safety concerns during delivery of a balloon-expandable valve delivery system from the femoral artery to native aortic valve.

Dollars and stents: A brave new world

Reimbursement in the healthcare system is shifting from pure volume to a mixed volume/value‐based metric. Using complex statistical modeling to adjust for unknowns, the study provides real world data that the use of Co‐Cr EES is more cost effective than BMS assuming that clinicians select clopidogrel for P2Y12 inhibition. More cost‐effectiveness analyses should be conducted to guide the use of ever costlier novel medical devices and drugs.

The invisible scaffold…with invisible benefits?

Authors suggest the use of an investigator‐owned and directed, prospective, non‐randomized, single‐arm multicenter registry at 23 Italian hospitals to follow 500 STEMI patients who receive BVS. Follow‐up of patients is out to 5 years to determine how a BVS which has been deployed according to the IFU performs in these ACS patients. There is no comparator arm. Mandate that patients included in this registry follow a strict BVS implantation protocol which is felt to mitigate the not insignificant stent thrombosis rates noted with BVS to date.

The bare naked truth… “excuse me but your metal is showing!”: Krishnan and Henry

In 11,181 consecutive STEMI patients, the use of DES increased over time and there were significant differences in patients who received DES versus BMS Using complex statistical modeling to adjust for measured and unmeasured confounders, the study provides real world data that the use of DES in STEMI is associated with reduced TVR and improved long‐term survival Overwhelming evidence supports the use of current‐generation DES as first line for STEMI

Statins in patients with CKD prove beneficial in reducing cardiovascular events and mortality but show no benefit in patients on dialysis

Commentary on: Palmer SC, Craig JC, Navaneethan SD, et al. Benefits and harms of statin therapy for persons with chronic kidney disease: a systematic review and meta-analysis. Ann Intern Med 2012;157:263–75. High-quality evidence suggests that chronic kidney disease (CKD) should now be considered a coronary heart disease (CHD) risk equivalent. Although statin therapy consistently reduces coronary events in the general population, the clinical benefits of lipid lowering in persons with CKD are less certain. Although multiple studies have shown possible benefit from statin therapy in early-stage CKD patients, there has been a recent concern that patients with more severe CKD, such as those on dialysis, do not seem to benefit. The authors identified randomised controlled trials with statins from a previously published meta-analysis,1 and supplemented it with recent trials identified in EMBASE, the Cochrane Central Register of Controlled Trials and the Cochrane Renal Groups Specialised …